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 several patients who had a small tumor confined to the prostate on whole mount serial sections, we postulated that some instances of local recurrence could arise from malignant cells shed in prostatic secretions expressed during surgery. To evaluate whether prostatic secretions contain malignant cells and to estimate the frequency of this phenomenon, we collected fresh prostatic secretions from radical prostatectomy specimens immediately after removal. The secretions were analyzed by cytology for the presence of malignant cells. Of 76 samples collected from consecutive patients with clinical stages T1 and T2 prostate cancer at 3 institutions 11 (14%) contained malignant cells. Positive cytology results were most frequent in patients with poorly differentiated tumors. Of 11 cancers with a Gleason sum of 8 to 10 in the prostatectomy specimen 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). There was no significant correlation with either clinical or pathological stage of the tumor in this small series. Our findings suggest that malignant cells shed during prostatectomy may seed the surgical bed and could be responsible for some instances of local tumor recurrence. The rate of positive cytology results in our study is similar to the local recurrence rates reported in the literature. Surgeons should make prudent attempts to avoid seeding from this source.