Characteristics and risk differences of different tumor size on localized prostate cancer: A retrospective cohort study in the SEER database.

Objective: We aimed to evaluate the role of tumor size in predicting tumor risk for localized prostate cancer (PCa) patients undergoing radical prostatectomy (RP).

Methods: Twenty-five thousand, one hundred twenty-seven men with PCa receiving RP from 2010 to 2015 were extracted from the Surveillance, Epidemiology, and End Results database. Kaplan-Meier plots and multivariable Cox regression analyses were used to illustrate overall survival (OS) according to the tumor size. The tumor size was confirmed by postoperative pathology after RP.

Results: Among overall localized PCa, 84.6% were high-risk PCa, 9.2% were intermediate-risk PCa, and 6.2% were low-risk PCa. Multivariate analyses demonstrated that tumor size ≥21 mm was an independent risk predict factor of low-risk PCa (odds ratio [OR]: 11.940; 95% CI, 9.404-15.161; p < 0.001) and intermediate-risk PCa (OR: 1.887; 95% CI, 1.586-2.245; p < 0.001). Tumor sizes ≤5 mm significantly correlated with high-risk PCa (p < 0.001). Tumor size ≤5 mm had the worst OS in overall localized PCa and high-risk PCa (p < 0.001).

Conclusions: In localized PCa, tumor sizes ≥21 mm may help predict low or intermediate-risk PCa, while tumor sizes ≤5 mm might help predict high-risk PCa. In clinical practice, we should be on high alert for patients with tumors size ≤5 mm due to its poor prognosis after RP.