Moderate hypofractionated helical tomotherapy for older patients with localized prostate cancer: Long-term outcomes of a phase I-II trial

Abstract

Background. Previous study showed that two different regimens of moderate hypofractionated radiotherapy (HFRT) delivered with helical tomotherapy (HT) are well tolerated in older prostate cancer patients. We provide a long-term efficacy and toxicity after >7 years of follow-up.

Patients and methods. This study recruited 33 patients from February 2009 to July 2011 (76Gy/34F; Group 1), 34 from July 2011 to February 2014 (71.6Gy/28F; 50.4Gy/25F for the risk of pelvic lymph nodes involvement (LNI) >15%; Group 2). The primary outcomes were biochemical failure (BF), biochemical failure and clinical disease failure (BCDF), progression-free survival (PFS), overall survival (OS), late genitourinary (GU) and gastrointestinal (GI) toxicity.

Results. The median age for two groups were 80 and 78 years, with 69.7% and 73.5% LNI >15%, respectively. At last follow-up: 27.3% and 20.6% cases experienced BF, with a median time until BF of 3.3 years. A total of 38.8% patients reached primary endpoints, in which 18 deaths were reported BCDF events (45.5% vs 32.4%, p=0.271). There were no significant difference in 7-year PFS (68.6% vs 74.8%, p=0.591), BCDF (45.5% vs 32.4%, p=0.271) and OS (71.9% vs 87.5%, p=0.376) for full set analysis and for subgroup analysis (all p>0.05). The grade ≥ 2 late GU (6.2% vs 6.3%, p=0.127) and GI toxicities (9.4%vs 15.6%, p=0.554) was comparable.

Conclusions. In older patients with localized prostate cancer, two moderate hypofractionated regimens were all well tolerated with similar, mild late toxicities and satisfactory survival, without necessity of prophylactic pelvic node irradiation.