The opioid epidemic imposes scrutiny on clinicians and patients alike; with particular emphasis on cancer survivors who require the drugs to manage their pain. How does the clinician determine who is at risk for persistent opioid use and abuse? A group of radiation oncologists and pain specialists from the University of California San Diego (UCSD) conducted a study to answer this vital question, and presented their findings at the 2019 American Society for Radiation Oncology (ASTRO) Annual Meeting, held in Chicago.1
More than 50% of oncology patients who receive curative treatment suffer from moderate to severe pain that can be relieved by opioids, according to WHO pain guidelines.2 Although these medications are accepted for relief of such acute pain, their use in situations where patients have chronic pain (lasting for more than 3 to 6 months) is not so well defined. There are risks of such long-term administration, such as medication tolerance and loss of efficacy over time. The potential of toxicity can lead to conditions such as depression, difficulty concentrating, and sedation, and the patient may also develop hyperalgesia or hypogonadism. There are also the well-known risks of dependence, misuse and abuse, and accidental overdose. The authors of this study support adopting the clinical practice guideline of the American Society of Clinical Oncology (ASCO) when using opioids to achieve optimal pain management, using risk mitigation strategies such as judicious opioid use, drug screening, adherence monitoring, and strategies for alternative pain management.1,3
Creating a Risk Score
The radiation oncologists sought to identify clinical risk factors and create a risk score, utilizing an evidence-based risk stratification approach to identify patients who might benefit from a proactive approach by the oncology nurse or other clinician. Their efforts resulted in the Cancer Opioid Risk Tool, a validated prediction tool for assessing the risk of persistent opioid use 1 to 2 years after treatment, estimating risk as low (less than 5%), intermediate (5% to 25%) and high (greater than 25%).
The researchers used the Veterans Affairs (VA) Informatics and Computing Infrastructure (VINCI) database, which contains detailed electronic health record information on all veterans within the VA health care system. This database provided data on 106,732 veteran cancer survivors whose cancer had been diagnosed between 2000 and 2015.1
Common diagnoses among the VA patients were 1 of 12 noncutaneous, nonhematologic malignancies, including cancer of the bladder, breast, colon, esophagus, head and neck, kidney, liver, lung, pancreas, prostate, rectum, or stomach. The study group included patients who were treated with surgery, radiation therapy (RT), or both and who were alive without disease recurrence 2 years after treatment had begun.1
Two models of the Cancer Opioid Risk Tool are available on the website: Full and Lite. Using an automated algorithm, the risk for persistent opioid use is calculated based on data entered by the clinician. The lite model uses 5 variables: age, presence of depression, alcohol abuse, prior opioid use, and whether treatment included chemotherapy. The more complex, full, model uses these 5 variables plus employment status, psychiatric diagnoses, race, tobacco use, body mass index (BMI) category, type of cancer, disease stage, and local treatment. (Note, although improvements to the tool are ongoing, it is totally functional.) The full version is recommended if providers have time and access to all of the relevant information.
Risk Factors for Persistent Opioid Use
The radiation oncologists determined that the rates of persistent posttreatment opioid use among the VA cohort varied by type of cancer and prior opioid use. Significant findings included:
- Patients with prostate cancer patients had the lowest rate of opioid use (5.3%).
- The highest rate of opioid use (19.8%) was observed in patients with liver cancer.
- The main variable for persistent opioid use after cancer treatment was the patient’s history of opioid use before a cancer diagnosis. 1
Risk factors first reported in the San Diego study were younger age, white race, BMI, unemployment at the time of cancer diagnosis, lower median income, use of chemotherapy, increased comorbidity, and tobacco use. Substantially increased odds of persistent opioid use were associated with patients who had a history of prior alcohol abuse, nonopioid drug abuse, chronic or intermittent opioid abuse, and depression.1
Study limitations included whether research on mostly male military veterans would translate to a civilian population of both sexes. Also, veterans who saw combat were exposed to mental and physical trauma at higher rates than the general population, and this could increase their risk for opioid dependence or abuse. Furthermore, this population is more likely to have health insurance and are therefore less likely to be financially insecure than the general population.1
Managing patients at risk
The authors note that the absolute rate of persistent opioid use, abuse, and dependence was relatively low among the cohort of VA cancer survivors, especially among those who were opioid-naïve. They believe that improved risk stratification will allow for personalized risk assessment and improve the safety of pain management in cancer survivors. The lite model of the Cancer Opioid Risk Tool was validated in an independent test cohort. A more robust validation of the newer full tool will require a prospective study.
Strategies that can help clinicians better manage patients at risk of persistent opioid use include establish a signed treatment agreement, utilize periodic urine drug testing, educate patients and their caregivers on the risks of abuse and/or misuse, offer referrals to pain and palliative medicine specialists, and avoid high risk formulations while minimizing lower total daily medication doses.
1. Vitzthum LK, Riviere P, Sheridan P, et al. Predicting persistent opioid use, abuse and toxicity among cancer survivors [published online November 22, 2019]. J Natl Cancer Inst. doi: 10.1093/jnci/djz200
2. World Health Organization. Cancer Pain Relief : With a Guide to Opioid Availability. 2nd ed. Geneva, Switzerland; 1996. https://apps.who.int/iris/bitstream/handle/10665/37896/9241544821.pdf?sequence=1&isAllowed=y. Accessed January 13, 2020.
3. Paice JA, Portenoy R, Lacchetti C, et al. Management of chronic pain in survivors of adult cancers: American Society of Clinical Oncology Clinical Practice Guideline. J Clin Oncol. 2016;34(27):3325-3345.
This article originally appeared on Oncology Nurse Advisor