Carbon ion radiotherapy for prostate cancer

Therapeutic outcome of hypofractionated conformal carbon ion radiotherapy towards localized prostate cancer was investigated. We analyzed the biochemical relapse-free rate of 1,084 cases which were observed for 6 months or more after carbon ion radiotherapy at the time of February 2011, also we analyzed survival rate, and the incidence of toxicity. 5-year biochemical relapse-free rate of whole cases was 90.6%. The Gleason score, prostate specific antigen (PSA) value and clinical stage were the significant prognostic factor of relapse-free rate. The difference of relapse-free rate by method of fractionation (20 fractions and 16 fractions) was not found. None but one out of 1,005 cases who were followed up at least 1 year developed grade 3 lower urological impairment, and incidences of grade 2 were 5.6% in lower urinary tract and 2.3% in the rectum, respectively. Furthermore, in the 16 fractions, the toxicity incidence was lower than 20 fractions. Accordingly, hypofractionation made it possible to reduce the toxicity incidence without reducing the relapse-free rate. (author)