Breast cancer: primary tumor characteristics related to lymph node involvement

From November 1st 1977 to August 31st 1978, 842 consecutive patients with operable breast cancer were observed at the National Cancer Institute of Milan. Characteristics of the primary tumor and the status of regional lymph nodes were evaluated at clinical and postsurgical examination: it was found that qualitative characteristics of the primary were properly defined by clinicians, who usually overestimated maximum diameter of the primary. The status of regional lymph nodes is not reliable at clinical examination: 34.5% of clinically uninvolved nodes were found to contain metastatic growth at histologic examination. Age of patients, maximum diameter of the primary, histologic type and quadrant of origin of the primary tumor were significantly related to the frequency of regional node metastases. Multifactorial analysis showed that the last three factors were independent variables, while age, which is significant by itself, loses importance when adjusted by at least one of the other three factors. Frequently of extension of node metastases beyond the lymph node capsule was found to be related to the number of involved nodes: maximum diameter, histologic type and site of origin are significantly related to the frequency of extracapsular invasion. This study confirms that the evaluation of the status of regional lymph nodes is not reliable at clinical examination and indicates that characteristics of the primary may be useful in predicting regional lymph node involvement. The direct correlation between the number of involved nodes and the frequency of infiltration beyond the capsule suggests that prognosis of patients with positive nodes depends more on this factor than on the number of involved nodes.