Improved Outcomes for Prostate Cancer Using Hypofractionated Radiotherapy and Dose Escalation to 55Gy

Abstract Introduction: This Centre has previously reported outcomes for patients treated with neoadjuvant hormone therapy (NAHT) and 52.5Gy in 20 fractions. We now present the outcome data for patients treated with 55Gy in 20 fractions and NAHT. Methods and Materials: 584 patients were treated for T1-T3 node negative prostate cancer. The median age was 67.2 years (range 49-80). All patients received 3 months of NAHT followed by CT planned conformal radiotherapy to the prostate using 55Gy in 20 fractions. 147 patients considered at particularly high risk of relapse also received 2 years of adjuvant androgen deprivation. Outcomes were obtained through serial PSA measurement. Patients were classified into prognostic groups according to Zelefsky criteria. PSA relapse was defined according to Houston criteria. The outcomes with 55Gy were compared with the 52.5Gy cohort. Results: The 10 year cause specific survival increased from 67.3% with 52.5Gy to 92.9% in the 55Gy group. Patients receiving 55Gy had better outcomes than those receiving 52.5Gy in all prognostic groups with or without adjuvant hormone use. PSA relapse free survival at five years in the patients who did not receive adjuvant hormones are:- 80.2 v 63.6% in the ‘Good’, 69.5 v 43.7% in the ‘Intermediate’ and 40.3 v 15.3% in the ‘Poor’ prognostic groups (p<0.01). Conclusions: Our results demonstrate improved outcomes with prostate radiotherapy across all prognostic groups with a modest dose escalation from 52.5 to 55Gy in 20 fractions. This supports evidence of a steep dose response gradient and a low alpha beta ratio in this cancer.