Exploring the causes of chronic cancer pain and possible remedies
Authors: Mike Fillon
Journal: CA A Cancer Journal for Clinicians (2020)

…based upon my own experience, patients sometimes feel embarrassed or ashamed to mention that they continue to have pain, out of stigma and concern about being labeled as medication seeking.”–Nina Niu Sanford, MD With a growing number of cancer patients and survivors, and continued alarm regarding the opioid crisis, a new study in Cancer (2019;125:4310-4318. doi:10.1002/cncr.32450) examines how widespread chronic pain is among cancer survivors and the psychological and functional problems associated with chronic pain. “To the best of our knowledge, this is the first comprehensive study assessing the rate of chronic pain among cancer patients and survivors,” says Nina Niu Sanford, MD, an assistant professor of radiation oncology and Dedman Family Scholar in Clinical Care at the University of Texas Southwestern Medical Center in Dallas, Texas. “The prevalence of chronic pain among this population was quite high at about one-third and was associated with worse psychological and functional outcomes.” Data for the study were drawn from the National Health Interview Survey (NHIS) Cancer Control Supplement, which is co-sponsored by the Centers for Disease Control and Prevention and the National Cancer Institute, primarily to monitor progress toward nationwide cancer control objectives. Although this survey includes information regarding a broad range of general and cancer-related risk factors, health behaviors, and health outcomes, for the current study the researchers focused on how often participants experienced pain over the most recent 3-month period, with possible responses including never, some days, most days, every day, and unknown. The survey noted whether participants had received a cancer diagnosis and, if so, when and what type; survivors of nonmelanoma skin cancer were excluded from the study for consistency with prior studies, as were patients diagnosed fewer than 2 years prior to the interview to avoid confusion between chronic pain and acute pain related to treatments and medical procedures. Participants also were asked if and how often they were depressed, worried, nervous, or anxious, with possible responses being daily, weekly, monthly, a few times a year, never, or did not know. Subjects also were asked if they had missed work because of health issues and whether they needed help with activities of daily living (ADLs; eg, eating, dressing, walking or transferring from one position to another, bathing, toileting, and maintaining bowel and bladder continence) and/or instrumental ADLs (8 activities such as food preparation, housekeeping, handling finances, and medications). After applying all inclusion and exclusion criteria, a total 115,091 participants remained, 7565 (6.6%) of whom were cancer survivors. The median age of the participants who reported a cancer history was 68 years, whereas the median age of those who had never been diagnosed with cancer was 47 years (P < .001). Researchers found that the prevalence of chronic pain (defined as that occurring daily or on most days) among cancer survivors was nearly double that for individuals without a cancer history (30.8% and 15.7%, respectively). Females reported chronic pain more often than males (18.3% and 14.8%, respectively). The researchers found that older age increased the odds of chronic pain only in participants without cancer. Chronic pain was reported by 23.2% of those without cancer who were older than the median age of 48 years compared with by 10.1% of those younger than the median age (P < .001), whereas the prevalence of chronic pain among cancer survivors was similar among those older versus younger than the median age (31.1% vs 30.7%, respectively). Among cancer survivors, those with sarcoma were found to have the highest prevalence of chronic pain. Compared with those participants without a cancer diagnosis, chronic pain was significantly more common among survivors of all cancer types except for bladder, prostate, and breast cancers. Cancer survivors who reported chronic pain were significantly more likely to report several adverse psychological and functional outcomes compared with survivors without chronic pain. Among cancer survivors, chronic pain was significantly associated with the prevalence of depression (32.8% vs 11.1% for survivors with and without chronic pain); feeling worried, nervous, or anxious (44.7% vs 22.8%); inability to work because of health problems (32.5% vs 7.7%); and needing assistance with ADLs (10.6% vs 2.5%) or instrumental ADLs (19.6% vs 5.2%). “We have known for decades that our cancer therapies are associated with pain both during and beyond completion of therapy,” says Kevin C. Oeffinger, MD, founding director of the Duke Cancer Institute Center for Onco-Primary Care and director of the Duke Supportive Care and Survivorship Center at the Duke Cancer Institute in Durham, North Carolina. “However, the comprehensive view that Sanford and colleagues took, using NHIS data, was an interesting way to compare cancer survivors and noncancer patients.” According to Dr. Oeffinger, the single greatest limitation in NHIS data is the lack of information regarding each patient's treatments. “That may be why they didn't see the changes with breast and prostate [cancers] since we don't know which patients underwent chemotherapy and with what regimens—if they were treated with taxanes or not and so on. They all get mixed into the same group,” he said. “Still, they had some interesting associations which confirmed…associations we have seen or suspected, and they documented that chronic pain is an immense problem.” Dr. Sanford says she and the research team believe the study will help to make clinicians aware of the high prevalence of chronic pain, even many years into cancer survivorship, and that they should screen for it. “They may be surprised that their patients are continuing to experience pain and are taking medications to address [it],” she says. However, by bringing up the topic, physicians may help patients to feel more comfortable discussing it. “Based upon my own experience, patients sometimes feel embarrassed or ashamed to mention that they continue to have pain, out of stigma and concern about being labeled as medication seeking,” Dr. Sanford says. “For researchers, better strategies for pain management should be explored, including those not reliant on opioid medications.” Dr. Oeffinger agrees. “The primary care providers, including nurse practitioners and physician assistants, are critical in assessing and managing patients' pain during therapy. They know their patients, they know the patient dynamics, they know the patients' resources, and that's an underutilized resource from the oncology perspective that we don't tap into nearly as often as we should.” “We don't do a good job, in general, of managing pain in the US,” Dr. Oeffinger adds. “And that's especially unfortunate in this population [cancer survivors], which has an increased risk of pain.” Dr. Oeffinger says he is a great believer in an array of nonpharmacologic approaches to pain management, including the right form of exercise. “There definitely is a place for opioids, but we need to be careful that we're managing and treating the pain appropriately.” Nevertheless, Dr. Sanford says she is hopeful that shedding light on the prevalence and impact of chronic pain may help to open lines of communication between physicians, patients, and policymakers and provide a benchmark with which to evaluate the efficacy of any future policy changes. For further information regarding the care of cancer survivors, Dr. Oeffinger recommends the National Cancer Survivorship Resource Center toolkit (smhs.gwu.edu/gwci/survivorship/ncsrc/national-cancer-survivorship-center-toolkit), developed by the American Cancer Society and the George Washington University Cancer Center, and the American Society of Clinical Oncology's Survivorship Compendium (asco.org/practice-policy/cancer-care-initiatives/prevention-survivorship/survivorship/survivorship-compendium?).