The effect of transurethral resection on prognosis in carcinoma of the prostate: real or imaginary?

From January 1970 to June 1983, a total of 702 patients received radical external beam radiation therapy for carcinoma of the prostate. The estimated 5- to 10-year disease-free survival are 67% and 52%. A comparison was made between those patients whose diagnosis was established by needle biopsy as compared with those who had a positive transurethral resection of the prostate (TURP). Within Stages B & C combined, the 5-year disease-free survival was 65% for needle biopsy as compared with 59% for TURP. The corresponding figures at 10 years are 50% and 43%. This difference is significant with a p-value of less than 0.01. In addition to histological grade, identifiable prognostic factors in the literature are clinical stage, serum acid phosphatase, and extent of radiation (local only or prophylactic pelvic nodal radiation). Assessment of histological grade using the Gleason method has been carried out in all except 7 cases. The amount of tissue from a needle biopsy constitutes less than 3% of the material obtained from a TURP. As a result, there is a potential sampling error. The Gleason grading can be used in at least three ways: (a) the conventional Gleason score, (b) the most malignant grade identified, or, (c) the primary (most frequent) grade identified. Analyzing use of these three methods of histological stratification yields conflicting results. The difference between the needle and TURP groups is present in late stage disease when the primary grade is used for stratification but absent when the worst grade is used. The significance of these results remains more or less constant irrespective of end point (uncorrected, disease specific or disease-free survival). However, when stratified by Gleason score, it is significant for disease specific survival, approaches significance for uncorrected survival but not for disease free survival. Since the significance can be altered by changing one stratification factor, there must be some doubt about the validity of other studies which either confirm or refute the hypothesis that TURP has an adverse influence on the disease process.