Radical prostatectomy for impalpable prostate cancer: The Johns Hopkins experience with tumors found on transurethral resection (stages T1A and T1B) and on needle biopsy (stage T1C)

We review the pathological findings of impalpable prostate cancer detected by transurethral resection (stages T1a and T1b) and needle biopsy (stage T1c). The short-term (4 years) and long-term (8 to 10 years) natural histories of untreated stage T1a prostate cancer are examined, as are options to follow patients expectantly. The findings on radical prostatectomy for stages T1a and T1b disease are reviewed and compared. Of the 64 cases of stage T1a disease 13 (20%) showed substantial tumor, including 7 with more than 1 cc of tumor, 5 with capsular penetration and 1 with a Gleason grade 4 + 5 = 9 tumor. Based on preoperative pathological parameters, one could not predict which cases had minimal versus substantial tumor. In a study from our institution that undertook complete histological examination of 39 radical prostatectomy specimens of stage T1b carcinoma, we found that all prostates contained residual carcinoma, 26% had capsular penetration and 10% had invasion of the seminal vesicles. When comparing morphometrically determined volumes of carcinoma with similar data from 56 patients with stage T2 carcinoma, stage T1b tumors were much more heterogenous in grade, location and volume than were stage T2 lesions. Unless all 3 variables (grade, volume and location) were known, the final pathological stage of T1b cancers could not be predicted with confidence. Finally, we examined preoperative clinical and pathological parameters in 157 men with clinical stage T1c disease undergoing radical prostatectomy, and correlated these findings with pathological extent of disease in the surgical specimen in an attempt to identify a subset of patients with potentially biologically insignificant tumor who might be followed conservatively. Of the tumors 16% were insignificant (less than 0.2 cc, organ confined and Gleason grade less than 7), 10% were minimal (0.2 to 0.5 cc, organ confined and Gleason grade less than 7), 37% were moderate (more than 0.5 cc or capsular penetration with Gleason sum less than 7) and 37% were advanced (capsular penetration with Gleason sum 7 or more, or positive margins, positive seminal vesicles or positive lymph nodes). These findings are intermediate between those found in clinical stages T1a and T2 disease. The best model predicting insignificant tumor was a prostate specific antigen (PSA) density of less than 0.1 and no adverse pathological finding on needle biopsy or a PSA density of 0.1 to 0.15 with less than 3 mm. low to intermediate grade cancer on only 1 needle biopsy core. The positive predictive value of the model was 95% with a negative predictive value of 66%. Using this model, we accurately predicted 73% of cases with insignificant tumor. Although most impalpable prostate cancers diagnosed by needle biopsy are significant tumors that warrant definitive therapy, it may be reasonable to follow some patients whose tumors are most likely insignificant with serial PSA measurements and repeat biopsies.