By Dr. Hiba Siddiqui
Abstract:
Introduction:
Breast cancer has a relatively low α/β ratio, estimated around
3–4 Gy. This suggests a heightened sensitivity to larger fraction
sizes, thereby providing a strong radiobiological rationale for
hypo-fractionation. The objective of this study is to evaluate
whether a hypo-fractionated regimen of 43.5 Gy in 15 fractions
(2.9 Gy/Fr) is clinically and dosimetrically equivalent to the
conventional regimen of 50 Gy in 25 fractions, based on the α⁄
β ratio of 4 Gy.
Methodology:
This is a retrospective study including locally advanced breast
cancer patients treated between 2022 and 2025 at our
institution. Inclusion criteria were age > 18 years, who had
undergone mastectomy and had primary breast carcinoma
stage T2–4 or N1-N2 disease. Patients with incomplete
treatment records or follow-up data were excluded from the
analysis.
Results:
A total of 45 locally advanced breast cancer patients were
included in the analysis. The mean age was 55.5 years. The
majority had stage II-B disease (55.5%), followed by stage III
(44.4%). The 3D CRT technique was used in 30 patients
(65.2%). The mean heart dose was 6.0 Gy. The ipsilateral mean
lung dose was 13.6 Gy, and the ipsilateral lung V20 was 27.6%.
After radiation, 26 patients (56.5%) developed grade 2
dermatitis. No cases of radiation pneumonitis were observed at
the 6-week follow-up.
Conclusion:
The use of the post-mastectomy radiotherapy regimen of 43.5
Gy in 15 fractions was well tolerated, with acceptable toxicity
and dosimetric parameters. These findings suggest that
exclusive hypofractionation may serve as a safe and effective
alternative to conventional fractionation in post-mastectomy
breast cancer patients, particularly in settings where treatment
efficiency and resource optimization are essential.