Clinical significance of cancer in radical prostatectomy specimens: analysis from a contemporary series of 2900 men

Hemamali Samaratunga, Brett Delahunt, John Yaxley, Joanna Perry-Keene, David S. Lamb, John R. Srigley, Lars Egevad, John N. Nacey

With prostate specific antigen (PSA) testing, up to 49% of detected tumours are small and in some of these cases there is a possibility that the tumour will remain clinically insignificant during the patient's remaining lifetime. The current study was performed to characterise the extent of cancer in men treated by radical prostatectomy (RP) in a community without population-based PSA screening. Clinical and pathological data of 2900 patients who underwent RP between 2008 and 2012 were analysed. Specimens were entirely embedded and evaluated by routine haematoxylin and eosin staining. Tumours were graded using recent modifications to the International Society of Urological Pathology (ISUP) modified Gleason grading system, and staged according to the ISUP recommendations. Tumours were considered pathologically insignificant if organ confined, with a volume of <0.5  cc and a Gleason score (GS) of <7. The mean age of patients in the series was 63 years (range 32-79 years) and the mean pre-operative PSA was 7.16  ng/mL (range 0.4-69). In total, 2614 (90.1%) were classified as cT1; however, insignificant tumours were found in only 150 (5.2%) patients following examination of the radical prostatectomy specimen. A total of 2681 cases (92.4%) had a final GS of ≥7, 1144 (39.4%) had extraprostatic extension (EPE), of which 88.7% were classified as established; 669 (23.1%) had a tumour volume of >3  cc and 284 (9.8%) had surgical margin positivity. Seminal vesicle involvement was seen in 159 (5.5%) cases. Of 693 patients who had a lymphadenectomy, 31 (4.5%) had lymph node metastases. Aged ≤50 years were 212 (7.3%) patients (mean age 47 years). Of these, 194 were classified as cT1 while 192 (90.6%) were found to have significant cancer on examination of the radical prostatectomy specimen. We have shown in our series that although 90.1% of tumours were cT1, an overwhelming majority of tumours were found to be pathologically significant following RP, with a high proportion of cases showing high stage disease, seminal vesicle involvement and lymph node metastasis. These results suggest that, contrary to estimates from international trials, ad hoc PSA testing is associated with low levels of over-treating.