The Practical Management of Cancer Pain

(A free article from Wanterfall eBooks, written by Dr Gordon Coates)

You can read other articles HERE, read books online HERE, or download PDF files HERE

 

Explanatory Note:

This page contains an annotated version of an article published in the Medical Journal of Australia in 1985, which may possibly be of historical interest to health care professionals. For a comprehensive, non-technical guide to the current management of cancer pain, see my series of articles about cancer pain written in 2011 (also available as a free ebook, entitled How Cancer Pain is Treated).


Notes regarding reproduced content:

1. My earlier review of cancer pain management is reproduced here by permission of the copyright owner, Australasian Medical Publishing Company (AMPCo). I have added a number of  annotations, as explained below.

(The original article, in PDF format, is available HERE)

2. AMPCo requires that any extracts of the content of the original article must include the following reference: Dr Gordon Coates. Management of cancer pain. A practical approach. MJA 1985; 142: 30-35.

3. Reproduction of the whole of the original article would require written permission from AMPCo, who may be contacted by email at ampco@ampco.com.au or by mail at Locked Bag 3030, Strawberry Hills, NSW 2012.

4. I have made a number of annotations (which are not part of the original article) in order to highlight changes in "best practice" between 1985 and 2010. The annotations are identified by bold type (which is also blue, in the html version) and are enclosed within square brackets. Each annotation begins with "AA:" (which stands for "Author's Annotation"). Therefore, the annotations look like this: [AA: However, recent randomised controlled trials suggest...] (but of course they may not be coloured blue in non-html versions).

5. Because the annotations are not part of the original article, they are not subject to the copyright held by AMPCo. Instead, like all my recent publications, they may be freely reproduced under their Creative Commons Attribution-Noncommercial-Share Alike 2.5 Australia License.)

6. As I withdrew from clinical practice in 2007, in order to write books and articles based on my forty years of experience as a physician; and as my clinical practice was only limited to tertiary referral Palliative Medicine for about a decade during the 1980s and 1990s; the annotations should be taken as a guide only, and should be confirmed by a practising Palliative Care or Pain Management specialist before accepting them as accurate. It should also be remembered that the original article, though well received in 1985, is now "very long in the tooth".

7. Although I have made every effort to avoid errors, it must not be assumed that I have succeeded! In any case, with or without errors, both the original article and the annotations are provided for educational purposes only. None of the content is intended as direct medical advice about the management of any patient, nor should it be interpreted in that way.

Management of cancer pain:
A practical approach

Source: Dr Gordon Coates. Management of cancer pain. A practical approach. MJA 1985; 142: 30-35. ©Copyright 1985. The Medical Journal of Australia - reproduced with permission

ABSTRACT

One in five deaths in Australia is due to cancer. Pain is an important symptom in many of these patients, but it is often either unrelieved or poorly controlled. Misconceptions about the nature of cancer pain and its control are detailed, and the practical management of these patients is discussed in the light of personal experience. Proper use of older therapeutic methods is still important, as recent advances allow better results only in a minority of cases. Special attention is given to the use of regular oral doses of morphine. Many of the interacting factors affecting pain perception are considered, so that the sense of impotence in those faced with the management of a progressive incurable disease may be reduced through an understanding of the causes of pain and its correct management.

(Med J Aust 1985; 142: 30-35)

 

IN AUSTRALIA, as in other Western countries, about one in every five persons dies from cancer.1 Of these, many suffer pain which is often prolonged and severe.2 Yet, it has been shown by overseas workers that adequate treatment can prevent or relieve cancer pain in the great majority of cases, and that such treatment need be neither unduly complex nor prohibitively expensive.3,4 My own experience has confirmed these reports and, in this paper, I consider possible reasons for poor pain control and give a brief account of those therapeutic methods which I have found to be most useful.

