Image-guided radiation therapy based on helical tomotherapy in prostate cancer: minimizing toxicity.

BACKGROUND: We report the clinical results and prognostic factors of image-guided radiation therapy (RT) with helical tomotherapy (HT) for localized and recurrent prostate cancer (PC). PATIENTS AND METHODS: We evaluated 70 patients with PC (primary diagnosis, n = 48; adjuvant, n = 5; salvage, n = 17) treated with HT from May 2006 through January 2011. The dose prescribed to the prostate/surgical bed ranged between 60 and 78 Gy. Potential risk factors for genitourinary (GU) and gastrointestinal (GI) toxicity were assessed. RESULTS: The median age was 68 years (range 51-87 years). The median follow-up was 37 months (range 3-74 months). The rates of acute grade 2 GI and GU toxicities were 10 and 13%, respectively. Only 1 patient experienced acute grade 3 GU toxicity. The rates of late grade ≥ 2 GI and GU toxicities were 1% each. Multivariate analysis showed an association between rectum mean dose > median (39 Gy) and bladder median dose > median (46 Gy) with a higher grade of acute GI (p = 0.017) and GU (p = 0.019) toxicity, respectively. Additionally, older age was associated with late GU toxicity (p = 0.026). CONCLUSION: Toxicity with HT is low and is associated with higher median/mean doses in organs at risk as well as with older age. A prospective validation would be necessary to confirm these results.