Side effects of 5-day radiation for breast cancer
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Side Effects of 5-Day Radiation for Breast Cancer
Introduction to Hypofractionated Radiotherapy
Hypofractionated radiotherapy, which involves delivering higher doses of radiation over a shorter period, has gained attention for its potential benefits in treating breast cancer. Specifically, a 5-day radiation schedule has been compared to the traditional 3-week regimen to evaluate its efficacy and safety.
Efficacy and Safety of 5-Day Radiation
Local Tumor Control and Normal Tissue Effects
The FAST-Forward trial investigated the efficacy and safety of a 5-fraction schedule delivered over 1 week compared to the standard 15-fraction regimen over 3 weeks. The study found that the 5-day schedule (26 Gy in five fractions) was non-inferior to the 3-week schedule (40 Gy in 15 fractions) in terms of local tumor control, with similar 5-year incidences of ipsilateral breast tumor relapse .
Normal Tissue Effects
However, the side effects on normal tissues varied. Clinician-assessed moderate or marked normal tissue effects were reported in 9.9% of patients receiving the 40 Gy schedule, 15.4% for the 27 Gy schedule, and 11.9% for the 26 Gy schedule . Patient and photographic assessments indicated a higher risk of normal tissue effects for the 27 Gy schedule compared to the 40 Gy schedule, but not for the 26 Gy schedule .
Cosmetic Outcomes and Toxicity
Cosmetic Results
The IRMA trial compared accelerated partial-breast irradiation (APBI) with whole-breast irradiation (WBI) and found that adverse cosmetic outcomes were more frequent in the APBI group. At 5 years, 14% of APBI patients reported adverse cosmesis compared to 9.8% of WBI patients.
Late Toxicity
Late soft tissue and bone toxicities were significantly higher in the APBI group. Specifically, grade ≥3 late soft tissue toxicity was observed in 2.8% of APBI patients versus 1% of WBI patients, and grade ≥3 late bone toxicity was 1.1% in the APBI group compared to 0% in the WBI group. There were no significant differences in late skin and lung toxicities between the two groups.
Conclusion
The 5-day radiation schedule for breast cancer, particularly the 26 Gy in five fractions regimen, has been shown to be non-inferior to the traditional 3-week schedule in terms of local tumor control. However, it is associated with a higher incidence of normal tissue effects, particularly for the 27 Gy schedule. Cosmetic outcomes and late toxicities also vary, with APBI showing higher rates of adverse cosmesis and late soft tissue and bone toxicities compared to WBI. These findings highlight the importance of considering both efficacy and side effects when choosing a radiotherapy schedule for breast cancer treatment.
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