A prostate cancer stage defined by the Jewett staging system. Stage C prostate cancer is cancer that began in the prostate, has grown beyond the outer layer of the prostate to nearby tissues, and may be found in the seminal vesicles (glands that help produce semen). Stage C is divided into stages C1 and C2. In stage C1, the cancer has grown outside the prostate but has not spread to lymph nodes or other places in the body. In stage C2, the cancer has grown outside the prostate and blocks urine flow from the bladder or through the ureters.