Shorter radiotherapy regimens as good as conventional one in breast cancer

The ten-year results of the FAST trial have found that a once-weekly 5-fraction schedule of whole-breast radiotherapy appeared to be radiobiologically comparable to a conventionally fractionated regimen. The trial was published in the journal, "Journal of Clinical Oncology" 2020.

15- or 16-fraction (fr) regimen was considered standard for early breast cancer for hypofractionated adjuvant whole-breast radiotherapy. The main objective of the FAST trial was to test the reduction in a total dose of adjuvant whole-breast radiotherapy delivered by 5 once-weekly fractions. They evaluated normal tissue effects (NTE) and disease outcomes after 5-fr regimens and presented the ten-year results.

Professor Murray Brunt, Professor of Clinical Oncology at the University Hospitals of North Midlands and the University of Keele, who is joint first author of the study, said: "The FAST trial identifies a five-fraction once-a-week regimen that is equivalent to daily treatment over the same period. The follow-up to 10 years is important in establishing the principle of a five-treatment option".

"For patients unable to attend daily this offers an alternative much more convenient once-a-week treatment option that is attractive to both patients and their carers."

For the study, the researchers randomly assigned women ≥ 50 years of age with low-risk invasive breast carcinoma (pT1-2 pN0) to 50 Gy/25 fr for 5 weeks or, 30 or 28.5 Gy in 5 once-weekly fr of 6.0 or 5.7 Gy. The primary endpoint of measurement was to check the change in photographic breast appearance at 2 and 5 years. The secondary endpoints were physician assessments of NTE and local tumor control. Odds ratios (ORs) from longitudinal analyses compared regimens.

The key findings of the study were:

• A total of 915 women were recruited from 18 UK centers (2004-2007).

• Five-year photographs were available for 615/862 (71%) eligible patients.

• ORs for change in photographic breast appearance was 1.64 (P = .019) for 30 Gy and 1.10 (P = .686) for 28.5 Gy versus 50 Gy.

• α/β estimate for photographic endpoint was 2.7 Gy, giving a 5-fr schedule of 28 Gy estimated to be isoeffective with 50 Gy/25 fr.

• ORs for any moderate/marked physician-assessed breast NTE (shrinkage, induration, telangiectasia, edema) were 2.12 (P < .001) for 30 Gy and 1.22 (P = .248) for 28.5 Gy versus 50 Gy.

• With 9.9 years median follow-up, 11 ipsilateral breast cancer events 3 for 50 Gy, 4 for 30 Gy, and 4 for 28.5gy.

• There were 96 deaths of 30 in 50Gy, 33 in 30 Gy, and 33 in 28.5Gy have occurred. 

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