Conditional survival in pancreatic cancer: better than expected

Traditional survival estimates after resection for pancreatic cancer are based on clinicopathological variables at the time of diagnosis. Estimates have not reflected time survived after resection, as investigated for other malignancies. The aim of the present study was to understand how survival estimates change after pancreatic resection for cancer based on time already survived (conditional survival).

Pancreatectomies performed for pancreatic ductal adenocarcinoma (PDAC) between 2001 and 2010 were reviewed. Clinicopathological variables were evaluated to identify predictors of survival. Expected survival according to a validated nomogram for pancreatic cancer as well as conditional survival estimates and actual survival were calculated.

In all, 186 patients underwent pancreatic resection for PDAC [154 (82.8%) Whipple, 26 (14.0%) distal and 6 (3.2%) total]. Median (range) survival was 22 (3.4-107.3) months. Predictors of overall survival were: absence of nodal disease [odds ratio (OR) 8.8], age <67 years (OR 8.4) and lower stage (OR 4.3). Expected survival according to the nomogram was 70% (1 year), 39.5% (2 years) and 24% (3 years). As time passed, and overall and expected survival decreased, conditional survival increased.

The available prognostic system for PDAC underestimated survival compared with actual survival in the present study. Conditional survival estimates, based on accrued lifespan, were better than either predicted or actual survival, suggesting that survival is a dynamic, rather than static, concept. Conditional survival may, therefore, be a useful tool to allow patients and clinicians to project subsequent survival based on time accrued since resection.