Misconceptions about cancer pain

The impression that pain is both inevitable and intractable is common among patients and those caring for them, including doctors and nurses. This arises from a variety of causes, such as inadequate professional education, ingrained and widespread fears and taboos, and lack of specific experience in cancer pain management. The result is often a sense of impotence leading to therapeutic nihilism, and many of my patients have previously been told: "Of course you've got pain - you've got cancer". On the other hand, some professionals deny the problem, and this is reinforced by the fact that their patients soon realize the futility of complaining about pain.

A major problem arises from the mistaken beliefs that the long-term use of strong opioids in cancer pain management is precluded by the development of tolerance and the risk of addiction, and that the standard doses of opioids used in the treatment of acute pain are applicable to that of chronic cancer pain. As will be discussed later, the facts are otherwise.5

In the terminal phase of their illness, patients with cancer are sometimes transferred to small, non-acute hospitals and nursing homes the staffing levels of which are inadequate for good palliative care.6 Here they may be "out of sight, out of mind" (but not out of pain!) - the referring clinician having abdicated his own responsibility for their well-being.

Another common error is to rely upon a single method of pain control rather than a combination of techniques. Also, non-specific factors which affect pain perception must not be neglected, as attention to their resolution or alteration may complement the treatment regimen and result in successful pain control.

Clinical approach

Prophylaxis is obviously the best treatment when it is feasible. In some cases, it is possible to prevent manifestations or complications of cancer which might give rise to pain. One example is excision of an incurable rectal cancer to prevent the later onset of spasm and discharge. Less dramatic, but also important, are the care of pressure points, and the prevention of constipation.

All patients with cancer must be assessed for the presence or absence of pain, which is not always obvious. A patient with an extroverted personality may make frequent complaints about pain and requests for relief. Introverts, especially in the terminal phase of their illness, often make neither; non-verbal communication then becomes critical to the establishment of rapport, and a good rule of thumb is "if you don't sit down, you won't find out".

In an endeavour to understand the pain, diagnose its cause and provide the appropriate treatment, a pain history, such as that incorporated by Melzack in the McGill Pain Questionnaire,7 should be taken. The checklist should include the site of pain (and its radiation, if any), its type and severity, sleep disturbance, mode of onset, date and place of first attack, frequency and duration of attacks, and anything which precipitates, is associated with, or relieves, the pain.

[AA: In other words,

Site, Shooting, Sort, Severity, Sleep disturbance and mode of onSet

Precipitating, Associated and Relieving factors

Time factors...

(such as when first experienced, whether related to time of day or time of other events, whether constant, regularly intermittent or randomly intermittent; if constant, whether variable in intensity; and if intermittent or of variable intensity, whether present and how severe now, how often experienced, duration of episodes, duration of partial or complete remissions and duration of the waxing and waning phases)

Incidentally, if you like mnemonics, 6 Shots PAR from the Tee works for me.]

The examination will then be guided by the history, and any investigations will be chosen on the basis of both. Two important compromises apply here. First, the steps towards diagnosis must be appropriate to the patient's condition: a history may be limited or absent, weakness or pain on movement may restrict examination, and investigations which are tiresome, painful, or require an ambulance ride may cause more distress than is justified. Second, there is rarely any need for all palliation to be withheld pending an accurate diagnosis - in fact, there are occasions when the patient should be receiving a slow intravenous injection of morphine while the doctor gathers information about symptoms and signs. Agony is an emergency.

When a specific diagnosis cannot be made, it is still important to determine the general type of pain: for instance, bone pain from secondary tumours (often described as a severe, nagging, dull ache, and tender on percussion), nerve irritation (sometimes called "toothachey" or "like bad pins and needles", often with sharp shooting episodes precipitated by movement), colic from hollow muscular viscera (with its characteristic periodic nature), and raised intracranial pressure (with headache and, sometimes, vomiting and papilloedema) all respond to different treatments. A useful pointer here is that pain originating from connective tissues can usually be fairly easily described and localized in a way that makes anatomical sense, whereas pain from visceral parenchyma is often vaguely described, poorly localized, and is associated with autonomic effects such as nausea, sweating, and tachycardia.

Palliation

Not all pain in patients with incurable cancer is due to cancer, so non-malignant causes of pain should not be overlooked. More often, however, palliation is the best that can be achieved.

