Hypofractionated intensity-modulated radiotherapy in patients with localized prostate cancer: a preliminary study

Abstract

Purpose: The aim of this work was to assess the efficacy and tolerability of hypofractionated intensity-modulated radiotherapy (IMRT) in patients with localized prostate cancer.

Materials and methods: Thirty-nine patients who received radical hypofractionated IMRT were retrospectively reviewed. Based on a pelvic lymph node involvement risk of 15% as the cutoff value, we decided whether to deliver treatment prostate and seminal vesicle only radiotherapy (PORT) or whole pelvis radiotherapy (WPRT). Sixteen patients (41%) received PORT with prostate receiving 45 Gy in 4.5 Gy per fraction in 2 weeks and the other 23 patients (59%) received WPRT with the prostate receiving 72 Gy in 2.4 Gy per fraction in 6 weeks. The median equivalent dose in 2 Gy fractions to the prostate was 79.9 Gy based on the assumption that the α/β ratio is 1.5 Gy.

Results: The median follow-up time was 38 months (range, 4 to 101 months). The 3-year biochemical failure-free survival rate was 88.2%. The 3-year clinical failure-free and overall survival rates were 94.5% and 96.3%, respectively. The rates of grade 2 acute genitourinary (GU) and gastrointestinal (GI) toxicities were 20.5% and 12.8%, respectively. None of the patients experienced grade ≥3 acute GU and GI toxicities. The grade 2-3 late GU and GI toxicities were found in 8.1% and 5.4% of patients, respectively. No fatal late toxicity was observed.

Conclusion: Favorable biochemical control with low rates of toxicity was observed after hypofractionated IMRT, suggesting that our radiotherapy schedule can be an effective treatment option in the treatment of localized prostate cancer.

Keywords: Disease-free survival; Intensity-modulated radiotherapy; Prostate cancer; Toxicity.

Fig. 1. Dose distribution on transverse and coronal slices of (A) PORT and (B) WPRT. Planning was carried out as described in the Materials and Methods section. (A) PORT plan shows planning target volume (PTV) coverage by 45-Gy and 40-Gy isodose lines. (B) WPRT plan shows PTV coverage by 72-Gy, 66-Gy, and 54-Gy isodose lines. PORT, prostate and seminal vesicle only radiotherapy; WPRT, whole pelvis radiotherapy.

Fig. 2. Kaplan-Meier estimates of disease-free survival. BFFS, biochemical failure-free survival; CFFS, clinical failure-free survival; OS, overall survival.