What question did this study set out to answer?

To assess breast toxicities and the influence of dosimetric parameters in patients receiving ultra-hypofractionated radiotherapy for breast cancer.

June 14, 2026Open Access

Optimizing outcomes with less than more: multi-institutional experience of fast-forward fractionation and the impact of dosimetric parameters on toxicity in breast cancer patients

Key Points

To assess breast toxicities and the influence of dosimetric parameters in patients receiving ultra-hypofractionated radiotherapy for breast cancer.
Retrospective study of 100 breast cancer patients receiving 26 Gy in 5 fractions of radiotherapy from June 2020 to June 2023.
Collected breast toxicity data via medical chart reviews and verbal reports from patients lost to follow-up.
Examined correlations between dosimetric factors, body mass index (BMI), and toxicity symptoms.
Out of 85 analyzed patients, breast skin dermatitis occurred in 82.35% (n=70), with 5% experiencing Grade III toxicity.
Breast pain rated ≥5 on the pain scale was reported in 15% of cases, significantly correlated with larger breast volume and higher V107% values (p=0.013, p=0.012).
Dermatitis significantly correlated with breast CTV, BMI, and breast separation (p=0.0001, p=0.015, p=0.001).

Abstract

Background The FAST-Forward trial demonstrated the non-inferiority of 26 Gy in five fractions compared to 40 Gy in 15 fractions over five years. This study aimed to report observed breast toxicities and examine the impact of dosimetric parameters in ultra-hypofractionated radiotherapy (RT) across a diverse patient population in Saudi Arabia. Methods This multi-institutional retrospective study evaluated 100 breast cancer patients treated with whole-breast adjuvant radiotherapy (26 Gy in 5 fractions) between June 2020 and June 2023, with adjuvant RT at two different institutions in Saudi Arabia. Breast toxicity data were retrospectively collected from medical chart review and verbal reports from patients lost to follow-up. Correlations between dosimetric factors, body mass index (BMI), and acute and late toxicity symptoms were statistically assessed. Results A total of 85 patients were included in the analysis after excluding those with incomplete toxicity data with a median follow-up of 19 months. Breast skin dermatitis was the most common side effect (82.35%, n=70) with 5% of patients experiencing Grade III, followed by hyperpigmentation (72.9%, n=62), breast discomfort (30.3%, n=26) and breast hardness (17.6%, n=15). Breast pain rated ≥5 out of 10 on the pain scale was reported in 15% of cases. Breast pain had a significant correlation with larger breast volume and higher V107% values (p=0.013, and p=0.012 respectively). Furthermore, breast skin dermatitis was significantly correlated with breast CTV, BMI, and breast separation (p=0.0001, 0.015, and 0.001 respectively). Conclusions Ultra-hypofractionated RT with a 26 Gy in five fractions schedule was well tolerated in our patient cohort. A larger breast volume, higher BMI, and increased V105% and V107% were associated with greater toxicity. Optimizing modifiable dosimetric factors may reduce adverse effects. Consequently, these findings offer valuable insights into treatment refinement.

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