Predictors for progression of metastatic prostate cancer to castration-resistant prostate cancer in Indians

BACKGROUND & OBJECTIVES: There is lack of data on natural history and progression of prostate cancer (PC) which have implications in the management of the disease. We undertook this retrospective study to analyze factors predicting progression of metastatic PC to castration-resistant prostate cancer (CRPC) in Indian men. METHODS: Complete records of 223 of the 489 patients with metastatic PC were obtained from computerized data based system in a tertiary care hospital in north India between January 2000 to June 2012. Patients with follow up of < 6 months were excluded. Age (≤ and > 65 yr), baseline PSA (< and ≥ 50 ng/ml), bone scan and Gleason score (≤7 and >7) were recorded. Extent of bone disease (EOD) was stratified according to the number of bone lesions i.e., < 5, 5-10, > 10. CRPC was defined as two consecutive PSA rise of > 50 per cent from nadir or an absolute value of > 5 ng/ml. RESULTS: Mean age of patients was 61.5 ± 12.45 yr and their PSA level was 325.6 ± 631.35 ng/dl. Of the 223 patients, 193 (86%) progressed to CRPC at median time of 10.7 (4-124) months. Median follow up was 24 (6-137) months. On univariate and multivariate analyses EOD on bone scan was found to be a significant predictor (P=0.006) for time to CRPC. Median time to CRPC was 10 months (CI 95%, 7.5-12.48) with >10 lesions or super scan versus 16 months (CI 95%, 10.3-21.6) with <10 bone lesion (P=0.01). Ninety (46.6 %) patients of CRPC died with median time to death from time of CRPC 21 (10-120) months. INTERPRETATION & CONCLUSIONS: Median time for progression of metastatic PC to CRPC ranged from 10-16 months depending on the extent of the bone involvement. In Indians, the aggressive course of advanced prostate cancer warrants further clinical trials to explore the need for additional treatment along with initial castration.