Definition of Insignificant Tumor Volume of Gleason Score 3 + 3 = 6 (Grade Group 1) Prostate Cancer at Radical Prostatectomy-Is it Time to Increase the Threshold?

Only 3.8% of less than 0.5 cm3 Gleason score 3 + 3 = 6 (Grade Group 1) cancers had extraprostatic extension or extended apically where surgical removal was not possible. In contrast, 11.1% of 0.5 to 2.0 cm3 cancers had these adverse features and would not have been tumors amenable to active surveillance. Our data indicate that increasing the threshold above 0.5 cm3 is associated with a significantly increased likelihood of extraprostatic extension and positive surgical margins. This should be considered in future studies of the prognostic value of tumor volume and in studies of active surveillance criteria.