Carbon ion radiotherapy for prostate cancer

Analysis on the results of hypofractionated conformal carbon ion radiotherapy (C-ion RT) for localized prostate cancer was performed, with regard to normal tissue morbidity, biochemical relapse-free rate (bNED), and patient survival. Eight hundreds and eighteen prostate cancer patients who received C-ion RT established through two preceded dose-escalation studies were analyzed in regard to toxicity, survival, and bNED. Concerning radiation morbidity, no grade 3 or higher toxicities were observed either in the rectum or genitourinary system (GU), and the incidences of grade 2 rectum and GU morbidity were only 1.9% and 5.8%, respectively. Incidence of late toxicity in the patients treated with C-ion RT of 16 fractions was lower than that of 20 fractions. Overall bNED at 5 years was 90.1%, with only five local recurrences. The bNED of the C-ion RT of 16 fractions was comparable to that of 20 fractions. Gleason's score, T-stage, and initial PSA were significant prognostic factors for bNED, and T-stage and initial PSA were also significant prognostic factors for overall survival rate. C-ion RT with the established dose fractionation regimen yielded satisfactory bNED with very few local recurrences, and with minimal morbidity. C-ion RT of 16 fractions could offer even lower incidence of GU toxicity than that of 20 fractions, without deteriorating the biochemical control. (author)