Stage T1c prostate cancer: A heterogeneous category with widely varying prognosis

PURPOSE: Stage T1c prostate cancer is defined as nonpalpable disease diagnosed by needle biopsy. As more patients are being diagnosed early because of prostate-specific antigen (PSA) screening, the distribution of patients by stage has shifted dramatically. Although this group has traditionally been characterized as having early-stage disease and the best prognosis, on review of these patients, we instead found a very heterogeneous group with a wide spectrum of outcomes that depend on both patient (Gleason grade and pretreatment PSA) and treatment (dose) factors. METHODS AND MATERIALS: A retrospective analysis was performed on 353 patients with stage T1c prostate adenocarcinoma who were referred for radiation therapy from 1989-1999. All patients underwent central review of pathology. Patients were treated with external-beam radiation to doses of 60-78 Gy; 66% of the patients were treated with a dose of 70 Gy or higher. Clinical local recurrence, nodal recurrence, distant metastases, and PSA relapse were recorded. Kaplan-Meier methodology was used to determine survival. For evaluation of prognostic variables, the patients were grouped by Gleason score (2-6, 7, 8-10), pretreatment PSA level (< 10, 10-20, > 20 ng/mL), and dose delivered to the prostate (≤ 70 Gy, > 70 Gy). The log-rank test was used for univariate analysis, and Cox-regression was used for multivariate analysis. RESULTS: The median age was 69 years, and the median follow-up of surviving patients was 47 months. As a percentage of all patients with prostate cancer, stage T1c continually increased from 6% in 1989 to 47% in 1999. Of the 353 patients with T1c, 66% of the patients were in the Gleason group of 2-6, 27% had a Gleason score of 7, and 7% had a Gleason score of 8-10. Sixty-five percent of the group had a pretreatment PSA level of < 10 ng/ mL, 31% had a PSA level of 10-20 ng/mL, and 5% had a PSA level of > 20 ng/mL. For the entire group, the 8-year overall survival was 86%, and PSA relapse-free survival was 78%. By univariate analysis, Gleason score and pretreatment PSA were significant predictors of overall survival and PSA relapse-free survival. For PSA relapse-free survival, a radiation dose of more than 70 Gy was also a significant factor. By multivariate analysis, Gleason score, pretreatment PSA level, and radiation dose over 70 Gy were significant predictors of PSA relapse-free survival. As expected, patients with Gleason score ≤ 6 and pretreatment PSA < 10 had an 8-year RFS of 90%, whereas patients with Gleason score of 8-9 and pretreatment PSA > 20 had a relapse-free survival of zero percent. DISCUSSION: Contrary to general assumption, stage T1c prostate cancer is composed of a very heterogeneous group of patients with varying outcomes. When treatment modalities and institutional data are evaluated, the spectrum of disease must be accounted for by additional prognostic factors and subset analysis. Improvement in prostate imaging and multiple core biopsies may be helpful in better defining the extent of disease in the individual patient.