Palliation involves the therapy of tumour deposits and their local effects, interruption of the pain pathway, immobilization of the painful parts, and elevation of the pain threshold.8 The last of these is often neglected or poorly carried out, and will therefore be described in more detail than the other three.

Therapy of tumour deposits and their local effects

The aim here is to reduce the bulk of tumour deposits to prevent their local effects, and to remove or bypass any obstruction they may be causing in a hollow organ. Tumour bulk can be reduced by surgery, radiotherapy, cytotoxic chemotherapy, hormone therapy, cryotherapy or immunotherapy. The choice of method used should be made in consultation with the appropriate specialist.

Pain from the local effects of bony secondary tumours usually responds to radiotherapy.9 Fungating lesions are much more comfortable if they are kept clean, and various topical applications may also be useful. When a tumour compresses or infiltrates a nerve, radiotherapy may again be effective,8 as can the administration of corticosteroid agents, but continuous analgesia or interruption of the pain pathway is usually also necessary.

The severe headache of cerebral oedema associated with primary or secondary brain tumours, often responds to treatment with dexamethasone ([AA: often at a dosage of] 4 mg four times a day); occasionally, the dose must be increased, even up to 12 mg each time [AA: on rare occasions]. After control of pain is achieved, the dose may be reduced cautiously towards 2 mg twice a day if the life expectancy is more than a few months.10 Even the latter dose is the equivalent of 40 mg of prednisolone a day, so cushingoid effects are not long delayed. The use of diuretic agents and head elevation also reduce intracranial pressure. One should bear in mind that morphine may raise intracranial pressure, but its use may be necessary for pain relief if the other measures, plus the administration of non-narcotic analgesic agents, prove ineffective.

Bowel obstructions may need relieving by open operation; other obstructions are often relieved by the endoscopic or percutaneous passage of various tubes. Multiple or recurrent bowel obstruction, however, is often better treated medically in a terminally ill patient.11 This is a common problem in patients with carcinoma of the ovary and carcinoma of the bowel. It is usually best managed with nothing by mouth (or ice to suck, sparingly); the administration of opioid analgesic and antispasmodic agents to prevent colic; and (if symptoms of dehydration are present) the intravenous, subcutaneous or rectal administration of fluids. Oral medication is generally contraindicated in these circumstances, but an orally administered combination of diphenoxylate and atropine (Lomotil) has proved to be very effective;11 the rectal administration of oxycodone (Proladone suppositories) is also suitable.

Interruption of the pain pathway

Nerve interruption can be carried out at any point between the site of origin of the pain and the cerebral cortex.12 This option should always be considered, as it is occasionally the best treatment, even if it is carried out near the end of the patient's life. The decision on such action is best made in the setting of a multidisciplinary pain clinic, or in consultation with an anaesthetist and a neurosurgeon, when simpler methods fail. Available procedures include peripheral nerve blocks, plexus blocks, posterior root division, intrathecal or epidural blocks, selective anterolateral cordotomy, and commissural myelotomy. Cordotomy, in particular, can give almost miraculous relief of unilateral pain below the level of the neck or of unilateral or bilateral pain below the mid-thoracic level;12 myelotomy can be similarly effective for pelvic pain or pain in the lower limbs. [AA: However, recent developments such as spinal cord stimulation and neuromodulation of the cingulum have largely superseded some of the earlier neurosurgical pain control techniques.]

Discussion of indications for, and details of, these procedures is beyond the scope of this article. The essential point is that failure of simpler methods is an indication for referral, not despair.

Immobilization

Sometimes, for example, after a pathological fracture, analgesia without immobilization would virtually necessitate general anaesthesia. Thus, a pathological fracture should usually be treated by internal fixation, preferably on the day of fracture, as the patient's fitness for operation may deteriorate rapidly. Even if strong fixation is impossible, because of the extent of bone destruction, it should be possible to render the fracture relatively pain-free with the use of acrylic cement.13

When there are multiple pathological fractures, complete bed rest and as near total body immobilization as is consistent with the patient's needs (pressure point care, elimination, etc) is occasionally necessary.

