Purpose: To evaluate treatment outcomes for patients with localized prostate cancer who were treated with dose-escalated primary image-guided radiation therapy (IGRT).
Methods: 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 a minimum total dose of 72 Gy to the PTV and up to 80 Gy to the CTV. Unfavorable intermediate-risk and high-risk patients received a minimum 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.
Results: 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 66 months (range 8-83 months). 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. Grades 2 and 3 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 >grade 3 was observed.
Conclusion: Risk-adapted dose-escalated IGRT with helical tomotherapy of up to 84 Gy is a feasible and well-tolerable treatment scheme with promising oncological results.
Keywords: Dose-escalation; Image-guided radiation therapy; Primary radiation therapy; Prostate cancer; Tomotherapy.