Effect of prior cancer on trial eligibility and treatment outcomes in nasopharyngeal carcinoma: Implications for clinical trial accrual.

Objective: In cancer trials, prior cancer is a common exclusion criterion. We evaluated the characteristics of prior cancer exclusion criteria in nasopharyngeal carcinoma (NPC) trials and determined its prognostic effect on patients with NPC.

Methods: We reviewed NPC trials for prior cancer exclusion criteria. Then we estimated the effect of prior cancer among NPC patients using the Surveillance, Epidemiology, and End Results database.Propensity score-matching was used to compensate for differences in baseline characteristics between patients with and without prior cancer.

Results: There were 109 clinical trials involving 10,437 patients; 49 trials (45%) excluded patients with prior cancer. Prior cancer exclusion was more common in recent or phase III trials. We identified 10,195 NPC patients; 6.2% had prior cancer. More than 70% of these cancers were in situ/localized/regional and diagnosed relatively close to the NPC diagnosis (median 3.3 years). Patients with certain prior cancer type (prostate, breast, gynecological, hematological), time of diagnosis (>5 years ago), or stage (in situ/localized) did not have inferior survival compared with patients with no prior cancer. We tested one form of prior cancer exclusion criteria in an NPC cohort resembling a modern trial population: it did not adversely affect overall and NPC-specific survival.

Conclusions: Many NPC trials excluded patients with prior cancer, whichimpacts trialaccrual and generalizability. Our findings suggest that broader inclusion in trials of patients with NPC with prior cancer might not affect trial outcomes. More research is needed to understand the appropriateness of this exclusion policy across cancer types and trials.