The value of immobilization, sometimes combined with elevation of a limb, is not restricted to fractures. It may, at times, be appropriate for almost any painful lesion.

Elevation of the pain threshold

Medication

The use of analgesic and co-analgesic agents is the most obvious way of raising the pain threshold, and perhaps the most important as well. However, it is a mistake to rely on them entirely. Also, it is absolutely essential to distinguish clearly between acute pain and chronic pain. Acute pain is of short duration, is usually caused by a self-limiting (or fatal) condition, is associated with anxiety, and typically responds to a single injection of a short-acting opioid drug. Chronic pain is endless, is apparently meaningless, is often accompanied by depression, and never responds to "prn" medication. It is the type of pain usually encountered in the management of patients with cancer.

In general terms, there are four rules for the prescribing of analgesic agents: choose the right drug(s) for the type of pain involved; order the right dosage regimen; take precautions to prevent side-effects; and, most important of all, reassess the requirements frequently.

Choice of drugs

There are three main groups of drugs: non-narcotic analgesic agents, such as aspirin and indomethacin; opioid agents, such as codeine and morphine; and co-analgesic (or adjuvant) agents which enhance the effect of analgesic drugs. It is quite often necessary to prescribe one or (occasionally) more agents from each group for the one patient.

Non-narcotic analgesic agents - such as the non-steroidal anti-inflammatory agents - work by interfering with prostaglandin synthesis,14 and, with the exception of paracetamol [AA: acetaminophen], they are effective at the site of origin of the pain as well as having a central effect. They are specifically indicated for pain of connective tissue (especially bone and visceral capsule) origin. If necessary, an opioid agent should be added rather than substituted.15

Opioid agents work by interference with the transmission and perception of pain in the central nervous system.14 They are specifically indicated for pain of visceral origin (including skeletal muscle), but they may need to be added to other agents in the treatment of severe pain of any origin. A weak opioid agent, such as codeine, or one of medium strength, such as oxycodone, may be sufficient to control pain. (Pentazocine should be avoided; its analgesic effect is weak,16 but it has serious side-effects,17 and can precipitate opioid withdrawal symptoms.18)

The choice of a strong opioid agent remains controversial. Twycross has made an excellent case for morphine,5 and my own experience leads me to consider this the drug of choice in terminal care. Methadone has the advantages of less variable absorption and a longer duration of action than morphine, usually allowing a twice or three times a day regimen. However, its effective half-life may lengthen unpredictably after dosage stabilization, possibly due to transition from distributive to metabolic clearance from the blood, resulting in delayed cumulative toxicity if regular doses are continued.19 For this reason, I have reservations about its use in terminal care, in which the diagnosis of delayed toxicity is very easily missed. Buprenorphine has been the subject of some encouraging reports, and it may yet prove to be a useful addition. Pethidine is rarely useful in the management of chronic pain because its action is weak when given by mouth and short-lived when administered by injection,20 and its maximum dosage is severely restricted by its central nervous system side-effects.14 Dextromoramide should never be used in the treatment of chronic pain which it could probably control smoothly only if taken every 90 minutes around the clock, that is, 16 times a day;5 it is, however, useful for "breakthrough pain". Heroin is not available in Australia, but research by Twycross5 and others suggests that its only major advantage over morphine, when each is used optimally, is its greater solubility in water. Recent research into opioid receptors and endogenous opioids raises the possibility of future breakthroughs in opioid analgesic agents, but has so far contributed only an improved understanding of their mechanisms of action.

