Is pain or dependency driving elevated opioid use among long-term cancer survivors?

September 6, 2017|Oncology Practice

Rates of opioid prescribing were about 1.2 times higher overall among cancer survivors up to 10 years after diagnosis, compared with matched controls, with more than threefold higher rates of opioid prescriptions for survivors of some cancers, according to a Canadian population-based cohort study.

Searching for the cause of these elevated rates reveals the complexity of the survivorship experience, and may also point the way to areas where there’s work to be done, according to physicians whose practices touch the lives of cancer survivors.

In a retrospective matched cohort study of participants in the Ontario Health Insurance Plan and the Ontario Drug Benefits Program, Rinku Sutradhar, PhD, of the University of Toronto, and her colleagues, identified patients aged 18-64 who had a cancer diagnosis at least 5 years previously. Patients were included only if they had not had a cancer recurrence or another malignancy. When compared 1:1 to age- and sex-matched controls, the 8,601 cancer survivors had a relative rate of opioid prescribing of 1.220 (95% confidence interval [CI], 1.209-1.232), the investigators reported (Cancer 2017 Aug 17. doi: 10.1002/cncr.30839).

Opioid prescribing rates varied according to the type of cancer the survivor had had, with a relative rate of 3.119 for noncolorectal gastrointestinal cancer survivors and a rate of 2.066 for lung cancer survivors. Individuals with nonprostate genitourinary cancers had a prescribing rate of 1.619. All of these differences were statistically significant.

Elevated prescribing rates were not seen in patients with brain, breast, colorectal, head and neck, or prostate cancers. The relative rate of prescribing for hematologic cancers was 1.383, a difference that approached, but did not quite reach, statistical significance (P = .0512).

When multivariable analysis was used to stratify individuals by length of time since cancer diagnosis, a significantly elevated relative rate of opioid prescribing persisted; for those 5-10 years from diagnosis, the relative rate was 1.190 (95% CI, 1.040-1.362, P = .011), while for those diagnosed at least 10 years ago, the relative rate was 1.244 (95% CI, 1.090-1.420; P = .00118).

Multivariable analysis was also used to control for income, rural residence, and comorbidities. However, the study could capture only opioids that were obtained with a prescription, and could not track whether medications were taken by the person for whom they were prescribed, Dr. Sutradhar and her colleagues said.

Cancer survivors may have a higher prevalence of chronic pain than the general population for reasons related both to their initial diagnosis and the sequelae of treatments such as surgery, chemotherapy, and radiation therapy, the investigators noted, adding, “it is also possible that a higher rate of opioid prescribing among survivors is due to a dependency that originated from opioid use earlier in the disease trajectory.”

Because of the potential for opioid use disorder and the many adverse effects that can be associated with long-term opioid use, they said, “primary care providers who treat cancer survivors should be encouraged to critically examine reasons for lingering opioid use among their patients.”

The oncologist’s perspective

Walter M. Stadler, MD, an oncologist who treats genitourinary and hematologic cancers, also wonders whether it’s pain or dependency that’s driving the increased prescribing rates in cancer survivors.

“If you see these differences in opiate prescribing, is that because they are having pain, and more pain than we recognized in the past, or is this due to inappropriate long-term prescribing in patients who essentially may not have that much more pain, but have become dependent on these drugs?” asked Dr. Stadler, director of the genitourinary program at the University of Chicago’s Cancer Research Center. “Either one is in essence a problem … but we don’t know what the underlying cause may be. We can’t tell that from this particular study,” said Dr. Stadler, who also serves as the hematology/oncology section chief at the university.

One opportunity to reassess which medications and treatment modalities are appropriate for the cancer survivor, said Dr. Stadler, is at the point of discharge from oncology care, which usually happens at about the 5-year mark for patients with no evidence of disease. Survivorship has received more attention since the 2005 Institute of Medicine report calling for increased attention to cancer survivors’ ongoing care. However, he said, “it’s not clear that we do a very good job in terms of educating either the patient or their primary care physician in regards to the kinds of things that we expect, the kinds of things that need to be done, or even a good summary of the therapy that was provided.”

There are resources that can help, he said. “That’s why organizations like [the American Society for Clinical Oncology] have put together some more formal survivorship plans that should be provided when patients are transitioned.”

The realities of clinical life can get in the way of implementation, though. Oncologists are already stretched thin, and most electronic health record systems don’t integrate well with survivorship documentation. Finding staff who can spend the time to gather and package all the necessary information can also be a problem: “People are expensive, and none of us have extra cash lying around,” said Dr. Stadler.

Still, he said, “like a lot of good papers, this raises some issues and areas for further investigation.” First, he said, physicians must assess whether cancer survivors are having chronic pain, and then sort things out from there. “What are the pain syndromes – and what are we doing about them? – because it’s not something that’s been well addressed.”