Cellular proliferative fraction of metastatic lymph nodes predicts survival in stage D1 (TxN+MO) prostate cancer

Purpose: We assessed the ability of tumor cellular proliferative fraction to predict long-term survival among patients with lymphatic metastases from prostate cancer. Materials and Methods: We studied 50 patients with stage D1 (TxN+M0) prostate cancer who underwent pelvic lymphadenectomy and (125)iodine seed implantation between 1970 and 1978. We used the MIB-1 monoclonal antibody to Ki67 to stain sections of the lymphatic metastases in these patients. The Ki67 proliferative fraction was defined as the fraction of positively stained malignant nuclei. We also used flow cytometry to determine the deoxyribonucleic acid content of the lymphatic metastases. Results: Median followup was 6.1 years. Patients whose metastases had a Ki67 proliferative fraction of less than 0.1 had significantly longer survival compared to those with a proliferative fraction of greater than 0.1 (8.7 years versus 4.4 years, respectively, p = 0.005, log rank test). The Ki67 proliferative fraction and ploidy were not independent variables. Patients whose metastases were diploid had a significantly longer survival than those with aneuploid metastases (8.8 years versus 4.4 years, respectively, p = 0.01, log rank test). Multivariate analysis showed that ploidy had a slightly stronger effect on survival than did the Ki67 proliferative fraction. Conclusions: Cellular proliferative fraction of lymphatic metastases is useful to predict survival in patients with stage D1 prostatic carcinoma. Proliferative fraction may be useful as a marker of progression among patients with other stages of disease.