The immunohistochemical assessment of occult regional lymph node metastases in patients with T3pN0M0 prostate cancer before definitive radiotherapy

Objective To detect occult regional lymph node metastases in patients with T3pN0M0 prostate cancer not recognized by routine haematoxylin and eosin st aining, and to evaluate the clinical relevance of this finding. Patients and methods Formalin-fixed and paraffin-embedded pelvic lymph node s (1118) from 92 patients were evaluated by immunohistochemistry using anti bodies for prostate specific antigen (PSA) and pancytokeratin (AE1/AE3). Of the tumours, 14% were well, 69% moderately and 17% poorly differentiated. The extent of tumour was categorized as T3pN0M0 in all patients, who were r eferred for definitive radiotherapy after pelvic staging lymphadenectomy. T he median (range) serum PSA value before treatment was 18.5 (0.4-342) mu g/ L. After radiotherapy, the patients were followed by assessing biochemical progression, pelvic recurrence and/or development of distant metastases. Th e median (range) observation time for all patients was 61 (16-136) months, Results Occult lymph node metastases were detected in four (4.4%) of the 92 patients, Patients with or without occult metastases had similar serum PSA levels and histological grades, None of the four patients with occult meta stases progressed, compared with 37 of the 88 (42%) with no such metastases . Conclusion Using immunohistochemistry the detection rate of occult lymph no de metastases in patients with T3pN0M0 prostate cancer is low, The occurren ce of such metastases is probably unrelated to the serum PSA value before t reatment, The short-term outcome of patients subsequently treated with defi nitive radiotherapy does not seem to be associated with the finding of occu lt lymph node metastases, but longterm follow-up is needed, So far, the res ults do not justify the search for occult lymph node metastases as a routin e procedure in these patients.