Nov. 22 (UPI) -- Pain is an unfortunate reality for most people with various forms of cancer. Now, a new study suggests its management may produce even more challenging complications.
In an analysis of medical records for more than 100,000 adults with cancer, published Friday in the Journal of the National Cancer Institute, researchers from the University of California-San Diego found that nearly 3 percent of these patients were diagnosed with opioid abuse or dependence after completing cancer treatment. More than 2 percent were admitted to the hospital due to opioid-related health problems, including overdoses.
"Opioids play an important role in helping patients with pain from cancer, or pain because of treatment," study co-author James D. Murphy, a radiation oncologist at UCSD, said in a statement. "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."
According to UCSD, pain is one of the most difficult symptoms associated with cancer. More than half of cancer patients undergoing treatment experience moderate to severe pain.
Despite the accepted role of opioids in acute pain relief, however, the use of opioids for chronic pain -- or pain lasting longer three to six months -- remains controversial, Murphy and his colleagues noted. Chronic opioid use has been linked with the diminishing effectiveness of the drugs, as well as dependence, misuse, abuse and unintentional overdosing.
With an estimated 16.9 million cancer survivors in the United States, and two-thirds of newly diagnosed cancer patients living more than five years, the need to better understand the role of opioid use in this population is critical, Murphy and his colleagues wrote.
To that end, they reviewed the medical records 106,732 cancer survivors from a Veterans' Administration database who were diagnosed with cancer between 2000 and 2015, tracking rates of persistent post-treatment opioid use, diagnoses of opioid abuse or dependence, and admissions for opioid toxicity.
Patients included in the analysis were diagnosed with one of the 12 most common cancers -- bladder, breast, colon, esophagus, stomach, head and neck, kidney, liver, lung, pancreas, prostate, or rectal cancer -- and survived for a minimum of two years, without recurrence, after treatment.
The overall incidence of persistent post-treatment opioid use was 8.3 percent, which varied by cancer type ranging from a low of 5.3 percent in prostate cancer patients to a high of 19.8 percent in liver cancer patients. Bladder, breast, esophagus, stomach, head and neck, liver, lung and pancreas cancer were also associated with higher rates of persistent opioid use compared to prostate cancer.
In addition, rates of persistent opioid use after treatment varied substantially by a patient's history of opioid use prior to his receiving a cancer diagnosis.
The persistent post-treatment opioid use rates were lowest for patients who had never used opioids prior to their cancer diagnosis, at 3.5 percent, followed by prior intermittent users, at 15.0 percent, and prior chronic users, at 72.2 percent.
Several factors were associated with the risk of persistent opioid use, the authors found. Younger age, white race, unemployment at the time of cancer diagnosis, lower median income, increased comorbidity, and current or prior tobacco use were all associated with increased risk for persistent opioid use. Also, prior diagnoses of alcohol abuse, non-opioid drug abuse, opioid abuse and depression were associated with increased odds, as were prior history of chronic opioid use and intermittent use.
"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," said Lucas K. Vitzthum, resident in the department of radiation medicine at UCSD. "Ultimately, clinical tools such as ours could help providers identify which patients could benefit from alternative pain management strategies or referral to pain specialists."