Outcomes, Toxicities, and Dosimetric Comparison of Different Hypo-fractionated Intensity Modulated Radiotherapy Techniques for Treatment of Localized Prostate Cancer

Background: Conventional fractionation IMRT is the standard treatment for localized prostate cancer patients. The objectives of this study were to evaluate the safety and efficacy of hypo-fractionated radiotherapy with a dosimetric comparison between 5, 7, and 9 IMRT fields.
Methods: Low or intermediate-risk patients included. Three sets of Inverse planning IMRT were carried out (5, 7, and 9- Fields) for each patient with a total dose of 70 Gy/ 28 fractions.
Results: 20 patients were recruited. Regarding PTV coverage, there were no statistically significant differences regarding D2%, D5%, D50%, D95%, D98%, Dmax, Dmin, Dmean, conformity index, or homogeneity index, between 5, 7, or 9-Fields. (p= 0.25, 0.38, 0.969, 0.057, 0.294, 0.057, 0.517, 0.969, 0.313 and 0.969, respectively). The statistically significant difference regarding longer treatment time (p= 0.039) and more monitor units (p= 0.015) between 5 and 9-fields with no significant difference between 7 and 9-fields. The mean doses of V25%, V35%, and V50% of the rectum were significantly higher for the 5-fields compared to the 7 and 9-fields (p=0.001, 0.001, 0.006). The 2-year biochemical control rate was 95% and the DFS was 100%. Acute gastrointestinal toxicities G1 55%, G2 40%, and G3 5% while late toxicities G1 25% and G2 15%. Acute genitourinary toxicities G 1 60%, G2 35%, and G3 5%, and for late toxicities G1 30% and G2 10%. No late G3 nor G4 toxicities were observed.
Conclusion: Hypo-fractionated radiotherapy is safe and effective regarding the biochemical control and toxicity profile, more convenient, and less costly.