Risk Factors for Opioid Misuse Identified in Cancer Patients

Roxanne Nelson, RN, BSN

December 02, 2019

Because pain is commonly associated with cancer, clinical questions understandably arise: Are patients with cancer especially at risk for opioid dependence or misuse? Can related risk factors be identified?

A new study of US military veterans has found that the overall incidence of persistent post-cancer treatment opioid use was 8.3% and was highest in patients who were previously chronic users.

Importantly, the authors identified factors associated with the risk of persistent opioid use, including younger age, white race, and increased comorbidity.

"Our study attempts to create an objective clinical tool that can help give providers a better understanding of a patient's risk of opioid-related toxicity," study author Lucas K. Vitzthum, MD, resident physician in the Department of Radiation Medicine and Applied Science at the University of California San Diego, said in a statement. "Ultimately, clinical tools such as ours could help providers identify which patients could benefit from alternative pain management strategies or referral to pain specialists."

The study was published November 22 in the Journal of the National Cancer Institute.

The opioid crisis has been in the mainstream media for several years now, and the misuse of these agents is a national crisis. One recent study found that being a patient with cancer was associated with a much lower risk for opioid-related death in comparison with the general population. Other research showed that 10% of patients who had surgery that was expected to cure the cancer were still filling opioid prescriptions 1 year after that surgery, with daily opioid doses similar to those in long-term opioid users.

Risk Factors Identified, Risk Score Created

In the current study, Vitzthum and colleagues sought to identify clinical risk factors as well as create a risk score that could help identify patients with cancer who might be at risk of persistent opioid use and abuse.

Using the Veterans Affairs (VA) Informatics and Computing Infrastructure (VINCI) database, they selected a cohort of 106,732 cancer survivors who received a diagnosis between 2000 and 2015. The patient population included patients with cancer who were treated with definitive local therapy (surgery, radiation therapy, or both) and who were alive without recurrence 2 years after they began treatment.

The primary endpoint was persistent opioid use that was defined as having filled 120 or more days' supply or 10 or more opioid prescriptions from 1 to 2 years following the initiation of curative treatment. Secondary endpoints included diagnoses of opioid abuse or dependence and hospital admission for opioid abuse.

There was considerable variation by cancer type, ranging from a high of 19.8% for liver cancer and a low of 5.3% for prostate cancer.

Persistent opioid use varied substantially by a history of opioid use before being diagnosed with cancer. Rates were lowest for those who had never used opioids (3.5%), next highest for prior intermittent users (15%), and highest among prior chronic users (72.2%).

Among patients who were opioid naïve, the variation in rates was associated with whether or not opioids were given during the diagnostic and treatment period. Patients who received opioid drugs during that time had rates of persistent posttreatment use of 6.2% vs 1.5% for patients who did not receive a prescription.

Opioid abuse or dependence occurred in 2.9% of patients and opioid-related admissions occurred in 2.1%.

The authors also identified several factors that were associated with the risk of persistent opioid use. These included younger age, white race, increased comorbidity, being unemployed at the time of diagnosis, lower median income, and current or prior tobacco use.

In addition, a previous diagnosis of alcohol or non-opioid drug abuse, opioid abuse, and depression were associated with higher odds of persistent opioid use.

In a release, study coauthor James D. Murphy, MD, also from the University of California San Diego, noted that "opioids play an important role in helping patients with pain from cancer, or pain because of treatment. Despite this important role, opioid use carries a risk of problems related to long-term use or abuse. From a healthcare provider perspective, we need better approaches to identify cancer patients at risk of these opioid-related problems."

Weighing In

Approached by Medscape Medical News for an independent comment, several experts gave their thoughts on the study.

These data can be useful for clinicians when caring for cancer survivors, explained Lesly A. Dossett, MD, MPH, assistant professor in the Department of Surgery and the Institute for Healthcare Policy & Innovation, University of Michigan, Ann Arbor. "The score could be used early in the treatment course to identify patients at high risk for persistent opioid use," she said. "If patients were at high risk, proactive education and counseling as well as avoiding high risk prescribing patterns may help to avoid persistent use or abuse."

She doesn't believe that clinicians are necessarily hesitant to discuss opioid use or try to wean patients off for fear of leaving them in pain. Rather, Dossett feels that the bigger issue is probably one of focus rather than fear. "Cancer providers are mostly focused on monitoring for cancer recurrence or long-term sequelae of cancer treatments," she said. "They may not recognize persistent opioid use if they are not specifically asking about it or may view persistent opioid use as falling outside their scope of practice."

David Hui, MD, associate professor in the Department of Palliative, Rehabilitation and Integrative Medicine at the University of Texas MD Anderson Cancer Center in Houston, pointed out that the study cohort was made up entirely of patients who were treated at the VA. "The VA population is unique, and may differ from the general population," he said. "The authors may want to consider validation in other settings to see if these risk factors are similar to those in VA patients."

Hui also noted that "everyone also looks at different metrics." For example, there may be patients who have been using opioids for a long period of time, but some studies may exclude that population.

But overall, even in cancer patients there is a risk of opioid misuse, which this study demonstrates, he added. "We need to tailor treatment recommendations and monitor individuals, and more research and more high quality data are needed."

Fumiko Chino, MD, a radiation oncologist at Memorial Sloan Kettering Cancer Center in New York City, "applauded the study authors in doing this important work in both highlighting opioid abuse risk factors and putting together a tool which may identify those at highest risk, ideally before they are prescribed new opioid medications."

"Obviously, all cancer doctors want to manage their patient's acute pain and symptoms for the optimal oncological and functional outcome," Chino continued. "Even for those patients at highest risk for abuse or persistent use, they may still require new or escalated opioid pain management during the course of their cancer treatment. I think what is unique about this tool is that it allows providers to understand the potential long-term risks of our treatments and factor this into their current management."

Clinically, this could mean any number of additional resources or safety checks that can be utilized early to support patients, and it also should allow for determining who may most benefit from enhanced monitoring (eg, pill counts) or altered prescribing patterns (eg, split or limited prescriptions).

Chino emphasized that there "is an important balance to be struck with opioid prescriptions for those with cancer. Nobody wants to think that we're curing cancer only to leave our former patients addicted to pain medications."

Clinicians also need to be doing better about rehabilitating patients back into a "normal life" after cancer treatment and of optimizing function and personal outcomes, she explained. For example, a portion of former patients will require chronic pain medications in the long term, and appropriate use of these long-term opioids may allow them to return to a high level of function.

"Some of my own patients worry that if they face more restrictions on their medications that they will not be able to work as they do now or complete their normal daily activities," Chino said. "They know there is a problem with opioid use in America today, but they also know that, for them, it's the right medication. It's not 'one size fits all' treatment, and each patient needs to have a pain management plan that is appropriate for their unique situation. This tool can help providers develop these plans, and for that I am grateful."

The study was supported by an ASCO Conquer Cancer Foundation Young Investigator Award. Study coauthor Murphy receives compensation for consulting from Boston Consulting Group. Study coauthor Paul Riviere receives salary support from Peptide Logic, LLC. Vitzthum, Hui, Dossett, and Chino have disclosed no relevant financial relationships.

J Natl Cancer Inst. Published online November 22, 2019. Abstract

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