Reducing radiation-associated toxicity using online image guidance (IGRT) in prostate cancer patients undergoing dose-escalated radiation therapy.

AIM

To determine the influence of IGRT in terms of toxicities compared to non-IGRT patients undergoing definitive RT.

BACKGROUND

Image-guided radiotherapy (IGRT) enables immediate correction of target movement by online imaging. For prostate cancer patients undergoing radiation therapy (RT), a geographical miss of the prostate may result in increased dose-volume effects in the rectum and bladder.

METHODS

A total of 198 prostate cancer patients treated between 2003 and 2013 were recruited randomly for this evaluation. The rates of genitourinary (GU) and gastrointestinal (GI) toxicity for 96 non-IGRT patients (total dose: 72/73.8 Gy) were compared to those for 102 IGRT patients (total dose: 77.4 Gy) according to the Common Toxicity Criteria Version 3.0 (CTCAEv3.0). Follow-up information included treatment-related symptoms and PSA relapse.

RESULTS

After a median follow-up of 55.4 months, a statistically significant difference was noted for acute GI toxicities ≥1 in favour of IGRT. Significantly more patients treated by IGRT were free of acute GI symptoms (43% vs. 19%, p = 0.0012). In the non-IGRT group, more patients experienced acute GU side effects (89% vs. 80%, p = 0.07). Late toxicity scores were comparable for both cohorts.

CONCLUSIONS

Based on the data, we demonstrated that despite dose escalation, IGRT enabled us to reduce the GI side effects of radiation. IGRT can therefore be considered to be the standard of care for dose-escalated RT of localized prostate cancer.