Background: Recent studies suggested that ALND (axillary lymph node dissection) can be avoided in breast cancer patients with limited SLN (sentinel lymph node) metastasis. However, these trials included only several invasive lobular carcinoma (ILC) cases, and the validity of omitting ALND for ILC remains controversial. Here, we examined whether omitting ALND is feasible in ILC treatment.
Methods: A total of 3771 breast cancer patients underwent surgery for breast cancer at the Aichi Cancer Center Hospital between January 2006 and December 2015. We excluded patients with neoadjuvant therapy or without axillary management, and identified 184 ILC patients and 2402 invasive ductal carcinoma (IDC) patients. We compared SLN and non-SLN metastasis rates and the number of total ALN metastases between the ILC and IDC cohorts, and we examined the factors that influenced non-SLN metastasis in the SLN micrometastasis group.
Results: SLN biopsies were performed in 171 (93%) ILC and 2168 (90%) IDC cases, and 31 (18%) ILC and 457 (21%) IDC cases were SLN micrometastasis and macrometastasis (p = 0.36). Among SLN macrometastasis patients, 17 (68%) ILC cases and 163 (46%) IDC cases showed non-SLN metastasis (p = 0.03). The number of non-SLN metastases was greater in ILC cases compared with IDC cases. Multivariate analysis showed that ILC was the influential factor predicting non-SLN metastasis in patients with SLN macrometastasis.
Conclusion: ILC cases had more non-SLN metastasis than IDC cases among SLN-positive cases, and ILC was an important factor for the prediction of non-SLN positivity in SLN macrometastasis cases. Omitting ALND for ILC with positive SLNs requires more consideration.
Keywords: Axillary lymph node dissection; Breast cancer; Invasive lobular carcinoma; Non-sentinel lymph node metastases.