Hypofractionated Radiotherapy for Prostate Cancer: The New ASTRO/ASCO/AUA Guideline

Moderately hypofractionated radiotherapy involves radiation doses of 240-340 cGy per fraction and ultrahypofractionated involves at least 500 cGy.¹

Moderate hypofractionation should be offered to patients with localized prostate cancer who are candidates for EBRT, they wrote — regardless of patient age, comorbidities, or urinary function.¹ But clinicians should discuss with patients the limited high-quality clinical trial evidence base for prostate cancer control beyond 5 years, particularly for moderate hypofractionation.

Based on high-quality evidence, moderate hypofractionation (240-340 cGy per fraction) should be recommended to patients in all risk groups, the guideline states.¹ Based on a moderate-quality evidence base, the guideline authors conditionally recommended hypofractionated regimens of 6000 cGy delivered in 20 fractions of 300 cGy and 7000 cGy delivered in 28 fractions of 250 cGy for men with localized prostate cancer, explaining that a single optimal regimen cannot yet be identified with the limited available data from clinical trials. These 2 regimens are supported by the available evidence. 

A single optimal regimen cannot yet be determined because few fractionated regimens have been evaluated in head to head clinical trials, the authors noted.¹

The guideline recommendations for ultrahypofractionation varied by risk group. The ASTRO/ASCO/AUA guideline conditionally recommended against ultrahypofractionated radiation therapy for patients with high-risk prostate cancer. Based on a moderate-quality evidence base, the guideline states that ultrahypofractionated radiation therapy may be offered to patients with low- or intermediate-risk prostate cancer but “strongly encourages treatment of intermediate-risk patients on a clinical trial or multi-institutional registry.”¹ For any hypofractionated EBRT, the task force strongly recommended the use of image-guided radiation therapy and recommended against the use of radiation-unmodulated 3-dimensional conformal radiotherapy techniques.¹

The panel suggested ultrahypofractionation schedules of 3500 cGy delivered in 5 fractions of 700 cGy or 3625 cGy in 5 fractions of 725 cGy.^1,2 Consecutive (ie, day-after-day) fractions should not be planned, however. 

The panelists reviewed 61 studies published between December 2001 and March 2017.^1,2 The studies reviewed included 4 large randomized clinical trials.^1,2

References

1. Morgan SC, Hoffman K, Loblaw DA, et al. Hypofractionated radiation therapy for localized prostate cancer: an ASTRO, ASCO, and AUA Evidence-Based Guideline. J Clin Oncol. 2018;36(34):3411-3430.

2. New ASTRO/ASCO/AUA guideline for early-stage prostate cancer supports use of shortened courses of radiation therapy [news release]. Arlington, VA; Alexandria, VA; Chicago, IL: American Society for Radiation Oncology (ASTRO), American Society of Clinical Oncology (ASCO), American Urological Association; October 11, 2018. https://www.astro.org/News-and-Publications/News-and-Media-Center/News-Releases/2018/New-ASTRO-ASCO-AUA-guideline-for-early-stage-prost. Accessed February 15, 2019.