Predictors of 4 or More Positive Axillary Nodes in Patients with Node- positive T1-2 Breast Carcinoma: The Indications for Adjuvant Irradiation

Administering adjuvant irradiation to the level III axilla and supraclavicular fossa (SCF) is indicated for those patients who undergo the standard level I-II axillary dissection and who have four or more positive axillary nodes or T3-4 primary disease.(1-3) The risk of failure in the axillary apex or SCF is less than 5% for the patients who have T1-2 primary tumors and fewer than 4 involved axillary nodes, and these regions are generally not included in the radiation field.(4-6) The standard treatment for patients with a positive sentinel lymph node (SLN) is complete level I-II axillary lymph node dissection (ALND). However, for various reasons, some node-positive patients are referred for adjuvant radiotherapy without undergoing axillary dissection. The appropriate treatment for these patients is currently unclear. In these circumstances, some radiation oncologists include a portion of levels I and II of the axilla in the standard tangential fields and they treat the breast after lumpectomy or local excision by extending the cranial border of these fields to near the humeral head. This technique can include >80% of the axillary level I and II lymph nodes.(7) Alternatively, others comprehensively treat these patients with a third anterior field to encompass the axillary apex and SCF, with or without a posterior boost field at the mid-axilla. Yet irradiating the high axilla and SCF has been shown to increase the treatment morbidity, including causing pneumonitis, lymphedema, brachial plexopathy and significant shoulder-joint dysfunction.(8-10) Radiation oncologists are faced with the Purpose: We evaluate the predictors of 4 or more involved axillary nodes in patients with node-positive T1-2 breast carcinoma to select a group of patients who are indicated for adjuvant irradiation of the level III axilla and supraclavicular fossa (SCF). Methods: We analyzed 286 patients with positive axillary nodes and who were without distant metastases and who underwent breast conserving surgery and axillary lymph node dissection or modified radical mastectomy. We investigated the relationship between the patients and the tumor factors and 4 or more positive axillary nodes. Results: On the multivariate logistic-regression analysis, an increased tumor size (p=0.002), the presence of lymphovascular space invasion (LVSI) (p<0.001) and a palpable mass p<0.001) were positively associated with involvement of 4 or more axillary lymph nodes. In our study, 86.1% of the patients with all the unfavorable factors had involvement of 4 or more nodal metastases. Conclusion: Our data suggest that for patients with node-positive T1-2 breast cancer, the presence of 4 or more involved nodes is frequently observed for the patients with an increased tumor size, the presence of LVSI and a palpable mass at the time of diagnosis, and we recommend that they undergo irradiation of the high axilla and SCF for adjuvant care, if they do not undergo complete axillary dissection.