New York, Apr 22 (IANS): Many cancer patients use marijuana and its usage has increased, a new study suggests. The findings, published in the journal CANCER, indicate 40.3 per cent cancer patients used marijuana within the past year, compared with 38 per cent of respondents without cancer.

"Prospective clinical trials are needed to quantify the efficacy of marijuana in cancer-specific pain as well as the risk of opioid misuse in this patient population," said co-author Kathryn Ries Tringale from the University of California, San Diego.

For the study, 826 people with cancer were matched to 1,652 controls.

The researchers found significantly increased use of marijuana over time -- likely reflecting increased availability due to legislative changes -- but they found stable rates of opioid use.

They found patients with cancer were more likely to use prescription opioids than adults without cancer -- 13.9 per cent versus 6.4 per cent.

"Medical marijuana legislation has previously been associated with reduction in hospitalisations related to opioid dependence or abuse, suggesting if patients are in fact substituting marijuana for opioid, this may introduce an opportunity for reducing opioid-related morbidity and mortality," said lead author Jona Hattangadi-Gluth from the varsity.