Medivation Inc.'s strong Phase III survival data for prostate cancer drug MDV-3100 raise two questions. First, can the prostate cancer market support so many players? And second, with the bar for survival edging higher, is there a place for Phase III prostate cancer trials with alternate endpoints, like Exelixis Inc.'s pain-focused study of cabozantinib?Analysts say yes on both counts.While many prostate cancer drugs are starting to come onto the market, they are largely targeting different stages of the disease.