Extent of metastatic axillary involvement in 1446 cases of breast cancer.

One thousand, four hundred and forty-six patients with carcinoma of the breast treated with Halsted mastectomy (167), Patey mastectomy (732), and conservative surgery with axillary dissection, either at the same time (340), or separately (207), were evaluated with regard to the number and distribution of axillary lymph nodes. A total of 29,378 were removed and examined, on average 20.3 per patient. The average number of nodes was 13.5 at the first level, 4.5 at the second and 2.3 at the third. The same number of nodes were removed in patients treated with extensive surgery, such as Halsted mastectomy and limited surgery such as lumpectomy and in independent axillary dissection. In 839 cases metastases were found in the axilla. The average number of involved nodes was 6.4. Out of 839 patients, the first level was the site of metastases in 828, the second level in 364 and the third in 187. When a single lymph node was involved, it was nearly always at the first level. In only 11 cases, were the second and/or third levels invaded without metastases at the first level. Therefore, the percentage of cases with skipping metastases was very low (1.3%). It appears from the present data that the spread of breast cancer to the axilla follows a regular pattern; the first level is invaded first, whilst in most cases, the second and third levels are involved only when the first is substantially affected.