Prostate cancer clinical trial completion: The role of geography

One in five cancer clinical trials fails with another third failing to meet enrollment goals. Prior efforts to improve enrollment focus on patient facing interventions, but geographic factors such as regional cancer incidence may doom trials before they even begin. For these reasons, we examined associations of regional prostate cancer incidence with trial termination, and identified scientifically-underserved areas where future trials might thrive.

We merged US phase 2-3 prostate cancer clinical trial data from ClinicalTrials.gov with prostate cancer incidence data from statecancerprofiles.cancer.gov. We matched trial information from 293 closed and 560 active trials with incidence data for 2947 counties. Using multivariable logistic regression, we identified associations with trial termination. We identified 'scientifically-underserved' counties with the highest cancer incidence quintile (>61 annual cases) but lowest active trials quintile (0 or 1 trial).

Of 293 closed trials, one in three was terminated (n = 96, 32.8%). On multivariable analysis, only lower regional prostate cancer incidence was associated with higher likelihood of premature trial termination (OR 0.98, 95% CI [0.96-0.99] for every 100 cases, p = 0.03). We identified 188 counties with >61 annual prostate cancer cases but 0 or 1 active trials, indicating potential scientifically-underserved areas.

In this novel study, we found prostate cancer trials in areas with low prostate cancer incidence were more likely to fail. We also identified scientifically-underserved areas where trials might thrive. Our findings provide a more nuanced understanding of clinical trial feasibility and upstream opportunities for improvement.