Second malignancies after permanent implant prostate cancer brachytherapy: A single-institution study of 675 patients treated between 1999 and 2003

To analyse the rate of secondary malignancies observed in a series of 675 prostate cancer patients who underwent a permanent implant brachytherapy between 1999 and 2003, and to compare the incidence with the expected rate in a matched general French population. The cohort included low-risk patients and a selection of “favourable-intermediate” risk patients. All patients were homogeneously treated using an intraoperative dynamic planning prostate brachytherapy technique, with loose 125-iodine seeds and a prescription dose of 145Gy. The mean follow-up was 132 months. The 10-year overall survival for the entire cohort was 92% (95% confidence interval [CI]: 90–94). The 10-year relapse-free survival rate was 82% (95% CI: 79–85). Overall, 61 second cancers were registered. When comparing with a matched general French population, the standard incidence ratio (SIR) for bladder cancer was 1.02 (95% CI: 0.46–1.93). For colorectal cancer, the SIR was 0.45 (95% CI: 0.19–0.89). For lung cancer, the SIR was 0.38 (95% CI: 0.17–0.76). The SIR for all cancers was 0.61 (95% CI: 0.47–0.79). When excluding secondary colorectal and lung cancers (both with low SIRs in this series), the SIR for all cancers was 1.06 (95% CI: 0.77–1.29). With a mean follow-up of more than 11 years, this series does not detect any excess risk of second cancers associated with permanent implant prostate brachytherapy. However, due to power limitation, a small increase in the risk of secondary malignancies cannot be totally ruled out. Analyser les cancers secondaires observés dans une série de 675 patients pris en charge par une curiethérapie de prostate par implants permanents entre 1999 et 2003, et comparer leur incidence à celle attendue dans une population générale correspondante en France. La cohorte étudiée a inclus des patients à bas risque et une sélection de patients de risque intermédiaire « favorable ». Tous ont été pris en charge de manière homogène par une curiethérapie prostatique par grains libres d’iode 125, utilisant une technique en temps réel. La dose prescrite était de 145Gy. Le suivi moyen est de 132 mois. La probabilité de survie globale à 10 ans était de 92 % (intervalle de confiance [IC] à 95 % : 90–94). La survie sans récidive à 10 ans est de 82 % (IC 95 % : 79–85). Soixante-et-un cancers secondaires ont été observés. La comparaison avec une population française de mêmes structure d’âge et sexe a montré un rapport d’incidence (standard incidence ratio [SIR]) pour le cancer de