Influence of the technique and comorbidities in hypofractionated radiotherapy for prostate cancer

To analyze the differences in toxicity and biochemical relapse-free survival with hypofractionated radiotherapy with three-dimensional radiotherapy (3D-CRT) or volumetric arc therapy (VMAT) for prostate cancer taking into account comorbidity measured using the Charlson Comorbidity Index (CCI).

From January 2011 to June 2016, 451 patients with prostate cancer were treated with 60 Gy (20 daily fractions). VMAT or 3D-CRT was used. Distribution by stage: 17% low-risk, 27.2% intermediate-risk; 39.2% high-risk, 16.6% very high-risk. Mean CCI was 3.4.

With a median follow up of 51 months, most patients did not experience any degree of acute GI toxicity (80.9%) compared to 19.1%, who experienced some degree, mainly G-I /II. In the multivariate analysis, only technique was associated with acute GI toxicity ≥ G2. Patients treated with VMAT had greater acute GI toxicity compared with those who received 3D-CRT (23.9% vs. 13.5%, p = 0.005). With respect to acute GU toxicity, 72.7% of patients experienced some degree, fundamentally G-I/II. Neither age, CCI, nor androgen deprivation therapy (ADT) were associated with greater toxicity. Overall survival at 2, 5 and 7 years was 97%, 88% and 83% respectively. The only factor with statistical significance was CCI, with a greater number of events in individuals with a CCI ≥ 4 (p < 0.03).

Hypofractionated radiotherapy for prostate cancer is an effective, well-tolerated treatment even for elderly patients with no associated comorbidity. Longer follow up is needed in order to report data on late toxicity.