Managing cancer pain: Frequently asked questions

HOW IS CANCER PAIN MANAGED IN PATIENTS WITH ORGAN FAILURE?

Given the prevalence of chronic illnesses such as diabetes, hypertension, and heart failure, cancer patients are likely to have some degree of hepatic or renal dysfunction. As most pain medicines are metabolized or excreted hepatically or renally, knowledge about how pain drugs affect these organ systems or vice-versa has become more important in the prevention of drug toxicity. Table 8 lists the dosage adjustments needed for various pain drugs used for chronic pain.^32–34

• Opioids that can be used in liver failure or cirrhosis: morphine, hydromorphone, methadone, levorphanol, buprenorphine.
• Opioids that can be used in renal failure: methadone, fentanyl, and buprenorphine are safest; oxycodone and hydromorphone are moderately safe; morphine is the least safe.^35,36
• Opioids that can be used in both kidney and liver failure: methadone, buprenorphine.

HOW CAN PROBLEMS RELATED TO SUBSTANCE ABUSE BE AVOIDED?

Substance abuse is less a problem in managing cancer pain than in chronic nonmalignant pain. Prescribing opioids safely is challenging, and very little has been published on substance abuse and the management of cancer pain. However, in the absence of practice guidelines, the best approach is to establish a dosing structure, control prescription refills, and monitor the patient.

Abuse is the misuse of an opioid via self-titration or altering the dosing schedule or route of administration. Patients who misuse opioids—ie, take them differently than prescribed—are not necessarily addicted.

Addiction is the abuse of a drug associated with psychological dependence, despite harm.

Diversion can occur without addiction and is done for financial gain, and this is the worst offense as it may harm others.

Pseudoaddiction is abnormal, demanding, often hostile behavior resulting from uncontrolled pain; once the pain is controlled, the behavior resolves.

Behaviors such as forging prescriptions, stealing or borrowing drugs, frequently “losing” prescriptions, and resisting changes to medication despite adverse effects are more predictive of addiction than are behaviors such as aggressive complaining about the need for more drugs, drug-hoarding, and unsanctioned dose escalations or other forms of noncompliance, as the latter three are more likely to indicate poorly controlled pain.³⁷

Predictors of opioid abuse include a family history or a personal history of alcohol or drug abuse (including prescription drugs); a history of psychiatric illness (including anxiety disorder); male sex; nonwhite race; a history of driving under the influence of alcohol or drugs; a record of drug-related convictions; lost or stolen prescriptions; and using supplemental sources to obtain opioids.³⁸ Socioeconomic status and disability level were not found to be significant predictors.³⁸

Different scales are available to predict the risk of aberrant drug behavior in patients on chronic opioid therapy. Of the many available, the Screener and Opioid Assessment for Patients With Pain and the Current Opioid Misuse Measure assess all the key factors.³⁸

After an assessment, the next step is monitoring. Unfortunately, no specific method has been validated. In one study, urine toxicology testing was more effective at identifying problems than monitoring patient behavior alone, and monitoring behavior alone would have resulted in missing about half of the patients with a problem.³⁹ The same study showed that even in the absence of aberrant drug-related behavior based on predictors, a significant number of urine toxicology screens were positive.³⁹

A negative urine screen for the patient’s opioid suggests diversion. The clinician should order a screen for the prescribed opioid because a general screen may not detect nonmorphine opioids. A general screen may detect polysubstance abuse, which is common in individuals with addiction.

The effective management of patients with pain who engage in aberrant drug-taking behavior necessitates a comprehensive approach to manage risk, treat pain effectively, and assure patient safety.⁴⁰ “Pain contracts” are important as they set the stage for expected behaviors and urinary screens. Frequent visits and established limits such as a single prescriber, one pharmacy, no early refills, and urine drug screens help to minimize abuse.

Table 9 summarizes a strategy to manage opioid therapy in patients with history of substance abuse.⁴⁰

WHAT IS THE ROLE OF COMPLEMENTARY AND ALTERNATIVE THERAPIES?

Complementary and alternative medicine therapies are commonly used by cancer patients, with an average prevalence rate of 31%.^41–43 As the names suggest, they have been used both as an alternative to and as a complement to conventional medicine. Practitioners of complementary and alternative medicine emphasize its holistic, individualistic, empowering, and educational nature.

Patients do not routinely ask their physicians about these therapies,⁴⁴ and physicians often have only a limited knowledge of them.⁴⁵ Surveys of North American physicians showed that they view certain of these therapies as legitimate and effective.^46,47

The role of complementary and alternative medicine in cancer pain has been the subject of debate, as relatively little is known about adverse effects and drug interactions. Nevertheless, the American Cancer Society and the National Comprehensive Cancer Network guidelines on cancer pain recommend nonpharmacologic treatment be added for patients who report a pain score of 4 or greater on a 10-point scale after analgesic adjustment.^48,49

Most studies of complementary and alternative therapies for cancer pain are of poor quality, with significant shortcomings in methodology and study design and with no clear definition of outcomes.⁵⁰

Acupuncture is probably the most studied of these therapies, but clinical trials so far have not shown it to be an effective adjunct analgesic for cancer pain.⁵¹ A placebo-controlled, blinded randomized trial using auricular acupuncture showed a pain score decrease of 36% from baseline at 2 months compared with controls.⁵²

Studies involving cognitive therapy, supportive psychotherapy, and hypnosis showed modest benefit.^53,54 Two trials involving relaxation and imagery reduced cancer pain compared with controls.^55,56

Studies of massage therapy have shown mixed results; two studies reported a significant reduction in pain immediately after intervention, and no study found pain relief after 4 weeks.^57–60 Studies involving Reiki and touch therapy were inconclusive.^60,61

Music therapy has been used to treat patients physically, psychologically, socially, emotionally, and spiritually, with evidence still equivocal. A large prospective observational study involving 200 patients conducted by Gallagher et al⁶² showed pain was reduced by 30% after music therapy intervention. The same study showed a reduction in depression and anxiety.⁶² Music therapy could be used as a component of a multimodal approach to pain.

Herbal preparations are often used to treat cancer and symptoms by patients and naturalists. Some herbal medicines are known to cause toxicity in cancer patients. Examples are PC-SPES, mistletoe, and saw palmetto.⁶³

At this juncture, there is some evidence that some complementary and alternative therapies can relieve cancer pain, and the most promising therapy seems to be related to mind-body medicine (eg, biofeedback, relaxation techniques). But before we can legitimately integrate these therapies into the management of cancer pain, we need large randomized controlled trials to determine if they are effective in patients on chronic high-dose opioids and if they decrease the need for opioids.