Co-analgesic drugs are a loosely defined group, which may help when analgesic agents alone are unsuccessful. They include major and minor tranquillizers, antidepressant, corticosteroid and antispasmodic agents, to which some would add the antiemetics and laxatives used to prevent the side-effects of opioid analgesic agents. Chlorpromazine has been widely used [AA: though much less commonly nowadays] to potentiate the analgesic action of strong opioid agents.5 It also has antiemetic and anxiolytic effects. However, it is often poorly tolerated by weak or elderly patients, causing confusion and a peculiarly "dead" mental state which is distressing for the patient, relatives and staff. Alternatives include diazepam and haloperidol which have their own, rather different, drawbacks. Tricyclic anti-depressant agents have proved valuable in the treatment of the depression which so often accompanies chronic pain, and of the iatrogenic depression which frequently occurs after a few months' regular treatment with opioid analgesic agents. [AA: Small doses of tricyclic anti-depressants also have a valuable role in the management of some types of neurogenic pain.] An antispasmodic agent, such as hyoscine butylbromide, is an obvious co-analgesic drug in the case of colicky pain. Interestingly, indomethacin has been shown to be effective in some types of colic.21 I have used it successfully in suppository form, in the treatment of rectal spasm.

As mentioned above, it is often necessary to use combinations of drugs, as well as other modalities, to achieve analgesia. A good example is provided by inoperable carcinoma of the pancreas, in which pain may originate from the parenchyma, from spasm of the ducts, from stretching of the capsule, and from inflammation and infiltration of adjacent structures, and it may need coeliac plexus block, radiotherapy, and combined drug therapy to achieve analgesia. Nerve-root infiltration by a tumour is the cause of another type of pain which often seems to require combined therapy.

Dosage regimen

Dosages of the weaker opioid and the non-narcotic analgesic agents are, usually limited by side-effects or by the number of tablets required (taking more than three tablets at a time is distressing to many patients). Morphine, however, has no "maximum dose". It can be used in doses much higher than those recommended for the control of acute pain, and neither tolerance nor addiction are real problems when it is used properly in the management of cancer pain.22,23 The oral dose of morphine required for chronic cancer pain in adults may lie anywhere between 1 mg [AA: one milligram] every six hours (for some cachectic patients) and 1000 mg [AA: one thousand milligram, i.e. one gram] every two hours (for occasional patients with severe pain, poor absorption and considerable tolerance). In practice, doses are best adjusted as necessary within a range prescribed by the doctor. These adjustments should be made by someone who is on the spot which, in hospitals, usually means the nursing staff members. A clear chart should be used to keep track of the dosage and, in my experience, this variable dose technique does not work, unless morphine is prescribed and recorded on a chart specifically designed for this purpose, which is very different from the usual hospital medication chart (see figure). (This chart, a part of the monograph entitled The fixed interval, variable dose [FIVD] regimen, is available from the writer on request.)

Figure: Suggested chart for recording regular morphine medication.

When an adjuvant is used to potentiate the analgesic effect of morphine, a small initial dose should be given, regardless of the morphine dosage currently in force. For example, one should start with administering 10 mg of chlorpromazine [AA: but see earlier addendum] every eight hours, then increase the individual doses given to 25 mg, or occasionally, to 50 mg; similarly with diazepam - a dose of 2 mg every eight hours may be increased to 5 mg or 10 mg.

When possible, the oral route is preferred as being the most convenient and comfortable; it also causes less fluctuation in blood levels than do intermittent injections. Morphine is [AA: or was] available with tacrine in tablet form, which is convenient to store and administer, but morphine mixture allows for more flexibility in dosage and is easier for very ill patients to swallow.

Morphine mixture need only contain morphine hydrochloride and water, with colouring or flavouring as optional additives. This solution is stable for at least a month, although some additives result in a slight sediment or cloudiness which can be removed by a coffee filter. If a preservative is needed, I prefer metabisulphite, although the use of benzoic acid has also been suggested. Of the common alternatives, alcohol makes the mixture taste sickly and may irritate mouth ulcers or cause vomiting, while chloroform water also seems to cause irritation of the mouth, oesophagus or stomach in some patients, and is potentially hepatotoxic. If necessary, up to 200 mg of morphine hydrochloride may be dissolved in each 10 mL of water, and it is preferable to use a concentration which results in a dose volume of 15 mL or less. Obviously, the concentration of any morphine mixture must be clearly marked on the label. The addition of co-analgesic agents to the same mixture should be avoided, as tolerance does not develop at the same rate for each agent, and in any case, different patients require different proportions from the outset.

