[Iodine 125 prostate brachytherapy: prognostic factors for long-term urinary, digestive and sexual toxicities]

For patients with good urinary function and presenting with a low risk prostate cancer, prostate brachytherapy using iodine implants represents one of the techniques of reference. This retrospective analysis investigates urinary (U), digestive (D) and sexual (S) toxicities and their prognostic factors of duration.

From August 2000 to November 2007, 176 patients presenting with prostate adenocarcinoma underwent interstitial brachytherapy. Urinary, digestive and sexual toxicities were classified according to Common toxicities criteria for adverse events, version 3.0 (CTCAE V3.0). For each toxicity (U, D, S), the number of complications U (dysuria, nicturia...), D (proctitis, diarrhea...) and S (sexual dysfunction, loss of libido, ...) was listed and analyzed according to criteria related to the patient, implant, dosimetric data and characteristics of the toxicity. Prognostic factors identified in univariate analysis (UVA) (Log Rank) were further analyzed in multivariate analysis (MVA) (Cox model).

With a median follow-up of 26 months (1-87), 147 patients (83.5 %) presented urinary toxicities. Among them, 29.5 % (86 patients) and 2.4 % (seven patients) presented grade 2 and 3 U toxicity respectively. In UVA, urinary grade toxicity greater than or equal to 2 (p=0.037), the presence of initial U symptoms (p=0.027) and more than two urinary toxicities (p=0.00032) were recognized as prognostic factors. The number of U toxicities was the only prognostic factor in MVA (p=0.04). D toxicity accounted for 40.6 % (71 patients). Among them, 3 % (six patients) were grade 2. None were grade 3. Two factors were identified as prognostic factors either in UVA and MVA: the number of D toxicities greater than or equal to 2 (univariate analysis: p=0,00129, multivariate analysis: p=0,002) and age less than or equal to 65 years (univariate analysis: p=0,004, multivariate analysis: p=0,007). Eighty-three patients (47.4 %) presented a sexual toxicity; 26.9 % (49 patients) and 5 % (nine patients) were scored as grade 2 and 3 respectively. A number of seeds greater than 75 (p=0.032) and S grade greater than or equal to 2 (p<0.0001) were recognized as prognostic factors in UVA. S grade was the only prognostic factor in MVA (p=0.0015).

The duration of U, D and S toxicity is strongly correlated with a high number of toxicities and the grade of toxicity. This analysis allows for better information given to the patient regarding the duration of the post-treatment complications.