Image-guided dose-escalated radiation therapy for localized prostate cancer with helical tomotherapy.

Abstract

To evaluate treatment outcomes for patients with localized prostate cancer who were treated with dose-escalated primary image-guided radiation therapy (IGRT). We retrospectively analyzed 88 consecutive patients treated using helical tomotherapy with daily megavoltage CTs (MVCT). Patients were prescribed daily doses of 1.8 Gy to the planning target volume (PTV) and 2 Gy to the clinical target volume (CTV). Low- and favorable intermediate-risk patients received aminimum total dose of 72 Gy to the PTV and up to 80 Gy to the CTV. Unfavorable intermediate-risk and high-risk patients received aminimum total dose of 75.6 Gy to the PTV and up to 84 Gy to the CTV. We assessed freedom from biochemical relapse (FFBF), 5‑year biochemical recurrence-free survival (5-bRFS), distant metastasis-free survival (5-dMFS), and cancer-specific survival (5-CSS) as well as acute and late genitourinary (GU) and gastrointestinal (GI) toxicity. Among our cohort, 11.4% were low-risk, 50% intermediate-risk, and 38.6% high-risk patients according to the D'Amico criteria. Median follow-up was 66months (range8-83months). FFBF was 100%, 97.7%, and 90.7%; 5‑bRFS was 100%, 92.8%, and 70.4%; 5‑dMFS was 100%, 92.7%, and 70.4%; and 5‑CSS was 100%, 97.4%, and 89.8% for low-, intermediate-, and high-risk patients, respectively. Grades2 and3 toxicity occurred at the following rates: acute GU toxicity 39.8% and 1.1%, acute GI toxicity 12.5% and 0%, late GU toxicity 19.3% and 4.5%, and late GI toxicity 4.5% and 1.1% of patients, respectively. No toxicity >grade3 was observed. Risk-adapted dose-escalated IGRT with helical tomotherapy of up to 84 Gy is afeasible and well-tolerable treatment scheme with promising oncological results.