Changes in use of opioid therapy after colon cancer diagnosis: a population-based study.

Purpose: To describe patterns of opioid use in cancer survivors.

Methods: In a cohort study of colon cancer patients diagnosed during 1995-2014 and enrolled at two Kaiser Permanente regions, we constructed quarterly measures of opioid use from 1 year before cancer diagnosis through 5 years after diagnosis to examine changes in use. Measures included any use, incident use, regular use (use ≥ 45 days in a 91-day quarter), and average daily dose (converted to morphine milligram equivalent, MME). We also assessed temporal trends of opioid use.

Results: Of 2,039 colon cancer patients, 11-15% received opioids in the four pre-diagnosis quarters, 68% in the first quarter after diagnosis, and 15-17% in each subsequent 19 quarters. Regular opioid use increased from 3 to 5% pre-diagnosis to 5-7% post diagnosis. Average dose increased from 15 to 17 MME/day pre-diagnosis to 14-22 MME/day post diagnosis (excluding the quarter in which cancer was diagnosed). Among post-diagnosis opioid users, 73-95% were on a low dose (< 20 MME/day). Over years, regular use of opioids increased in survivorship with no change in dosage.

Conclusion: Opioid use slightly increased following a colon cancer diagnosis, but high-dose use was rare. Research is needed to differentiate under- versus over-treatment of cancer pain.