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Top Line: Is there a difference in local recurrence between hypofractionation and conventional fractionation for high risk breast cancer subtypes?

The Study: Recently, a large study from the Michigan Radiation Oncology Quality Consortium (MROQC) showed that there was no difference in recurrence risk between moderate hypofractionation (HF) and conventional fractionation (CF) for early stage, triple negative breast cancer. Here’s another large study that compares outcomes based on fractionation among 300 women with a wider variety of T1-2 N0 “high risk” breast cancer. Eligible patients had triple negative breast cancer (41%), HER2+ breast cancer (41%), or hormone receptor positive breast cancer with a 21-gene recurrence score >25. Most (57%) were treated with CF to a total dose of 45-50.4 Gy with 99% of those receiving a lumpectomy boost of 10-20 Gy. Those treated with HF (43%) received a total of 40-42.56 Gy with 80% receiving a lumpectomy boost of 7.5-16 Gy. The cohort spanned a 20 year period from 1999 to 2019, so there were several significant differences in underlying patient and treatment characteristics according to fractionation. After accounting for these differences, there were no discernable differences in disease or survival outcomes. At 5 years, the rate of local recurrence was 1.6% with HF v 2.9% with CF.

TBL: There is no difference in the rate of recurrence when moderate hypofractionation is used for women with high risk, early stage breast cancer. | Willen, Pract Radiat Oncol 2022