Opioids may influence breast cancer survival

A new study in the April issue of Anesthesiology analyzed inherited (genetic) differences in how the body responds to its own morphine-like chemicals and pain-relieving opioid drugs, and whether they influence breast cancer survival. Preclinical animal studies have suggested that opioids may promote tumor growth.

"Many are unaware that the human body produces its own morphine-like chemicals every day," said senior study author Samuel McLean, M.D. "Therefore, if morphine-like chemicals influence cancer survival, then naturally occurring inherited differences in how the body responds to its own morphine-like chemicals and pain-relieving opioid drugs also should be associated with cancer survival."

More than 2,000 women with breast cancer were included in the study. The authors assessed six naturally occurring genetic variations which might influence the body's response to morphine-like chemicals. In particular, the well-known A118G variation in the mu-opioid receptor gene was assessed. Genotyping was performed to examine the association between these variations and breast cancer survival.

Findings showed that the patient genotype A118G was associated with breast cancer-specific mortality at 10 years. Women with one or more copies of the G variant had decreased breast cancer-specific mortality. The results suggest that opioid pathways may be involved in tumor growth. Further studies are needed to examine how genetic variants influencing opioid system function may relate to cancer survival.

"Our hope is that other researchers can perform studies similar to ours, with their own patient data, to see if they obtain similar results," said study co-investigator Andrey Bortsov, M.D., Ph.D. "If so, then this would increase the likelihood that this is a true finding. If opioid systems influence tumor growth, then this could open up new opportunities for treating cancer using relatively non-toxic treatments."

Source: American Society of Anesthesiologists