Chronic pain is a risk factor for all-cause and cancer-specific mortality in cancer survivors: a population-based cohort study.

Background: Evidence is lacking on whether chronic pain is related to the risk of cancer mortality. This study seeks to unveil the association between chronic pain and all-cause, cancer, as well as non-cancer death in cancer patients based on the National Health and Nutrition Examination Survey (NHANES) database.

Methods: Cancer survivors aged at least 20 (n = 1369) from 3 NHANES (1999-2004) cycles were encompassed. Chronic pain and cancer were determined through self-report. We employed records from the National Death Index for the determination of death status and reason. All-cause, cancer, and non-cancer deaths were primary outcomes. We used time-dependent ROC curve assessment to evaluate the predictive value of chronic pain for death in cancer patients.

Results: Over a median 141-month follow-up (interquartile range: 61-201 months), 884 (64.57%) of 1,369 cancer sufferers died, of which 259 (18.91%) died from cancer, and 625 (45.65%) from other causes. Compared with non-chronic pain survivors, chronic pain correlated with elevated all-cause mortality (Hazard Ratio (HR), 1.40; 95% CI, 1.14-1.72, p = 0.001) and cancer death (HR, 1.75; 95% CI, 1.16-2.64, p = 0.008), primarily in patients with pain lasting 3 months or more. Chronic pain was related to higher non-cancer mortality (HR, 1.38; 95% CI, 1.04-1.82, p = 0.025), and no significant results were found in pain duration. Time-dependent ROC curves showed the area under the curve (AUC) for all-cause mortality at 1, 3, 5, 10, and 20-year survival for chronic pain of 0.71, 0.78, 0.84, 0.89, and 0.96, respectively. The AUCs for cancer mortality at 1, 3, 5, 10, and 20-year for chronic pain were 0.83, 0.87, 0.91, 0.94, and 0.95, respectively, and those for non-cancer mortality at 1, 3, 5, 10, and 20-year for chronic pain were 0.82, 0.86, 0.90, 0.91, and 0.97, respectively.

Conclusion: Chronic pain is associated with heightened all-cause and cancer mortality in the cancer population. Clinical staff should focus on chronic pain in this patient population.