Accuracy of frozen section detection of lymph node metastases in prostatic carcinoma.

To examine the accuracy of frozen sections in the detection of pelvic lymph node metastases in patients with prostatic cancer, the results of frozen and paraffin sections were compared in 75 consecutive patients with clinical stage A or B prostatic cancer. Frozen sections were positive for cancer in 16 patients (21 per cent), 14 of whom had gross lymphadenopathy, and in all cases cancer was confirmed on paraffin sections. Of 59 patients with negative frozen sections 11 (19 per cent) had paraffin sections positive for cancer. However, in 10 of these 11 patients there were only 1 or 2 microscopic metastases. Thirteen other patients with normal-appearing lymph nodes did not have frozen sections obtained at the time of operation and metastases were not found on paraffin sections. There was a direct correlation between tumor grade and nodal involvement. The results suggest that frozen sections are of limited reliability in identifying lymph node metastases in patients who do not have gross lymphadenopathy. The extent to which this inaccuracy may result in the selection of inappropriate therapy remains to be determined.