Hypofractionated Radiation Therapy for Localized Prostate Cancer: Executive Summary of an ASTRO, ASCO and AUA Evidence-Based Guideline

Abstract

The aim of this guideline is to present recommendations regarding moderately hypofractionated (240-340 cGy per fraction) and ultrahypofractionated (500 cGy or more per fraction) radiation therapy for localized prostate cancer. Methods and Materials: The American Society for Radiation Oncology convened a task force to address 8 key questions on appropriate indications and dosefractionation for moderately and ultrahypofractionated radiation therapy, as well as technical issues, including normal tissue dose constraints, treatment volumes, and use of image guided and intensity modulated radiation therapy. Recommendations were based on a systematic literature review and created using a predefined consensus-building methodology and Society-approved tools for grading evidence quality and recommendation strength. Results: Based on high-quality evidence, strong consensus was reached for offering moderate hypofractionation across risk groups to patients choosing external beam radiation therapy. The task force conditionally recommends ultrahypofractionated radiation may be offered for low-and intermediate-risk prostate cancer but strongly encourages treatment of intermediate-risk patients on a clinical trial or multi-institutional registry. For high-risk patients, the task force conditionally recommends against routine use of ultrahypofractionated external beam radiation therapy. With any hypofractionated approach, the task force strongly recommends image guided radiation therapy and avoidance of nonmodulated 3-dimensional conformal techniques. Conclusions: Hypofractionated radiation therapy provides important potential advantages in cost and convenience for patients, and these recommendations are intended to provide guidance on moderate hypofractionation and ultrahypofractionation for localized prostate cancer. The limits in the current evidentiary basedespecially for ultrahypofractionationdhighlight the imperative to support large-scale randomized clinical trials and underscore the importance of shared decision making between clinicians and patients.

Assessing localized dosimetric effects due to unplanned gas cavities during pelvic MR‐guided radiotherapy using Monte Carlo simulations

“…Treatments with low doses per fraction could be used to reduce the overall effect of large dose hotspots in the rectal wall. Ultra‐hypofractionated treatments using large doses per fraction could be prohibited, or replanned if unplanned gas is detected during daily imaging …”

“…All simulations were prescribed 4 Gy to the isocenter, using 1% statistical uncertainty, 0.1‐cm grid spacing, and an MR‐Linac‐specific beam model. The 4‐Gy dose prescription was chosen in line with the various conventional External Beam Radiotherapy (EBRT; 1.8–2 Gy), moderately hypofractionated (2.4–3.4 Gy), and ultra‐hypofractionated (>5–7.25 Gy) prostate dose prescriptions and treatment schedules …”

Genomics models in radiotherapy: From mechanistic to machine learning

“…Hypofractionation — both moderate and stereotactic‐level — was also not addressed but has since become standard of care for several of the most commonly treated organ sites. ASTRO guidelines for hypofractionated or stereotactic treatment have published within past 2 yr for lung, prostate, and breast cancer . Since QUANTEC, there have been similar efforts by PENTEC (Pediatric Normal Tissue Effects in the Clinic) and the AAPM working group HyTEC (Hypofractionation Treatment Effects in the Clinic) to determine normal tissue effects for pediatric patients and hypofractionated regimens, respectively.…”

Quality of life after external beam radiotherapy for localized prostate cancer: Comparison with other modalities

“…Based on these large trials, as well as additional single‐institution randomized trials, hypofractionated EBRT guidelines were published collaboratively by the American Society of Clinical Oncology, the American Urological Association and the American Society for Radiation Oncology . In these guidelines, it is concluded that patients treated with moderate hypofractionation (2.4–3.4 Gy per fraction) might have a small increased risk of acute GI toxicity, and have a similar risk of acute and late GU and late GI toxicity compared with conventionally fractionated EBRT, although it should be noted that these data were based on most randomized trials with limited follow up beyond 5 years.…”

“…Clinicians should keep in mind that an increase of just 1.25 Gy in total dose has tended to increase toxicity. Therefore, in the guidelines mentioned above, although ultrahypofractionation might be offered as an alternative to conventional fractionation in men with low‐risk prostate cancer, ultrahypofractionation for patients with intermediate‐ or high‐risk prostate cancer should be used as part of a clinical trial or multi‐institutional registry due to the possible risk of late toxicity . The support of clinical trials or multi‐institutional registries is required to firmly assess the efficacy and toxicity of ultrahypofractionated EBRT.…”