When little can be taken by mouth, morphine mixture may be given per rectum through a soft catheter, and co-analgesic agents can be given as suppositories. However, the best route for some patients who cannot take medication by mouth is continuous subcutaneous administration by means of a syringe driver, such as that previously marketed by Pye and now [AA: i.e. in 1985] by Graseby Dynamics.24 If an adjuvant is required, hyoscine may be mixed with the morphine in the syringe, and the mixture given by the subcutaneous route. Other combinations may necessitate intramuscular siting of the needle, and more frequent changes of sites.

Various other routes of morphine administration have been used and, of these, the epidural administration of morphine seems [AA: in 1985] the most promising.25,26

Whatever route is used, the timing of doses is of crucial importance. For the control of severe chronic pain there is no place whatsoever for "prn" medication5,27 - it does not control chronic pain, and sometimes makes it worse. Drugs used for alleviation of chronic pain must be given at regular intervals, so that the blood level of each drug always (day and night) remains within the therapeutic range for that patient. For many analgesic agents, including morphine, the right interval is about four hours. At high dose-levels, smoother control may be achieved with doses given every three hours. Vague instructions, like "qid", are disastrous: the interval is just as important as the number of doses. Once pain control has been achieved, it is often possible to omit one dose during sleep, by arranging the schedule so that the last dose of the day is given at bedtime, and by doubling this bedtime dose. However, if morning pain occurs, it is best to revert to a strict every-four-hours schedule; most patients go back to sleep quite easily after taking their medicine.

Side-effects

The main side-effects of opioids are nausea, constipation, drowsiness and confusion. Respiratory depression is rarely a problem in practice with the regimens described.5 Depression of affect is, however, likely after some weeks or months of treatment, and should be watched for.

Nausea or vomiting within five minutes of the oral intake of morphine often responds, in my experience, to omission of alcohol and chloroform water from the formula. Nausea caused by morphine itself is usually alleviated by the administration of 5 mg of prochlorperazine by mouth with each dose of morphine. Other measures include the administration of antiemetic combinations such as prochlorperazine with promethazine, [AA: or haloperidol with or without an antihistamine; or various newer antiemetics, either alone or in various combinations] the addition of co-analgesic agents or other modalities to allow reduction of the dosage of morphine, or the administration of morphine by a different route, as discussed above. Very rarely, patients respond with uncontrollable nausea and vomiting to any strong opioid. If they remain in pain despite other measures, an alternative method of pain control, such as cordotomy, should be urgently considered.

Constipation is completely preventable by the routine administration of laxatives with regular analgesic agents. All patients should receive a fibre supplement (for example, Fybogel) and the stool-softening agent, sodium sulphosuccinate. Most will also need a peristaltic stimulant such as danthron, and some will need a lubricant such as liquid paraffin [AA: as long as you are quite sure it will not end up in the patients lungs]. [AA: Carefully tailored doses of the osmotic laxatives often used to prepare the bowel for colonoscopy have also proved to be very useful.] Bowel actions should be charted meticulously, preferably on the same chart as the oral dosage of morphine. Rectal examination should be performed if there is any rectal discomfort, or after four days without a bowel action [AA: or sometimes earlier or later, depending on the holistic context]; packing of the rectum with firm or hard stool is an indication for an enema (a disposable phosphate enema is convenient) followed by manual removal of faeces if necessary. [AA: High impactions may require one or more treatments, each consisting of a one or two litre tap water enema, administered very slowly over one or two hours – preferably using an intravenous infusion set, or something similar, to control the rate of ingress of water via a soft catheter with its tip in the vicinity of the rectosigmoid lumen.] A rectum packed with soft stool is best evacuated with the high instillation of bisacodyl rectal solution through a flexible catheter. The importance of meticulous bowel care, especially for patients in the terminal phase of their illness, simply cannot be exaggerated.

