Objective: This paper describes the first-year biochemical (prostate-specific antigen [PSA]) response of 91 irradiated patients enrolled in a single-institution randomized trial comparing hypofractionated (HFRT) and conventionally fractionated (CFRT) external beam radiotherapy.
Material and methods: Forty-four patients in the CFRT treatment arm were irradiated with 74 Gy in 37 fractions (2 Gy per fraction), and 47 in the HFRT arm were treated with 57 Gy, given in 13 fractions of 3 Gy plus 4 fractions of 4.5 Gy. The clinical target volume includes the prostate and a base of seminal vesicles. The proportions of patients who reached PSA nadir (nPSA) lower than or equal to 1.0 ng/mL (nPSA1) and 0.5 ng/mL (nPSA05) were compared.
Results: There were 2 non-cancer-related deaths (1 in the CFRT and 1 in the HFRT treatment arms). Biochemical relapse after irradiation was defined in five cases (3 in the CFRT and 2 in the HFRT treatment arms) during a 12-month follow-up. The remaining 84 patients were analyzed. The proportions of patients reaching nPSA1 were 50% and 54.5% in the CFRT and HFRT treatment arms, respectively (chi-square P=0.843). The percentages of patients reaching nPSA05 were 25% and 18.2%, respectively (chi-square P=0.621). The trends toward increasing proportions of biochemical responders (both nPSA1 and nPSA05) during 12 months after radiotherapy were observed, but the difference between trends for treatment arms did not reach a statistical significance.
Conclusion: The preliminary results presented here demonstrate that HFRT schedule induces biochemical response rates comparable to those in the CFRT schedule during the first-year follow-up.