Exploring the Use of Ultra-Hypofractionated RT in Elderly Breast Cancer

CancerNetwork® spoke with Bin Gui, MD, a fourth-year radiation oncology resident at the Northwell Health Cancer Institute, about the background for conducting a study to assess ultra-hypofractionated radiation in older patients with low-risk early-stage breast cancer recently presented at the 2024 American Society of Radiation Oncology (ASTRO) Annual Meeting.¹

Gui explained that ultra-hypofractionated radiation was reported to have mitigated local recurrence in 2 clinical trials, the phase 3 FAST-Forward trial (ISRCTN19906132), and an accelerated partial breast irradiation (APBI) trial (NCT02104895).^2,3 However, a third trial, the phase 3 PRIME II trial (ISRCTN95889329), disaggregated older patients with breast cancer into 2 groups; 1 cohort received radiation, and another was not assigned to radiation.⁴ He concluded by explaining that the trial he presented was to better assess whether similar efficacy would be observed for older patients as they had in the FAST-Forward and APBI trials.

The phase 3 FAST-Forward trial randomly assigned patients 1:1:1 to receive either 40 Gy in 15 fractions over 3 weeks, 27 Gy in 5 fractions over 1 week, or 26 Gy in 5 fractions over 1 week. Results from the trial found that the hazard ratio (HR) vs 40 Gy in 15 fractions was 0.67 (95% CI, 0.38-1.16) with 26 Gy in 5 fractions across 1 week.

Additionally, the APBI trial randomly assigned patients with early-stage breast cancer 1:1 to receive either whole-breast irradiation (WBI) or APBI. Results found relatively insignificant differences between WBI and APBI for outcomes like ipsilateral breast tumor recurrence (IBTR) rate (2.5% vs 3.7%).

The phase 3 PRIME II trial randomly assigned patients over 65 years with early-stage breast cancer 1:1 to receive whole-breast irradiation or no irradiation. Results from the trial showed that cumulative breast cancer recurrence was significantly higher in the no radiation group than the radiation group (9.5% vs 0.9%). However, the overall survival rate at 10 years was 80.8% and 80.7%, respectively, indicating that radiation omission did not have a significant detriment on long-term survival.

Transcript:

The ultra-hypofractionated radiation—which means [approximately] a week of radiation treatments, generally in 5 fractions—has been shown to be effective in controlling local recurrence in [patients] with early-stage breast cancer per the phase 3 FAST-Forward trial and the accelerated partial breast irradiation [APBI] trials. However, its role in the subset of older [patients[ was not specifically reported, and as we know from the phase 3 PRIME II study, it offers an option for older [patients] to omit the radiation. However, many older [patients] have diminished compliance with endocrine therapy, which was crucial in the PRIME II study.

[Our] study aimed to investigate the initial outcomes of ultra-hypofractionated radiation in older patients with low-risk breast cancer who were potential candidates for omission of radiation.

References

1. Gui B, Ojo O, Ottensoser L, et al. Ultra-Hypofractionated Radiation in Older Patients with Low Risk Early-Stage Breast Cancer. Presented at the 2024 American Society for Radiation Oncology (ASTRO) Annual Meeting; September 29 – October 2, 2024; Washington, DC. Poster 2683
2. Brunt AM, Haviland JS, Wheatley DA, et al. One versus three weeks hypofractionated whole breast radiotherapy for early breast cancer treatment: the FAST-Forward phase III RCT. Health Technol Assess. 2023;27(25). doi:10.3310/WWBF1044
3. Meattini I, Marrazzo L, Saieva C, et al. Accelerated partial-breast irradiation compared with whole-breast irradiation for early breast cancer: long-term results of the randomized phase III APBI-IMRT-Florence trial. J Clin Oncol. 2020;38(35):4175-4183. doi:10.1200/JCO.20.00650.
4. Kunkler IH, Williams LJ, Jack WJL, et al. Breast-conserving surgery with or without irradiation in early breast cancer. N Engl J Med. 2023;388(7):585-594. Doi:10.1056/NEJMoa2207586