Risk-Stratified Hypofractionated Radiotherapy After Breast-Conserving Surgery for Early Breast Cancer

Eligible patients with early breast cancer who have undergone breast-conserving surgery will be stratified into a high-risk group or a low-risk group according to the presence or absence of predefined high-risk factors.

Patients in the high-risk group will receive whole-breast irradiation with a simultaneous integrated boost to the tumor bed. The prescribed dose will be 36 Gy in 15 fractions over 3 weeks to the whole breast and 48 Gy in 15 fractions over 3 weeks to the tumor bed.

Patients in the low-risk group will receive partial-breast irradiation. Two hypofractionated schedules may be used: 40.05 Gy in 15 fractions over 3 weeks or 26 Gy in 5 fractions over 1 week.

Patients will be followed during and after radiotherapy to evaluate treatment efficacy, recurrence rates, and acute and late radiation-related toxicities.

Inclusion criteria

• ECOG performance status score of 0 to 2.
• Pathologically confirmed breast cancer, including invasive carcinoma or ductal carcinoma in situ.
• Clinical stage cT0-2N0M0.
• Underwent breast-conserving surgery.
• Negative surgical margins greater than 2 mm.

Exclusion criteria

• Regional lymph node metastasis.
• Distant metastasis.
• Bilateral breast cancer.
• Prior thoracic radiotherapy.
• Life expectancy of less than 5 years.
• Lactating or pregnant women.