POSSIBLE MECHANISM FOR SEEDING OF TUMOR DURING RADICAL PROSTATECTOMY

Prostatic adenocarcinoma sometimes recurs locally in the operative bed after radical prostatectomy. Having observed local recurrence in seve ral patients who had a small tumor confined to the prostate on whole m ount serial sections, we postulated that some instances of local recur rence could arise from malignant cells shed in prostatic secretions ex pressed during surgery. To evaluate whether prostatic secretions conta in malignant cells and to estimate the frequency of this phenomenon, w e collected fresh prostatic secretions from radical prostatectomy spec imens immediately after removal. The secretions were analyzed by cytol ogy for the presence of malignant cells. Of 76 samples collected from consecutive patients with clinical stages Tl and T2 prostate cancer at 3 institutions 11 (14%) contained malignant cells. Positive cytology results were most frequent in patients with poorly differentiated tumo rs. Of 11 cancers with a Gleason sum of 8 to 10 in the prostatectomy s pecimen 6 (55%) had a positive cytology result. However, of 63 tumors with a Gleason sum of 5 to 7 only 4 (6%) were positive (p <0.0001). Th ere was no significant correlation with either clinical or pathologica l stage of the tumor in this small series. Our findings suggest that m alignant cells shed during prostatectomy may seed the surgical bed and could be responsible for some instances of local tumor recurrence. Th e rate of positive cytology results in our study is similar to the loc al recurrence rates reported in the literature. Surgeons should make p rudent attempts to avoid seeding from this source.