Drowsiness is normal during the first three or four days of a regular opioid regimen, although some clinicians [AA: used to] choose to reduce it by the concomitant use of tacrine28 (as in the Mortha tablet). The possibility of drowsiness needs to be explained both to the patient and to relatives. It may also recur at times of significant increase in dosage. Although some patients complain about it, most prefer this state to uncontrolled pain.

Confusion is sometimes a difficult problem in the elderly patient, and a change of the opioid used does not always solve it. It may resolve after about a week; the usual methods of assisting orientation are helpful. [AA: The many other possible causes of confusion must obviously be excluded.]

Both drowsiness and confusion are more likely if a tranquillizer is used as an adjuvant, especially in high or frequent dosage or, in the case of chlorpromazine, for example, in the presence of reduced hepatic function. The intramuscular administration of diazepam also creates problems caused by erratic absorption, unless it is administered in the deltoid muscle.29 In my experience, these adjuvants are only occasionally necessary when the comprehensive approach to pain control is used.

Reassessment

All analgesic regimens need frequent reassessment. Doses must be strictly "titrated" by means of reports from the patient and attendants; they may need increasing or decreasing. No amount of knowledge or experience can substitute for regular review; this is especially true in the terminal phase of the illness.

Other factors affecting pain perception

The perception of pain is a complex phenomenon which is affected by the interaction of many factors. Many of these have been described, particularly in the literature dealing with the hospice-palliative care movement.6,30,31 Here, I simply wish to mention the main points.

First, various physiological factors interact with the perception of pain: the control of other symptoms, such as vomiting, dyspnoea, cough or disagreeable odours, raises the pain threshold considerably; so does the provision of adequate rest and sleep. Nutrition and appropriate exercise are also relevant; and a true anxiety state or depressive illness must be treated if present.

Second, hypophysectomy has been shown to relieve pain in malignant disease, regardless of hormone dependence,32 and this therapeutic option, though not completely understood, should not be forgotten. [AA: However, as mentioned above, recent developments in the management of neuropathic pain, such as spinal cord stimulation and neuromodulation of the cingulum, have largely superseded some of the earlier neurosurgical pain control techniques.]

Finally, and of tremendous importance, are other factors which influence pain perception and can be loosely grouped under the heading "peace of mind". Uncertainty breeds anxiety which, in turn, lowers the pain threshold. Uncertainty is dispelled by gentle, but honest, explanation, preferably by the patient's doctor. Environment is also important, the patient's home being preferred, where possible. A high standard of general nursing care is essential for dependent patients. The attitudes of the care-givers are equally important, and here teamwork and staff support are essential. Especially in the later stages, patient and family together should constitute the entity receiving care. Family communication problems, and especially a "conspiracy of silence" regarding diagnosis, can thwart the most expertly conceived analgesic regimen. Bottled-up emotions, such as anger, grief, and fear, may also prevent pain control - in such cases, gentle encouragement to explore and express these feelings is essential.6 The importance of various types of "unfinished business" has been described elsewhere.e33 [AA: Also see Coates, G.T. 07 May 2008. Wanterfall: A practical approach to the understanding and healing of the emotions of everyday life. Free e-book from Wanterfall eBooks] Chaplaincy services are frequently required, and it must be borne in mind that patients who are not "religious" may also have spiritual needs. Various specific techniques, such as relaxation training, acupuncture, hypnotherapy, diversional therapy and music therapy, have also been shown to raise the pain threshold.6

Conclusion

Increasing experience has shown that cancer pain can almost always be controlled if the standard diagnostic and therapeutic techniques described above are applied. However, it must be borne in mind that there is often more than one cause for pain; that more than one therapeutic modality is often required in management, especially in the case of terminally ill patients; that success may often depend on the many non-specific factors; and that continual review of the patient's needs is an absolute necessity.

References

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2. Bonica JJ. Cancer pain: a major national health problem. Cancer Nursing 1978; 1: 313-316.

3. Parkes CM. Evaluation of family care in terminal illness. In: Pritchard ER, Collard J, Orcutt BA, et al. eds. The family and death. New York: Columbia University Press, 1977.

