Significance of axillary lymph node extranodal soft tissue extension and indications for postmastectomy irradiation

BACKGROUND, Extranodal soft tissue extension of axillary lymph node metasta ses (ETE) has been considered an indication for postmastectomy radiotherapy including the axilla. However, it is unclear whether patients with ETE are at an increased risk of axillary recurrence. METHODS, From a single institutional database of 2362 patients with breast carcinoma treated between 1974-1994, a total of 487 patients who underwent mastectomy for lymph node positive, infiltrating (T1-T3) breast carcinoma w as found. All the patients had pathologically confirmed axillary lymph node metastases and negative surgical margins; none had received postoperative irradiation. Of these patients, 50 had histologically documented axillary E TE. Forty-three patients had a minimum follow-up of at least 1 year and com prise the study population. The median follow-up time of surviving ETE posi tive patients was 79 months. Twenty five patients (58.1%) received adjuvant systemic therapy. Sites of first failure were local or distant. Local fail ure was categorized further as chest wall failure, axillary failure, suprac lavicular lymph node failure, or internal mammary lymph node failure. RESULTS, For the 43 patients with ETE, the median patient age was 59.5 year s (range, 38-81 years) and the median tumor size was 3.6 cm (range, 0.5-12. 0 cm). The median number of positive axillary lymph nodes was 6 (range, 1-3 6 lymph nodes) versus 2 (range, 1-30 lymph nodes) for all T1-T3 ETE positiv e patients compared with ETE negative patients (P < 0.001). The risk of ETE increased significantly with increasing numbers of axillary lymph node met astases (P < 0.001). Of the patients with ETE, 16 (37.2%) developed recurre nt disease. ETE positive patients with disease recurrence had significantly greater numbers of positive axillary lymph nodes (median, 10 lymph nodes) than those patients who were recurrence free (median, 4 lymph nodes) (P = 0 .02). The site of first failure was local in 7 patients (16.3%) and distant in 9 patients (20.9%). All patients with local recurrence had chest wall f ailures; there were no isolated lymph node recurrences. The only simultaneo us local and distant failure was in one patient presenting with supraclavic ular and intraabdominal metastases. CONCLUSIONS. The risk of axillary recurrence, either as an isolated event o r as part of simultaneous failure, is extremely low, even in patients with ETE. These data suggest that patients with ETE frequently have higher numbe rs of positive axillary lymph nodes and on that basis are at risk for local recurrence and as a rule would be considered for postmastectomy irradiatio n. However, these data suggest that the presence of ETE is not an indicatio n for routine postmastectomy axillary lymph node irradiation. Cancer 1999;8 6:1258-62. (C) 1999 American Cancer Society.