Randomized trial comparing conventional-dose with high-dose conformal radiation therapy in early-stage adenocarcinoma of the prostate: long-term results from proton radiation oncology group/american college of radiology 95-09

Abstract

PURPOSE To test the hypothesis that increasing radiation dose delivered to men with early-stage prostate cancer improves clinical outcomes. PATIENTS AND METHODS Men with T1b-T2b prostate cancer and prostate-specific antigen </= 15 ng/mL were randomly assigned to a total dose of either 70.2 Gray equivalents (GyE; conventional) or 79.2 GyE (high). No patient received androgen suppression therapy with radiation. Local failure (LF), biochemical failure (BF), and overall survival (OS) were outcomes. Results A total of 393 men were randomly assigned, and median follow-up was 8.9 years. Men receiving high-dose radiation therapy were significantly less likely to have LF, with a hazard ratio of 0.57. The 10-year American Society for Therapeutic Radiology and Oncology BF rates were 32.4% for conventional-dose and 16.7% for high-dose radiation therapy (P < .0001). This difference held when only those with low-risk disease (n = 227; 58% of total) were examined: 28.2% for conventional and 7.1% for high dose (P < .0001). There was a strong trend in the same direction for the intermediate-risk patients (n = 144; 37% of total; 42.1% v 30.4%, P = .06). Eleven percent of patients subsequently required androgen deprivation for recurrence after conventional dose compared with 6% after high dose (P = .047). There remains no difference in OS rates between the treatment arms (78.4% v 83.4%; P = .41). Two percent of patients in both arms experienced late grade >/= 3 genitourinary toxicity, and 1% of patients in the high-dose arm experienced late grade >/= 3 GI toxicity. CONCLUSION This randomized controlled trial shows superior long-term cancer control for men with localized prostate cancer receiving high-dose versus conventional-dose radiation. This was achieved without an increase in grade >/= 3 late urinary or rectal morbidity.

Fig 1.

CONSORT diagram. GyE, Gray equivalents.

Fig 2.

Biochemical failure after either conventional-dose or high-dose conformal radiation therapy. (A) Biochemical failure by American Society for Therapeutic Radiology and Oncology consensus. (B) Biochemical failure by Phoenix criteria. GyE, Gray equivalents.

Fig 3.

Biochemical failure by American Society for Therapeutic Radiology and Oncology Consensus definition after either conventional-dose or high-dose conformal radiation therapy. (A) Biochemical failure for the low-risk group; (B) biochemical failure for the intermediate-risk group. GyE, Gray equivalents.