Evaluating Omitting of Internal Mammary Irradiation Among Early Stage Intermediate Risk (N1) Breast Cancer

This study is a phase II open label, non-inferior randomized controlled trial, we aimed to compare the safety and effectiveness difference of whole breast/chest wall irradiation + IMI+SVC irradiation vs whole breast/chest wall irradiation + SVC irradiation among clinical high risk, genomic low risk of N1 breast cancer. In previous studies, 28 gene classifier has been developed and established to predict local/regional recurrence. The 28 gene classifier was combined with 18 cancer gene and 10 reference gene. The 18 cancer gene includes BLM, TCF3, PIM1, RCHY1, PTI1,DDX39, BUB1B, STIL, TPX2, CCNB1,MMP15, CCR1,NFATC2IP, TRPV6,OBSL1, C16ORF7,DTX2, and ENSA. The expression of RCHY1, PTI1, ENSA, and TRPV6 is associated with better tumor biology and disease control. The remaining 14 genes are associated with poor outcomes. By using the 18-gene scoring algorithm defines the risk of recurrence as: low risk or high risk. A total of five clinical factors \[age（≤40 vs. \>40, number of positive lymph node（1-2 vs. 3）, grade(I-II vs. III), tumor size (T1-T2), ki-67(\<14% vs. ≥14%)\] were identified to be significantly associated with outcomes of breast cancer in our previous study. And patients with more than 2 risk factors were defined as clinical high risk. Clinical high risk participants (≥2 factors) with low-risk scores will be randomized to whole breast/chest wall irradiation + IMI+SVC irradiation or whole breast/chest wall irradiation + SVC irradiation