Radioterapia adyuvante en el cáncer de mama: análisis comparativo de la toxicidad de 2 esquemas de hipofraccionamiento

Objective

Adjuvant radiotherapy (RT) for breast cancer has been given in 1.8–2 Gy daily fractions for decades. Protracted schemes have proven as effective and safe as conventional. Schemes involving 5 fractions once a week are as safe as those involving one daily fraction for three weeks. We compared acute and late toxicity of two hypofractionated regimes.

Material and methods

Retrospective single-center observational study involving 100 unselected patients, treated with adjuvant radiotherapy for breast cancer with either 40 Gy/15 fr/3 weeks or 28,5 Gy/5 fr/5 weeks (1:1 ratio). Statistical tests used: Mann–Whitney U and Chi-square (χ²). Toxicity (assessed by physicians/nurses using RTOG/CTCAE Score at end of treatment, one month and six months later) was retrieved from patients notes.

Results

Median follow-up: 16.6 months. Average age: 59 years. The comparison between the 15-session and 5-session groups revealed the following results: boost: 24% vs. 2%; lumpectomy: 62% vs. 92%; mastectomy 38% vs. 14%; lymphadenectomy 36% vs. 14%; RT to SCF + level III: 54% vs. 8%; acute skin toxicity 70% vs. 60%; acute odynophagia: 16% vs. 2%; late toxicity (induration, edema, deformity-distortion, telangiectasias, hyperpigmentation) 30% vs. 52%.

Conclusion

Odynophagia was more frequent in weekly treatments. Prophylactic nodal irradiation rates could be a confounding factor. A modest excess of G1 breast induration in 5 fractions schemes was detected. To summarize, both schemes are similar concerning acute and late toxicity.