Predictors of cancer progression in T1a prostate adenocarcinoma

BACKGROUND The biologic behavior of T1a prostate adenocarcinoma is variable. A critical issue in the management of patients with T1a prostate adenocarcinoma is to distinguish those who will develop cancer progression from those who will not. Predictive factors that identify those at high risk of cancer progression are needed to stratify patients for treatment. In the current study the authors attempted to identify such predictors of cancer progression in a large series of untreated patients with lengthy follow‐up. METHODS The authors studied 102 patients who were diagnosed with T1a prostate adenocarcinoma (incidental tumor involving ≤ 5% of the resected prostatic tissue) at the time they underwent transurethral resection of the prostate (TURP) at the Mayo Clinic between 1960–1970. None of these patients were treated. Patient ages ranged from 48–91 years (mean ± standard deviation, 69 ± 7 years). The average weight of the resected prostate tissue was 24 ±18 g (range, 3–115 g; median, 18 g). Tumor volume was measured by the grid method. Cox proportional hazards models were used to identify factors associated with cancer progression. Survival curves were estimated using the Kaplan‐Meier method. RESULTS Five‐year and 10‐year progression free survival rates were 93% and 87%, respectively. During the mean follow‐up of 9.5 ± 6.8 years (range, 0.3–31 years; median, 9.0 years), 14 patients developed clinical cancer progression, including 5 patients with systemic progression (1 with distant metastases and 4 who died of prostate adenocarcinoma). The interval from diagnosis to clinical cancer progression ranged from 1–23 years (mean, 7.3 years). The amount of resected prostate tissue (TURP weight) was associated with progression (P = 0.04). Patients with a TURP weight ≥ 30 g had 100% progression free survival at 10 years compared with a progression free survival rate of 73% in patients with a TURP weight < 12 g. Gleason score, tumor volume, number of chips involved by tumor, number of tumor foci, and the presence of high grade prostatic intraepithelial neoplasia were not significant in predicting cancer progression. There was a trend toward a worse prognosis with the increasing number of chips involved by cancer (P = 0.16). Patients with < 3 chips involved by cancer had a 88% 10‐year progression free survival rate compared with 73% in patients with ≥ 3 chips involved by cancer. CONCLUSIONS The clinical course of T1a prostate adenocarcinoma is variable. If left untreat