View Cancer Pain as a ‘Pathogenic Agent’ to be Treated, Expert Says

COLUMBUS, Ohio--Cancer pain must be viewed as a "pathogenic agent" in its own right as well as a symptom of cancer or its treatment, said Costantino Benedetti, MD, director of the Palliative Medicine-Hospice Program, Ohio State University, Arthur G. James Cancer Hospital and Research Institute.

Intense pain may cause anorexia, nausea and vomiting, insomnia, weakness, depression of the immune system, and psychological depression, he said at a pain conference sponsored by the Ohio State University Medical Center. Using data extrapolated from major published studies, Dr. Benedetti said that 51% of cancer patients experience pain. Of that group, 20% have mild pain, 50% have moderate to severe pain, and 30% have severe to excruciating pain.

Although the World Health Organization (WHO) stated in 1986 that 85% to 90% of patients with cancer pain can be effectively treated, Dr. Benedetti said, studies show that only 41% of cancer pain patients are actually experiencing adequate relief from pain. That figure is even lower for patients with advanced cancer: Only 25% report relief from pain.

"This discrepancy is a human rights violation," Dr. Benedetti said. (See illustration.) It is all the more distressing because a number of clinical guidelines for cancer pain management are available for clinicians, including guidelines from WHO and the US Agency for Health Care Policy and Research (AHCPR).

Barriers Persist

Barriers to proper cancer pain therapy persist, however. Dr. Benedetti cited a lack of education in health care professionals and the public as "probably the most important factor." Deficiencies in teaching about pain and its therapy begin in medical school and continue at the postgraduate level, he said.

He added that some physicians mistakenly believe that appropriate pain relief will mask any new pathologic event. In fact, any new pathology will increase pain levels beyond what the patient’s current medication dosage can control.The public also fails to realize that pain can be effectively treated and that suffering from cancer pain is needless, Dr. Benedetti said. For some patients, cost is a barrier to pain relief. The cost is $250 a month for oral cancer pain medication for the average patient at the Arthur G. James Cancer Hospital. Medicare fails to cover the cost of pain medications unless they are injectable, he said.

Better Pain Assessment

Better pain assessment can help clinicians treat pain. The clinical practice guidelines of AHCPR recommend using a pain intensity scale, Dr. Benedetti said. Several easy-to-use scales are available. The Visual Analog Scale (VAS) is a 10-cm line extending from "No pain" to "Pain as bad as it could possibly be." He noted, however, that it is used primarily for research and is cumbersome for use at the bedside.

A 0-to-10 Numeric Pain Intensity Scale permits patients to choose a number corresponding to their degree of pain. The Simple Descriptive Pain Intensity Scale provides five descriptions of pain, none, mild, moderate, severe, and worst possible pain, for patients to choose from.

Making Pain Visible

"Patients must be able to tell us how much pain they have and if it’s bearable," he said. Indeed, to be properly treated, pain must be made visible. This is why there is now a movement to make pain the fifth vital sign. "In our institution, pain is now assessed whenever the four vital signs (heart rate, respiratory rate, blood pressure, and temperature) are measured," Dr. Benedetti said.

Cancer pain is a "dynamic" process. It changes in severity, quality, and causes, he said. As a result, patients must be followed closely and therapy changed as needed to control pain.

Patient medication must be individualized to the patient, Dr. Benedetti said. Pain patients should receive the proper analgesics at the appropriate dose and delivered by the appropriate technique.

Clinicians should follow the WHO analgesic ladder, he said. It recommends a non-opioid (aspirin, acetaminophen, or an NSAID) for mild pain. When pain increases, add an opioid and increase the dose as needed. If a patient reports moderate to severe pain, he or she should be started on an appropriate dose of an opioid medication. Doses should be given on a regular basis, "by the clock," with additional doses as needed, he said. Adjuvant drugs and physical and psycho-social modalities can be used concurrently with opioids to improve pain relief.

The WHO ladder shows "freedom from cancer pain" as the goal of pain treatment. But this is sometimes impossible, Dr. Benedetti said, because of unbearable side effects caused by high doses of opioids. In that case, he said, the goal is to bring intolerable pain to a level that is tolerable to the patient while keeping side effects to a minimum.

If this cannot be accomplished with oral, transdermal, or parenteral agents alone, the use of invasive techniques, such as intraspinal opioids, or selective neurolytic blocks, such as celiac plexus block, can provide effective pain relief with significantly fewer side effects.

He also disagrees with the WHO’s recommendation of "weak opioids" in the second step of the ladder. He said that recommendation may have been necessary because many countries lack access to strong opioids. However, for countries where oxycodone, morphine, and hydromorphine are available, the use of weak opioids, such as codeine, is not indicated, because the side effects profile of codeine is worse than that of the stronger opioids.