Adjuvant regional nodal irradiation did not improve outcomes in T1-2N1 breast cancer after breast-conserving surgery: A propensity score matching analysis of BIG02/98 and BCIRG005 trials

Abstract

Aim To determine whether the addition of regional nodal irradiation (RNI) to whole-breast irradiation (WBI) would improve outcomes over WBI alone in T1-2N1 breast cancer after breast-conserving surgery (BCS) and adjuvant systematic therapy. Methods Data were obtained from two randomized controlled trials (NCT00174655 and NCT00312208). Univariate and multivariate Cox-regression analysis were performed to investigate predictors for overall survival and disease-free survival. A 1:1 propensity score matching (PSM) analysis was applied to eliminate selection bias. Results With median follow-up 80 months (range: 3–155 months), the 5-year local regional recurrence in the WBI group was 2% vs. 5% ( p = 0.28) in the WBI + supraclavicular radiotherapy, and the rate of 5-year distant metastasis in the WBI group was 7% vs. 13% in the WBI + supraclavicular radiotherapy ( p = 0.0748); In addition, the 5-year local regional recurrence in the WBI group was 3% vs. 9% ( p = 0.19) in the WBI + internal mammary irradiation (IMI); However, the rate of 5-year distant metastasis in the in the WBI group was significantly lower than that in the WBI + IMI (8% vs. 24%, p = 0.036). After PSM, cox-regression analysis indicated that neither RNI nor IMI in combination with WBI in T1-2N1 breast cancer was associated with an improved overall survival and disease-free survival when compared to WBI alone. Conclusion The addition of RNI to WBI in T1-2N1 breast cancer after BCS and adjuvant systematic therapy did not improve outcomes in comparison with WBI alone. Further studies are still needed to identify patients who would most benefit from RNI in this patient population.

Risk factors to identify the indication for regional nodal irradiation in T1-2N1M0 breast cancer: A joint analysis of 4,243 real-world cases from two institutions

“…The value of RNI in patients with T1-2N1M0 breast cancer remains a topic of great clinical relevance and controversy. Our results showed that the 5-year LRR was 7.2% in patients with T1-2N1M0 breast cancer without RNI, which is consistent with other contemporary studies showing that the 5-year LRR was less than 10% (9,(17)(18)(19). Given the low LRR risk, the necessity of RNI in T1-2N1M0 breast cancer has been questioned.…”

“…Because IMN involvement occurred more frequently in patients with medially located tumors ( 31 ), coverage of IMN in RNI might be considered. One previous study showed that supraclavicular or IMN irradiation alone did not improve survival outcomes in N1 breast cancer ( 18 ). A Danish study showed that additional IMN irradiation significantly improved the OS in patients with one to three positive nodes and medially located tumors ( 32 ).…”

Breast-conserving in centrally located breast cancer patients confirmed safe by SEER based study

“…The PSM was used to eliminate the effects of non-random statistics. We used 1:1 nearest-neighbor matching, setting the caliper as 0.02 to balance the baseline covariates within the groups (12). The 79,214 patients' characteristics between central and noncentral groups were compared by chi-square test.…”

Radiotherapy instead of axillary lymph node dissection: evaluation of axillary lymph node dose coverage with whole breast radiotherapy

“…Tangent field RT and systemic therapy provide good locoregional control for low risk cN0 patients with 1–2 positive SLN, in spite of the inadequate dose coverage of level I–II regions [ 2 ]. In the propensity score matching analysis of BIG02/98 and BCRG005 trials regional nodal irradiation (RNI) did not improve outcomes [ 25 ]. However, in these trials RNI was given after ALD and the target volume was the anatomic site of the dissected axillary lymph nodes.…”