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11. Baines M1. The medical management of malignant bowel obstruction. (Presented at 4th International Conference on terminal care, McGill University/Royal Victoria Hospital Palliative Care Unit, Montreal, Canada, October 1982). New York: Audio Video Transcripts, 1982 (cassette tape).

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21. Flannigan GM, Clifford RPC, Carver RA, et al. Indomethacin: an alternative to pethidine in ureteric colic. Br J Urol 1983; 55: 6-9.

22. Twycross RG. Clinical experience with diamorphine in advanced malignant disease. !nt J Clin Pharmacol 1974; 9: 184.

23. Twycross RG, Wald SJ. The long-term use of diamorphine in advanced cancer. In: Bonica JJ; Albe-Faescard D, eds. Advances in pain research and therapy. Vol. 1. New York: Raven Press, 1976: 653.

24. Dickson RJ, Russell PSB. Continuous subcutaneous analgesics for terminal care at home. Lancet 1982; 1: 165.

25. Torda TA, Pybus DA. Clinical experience with epidural morphine. Anaesth Intensive Care 1981; 9: 129-134.

26. Cherry D. Epidural narcotics. Paper presented at the Australian Pain Society Annual Scientific Meeting, 1984.

27. Tempest SM, Clarke IMC. The control of pain. 1. By drugs; 11. By non-drug methods. In: Wilkes E, ed. The dying patient. Lancaster: MTP Press Limited, 1982.

28. Stone V. Moon W, Shaw FH. Treatment of intractable pain with morphine and tetrahydroaminacrine. Br Med J 1961; 1: 471-473.

29. Divoll M, Greenblatt DJ. Absolute bioavailability of oral and intramuscular diazepam (Abstract). Clin Pharmacol Ther 1981; 29: 240.

30. Saunders C, ed. The management of terminal disease. London: Edward Arnold, 1978.

31. Ajemian 1, Mount B, eds. The Royal Victoria Hospital manual on palliativelhospice care. Salem: Ayer, 1982.

32. Gonski A, Sackelariou R. Cryohypophysectomy for the relief of pain in malignant disease. Med J Aust 1984; 140: 140-142.

33. Kubler-Ross E. On death and dying. New York: Macmillan, 1969.

34. Brophy T. Pain relief in general practice: 2. Management of intractable pain. Curr Ther 1980; 21 (Aprill: 37-49.

(Received April 11, 1983; accepted October 5, 1984)

Appendix
Equivalent doses of opioids

These have been combined, and in some cases extrapolated, from figures published by Twycross,5 Houde,15 Brophy,34 and others. They are useful only as a starting point when changing analgesic therapy; there is much variation between individual patients, as well as between published studies. Half-lives also vary from one agent to another. [AA: More recent equivalent dosage tables may provide more detailed guidance. However, there is no such thing as an accurate dosage equivalence table. Therefore, doses must always be titrated on the basis of frequent review of the patient's response after changing from one medication  or dose form to another.]

 

The following parenteral and oral doses of strong opioids are roughly equivalent to 10 mg of morphine administered by intramuscular injection (IMI) [AA: or subcutaneous injection (SCI)], and thus to each other:

Morphine 10 mg IMI or 30 mg oral

Heroin 5 mg IMI or 15 mg oral

Methadone 10 mg IMI or 20 mg oral

Oxycodone 15 mg IMI or 30 mg oral

Dextromoramide 5 mg IMI or 10 mg oral

Pethidine 75 mg IMI [rarely appropriate]

 

The following oral doses of various opioids have a mild to moderate analgesic action and are roughly equivalent to 1.5mg [AA: one and a half milligram] of morphine administered by IMI [AA: or SCI], and thus to each other:

Dextropropoxyphene HCl 65 mg

Pethidine 50 mg

Codeine 30 mg

Pentazocine 25 mg

Oxycodone 5 mg

Morphine 5 mg

Methadone 3 mg

Dextromoramide 1.5 mg

 

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Declaration of Interest

Dr Coates receives no financial or other incentives from any provider of goods or services used in the management of cancer pain.

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