Axillary Nodal Examination in Breast Cancer: How Much Is Enough? Evidence for a New Minimum

Background: Axillary nodal spread is an established prognostic factor in breastcancer. Axillary nodal dissection and subsequent pathological examination isconsidered the gold standard technique of assessing the axilla for metastatic disease.A minimum of ten level I axillary nodes are required to be examined before anaxillary specimen can be reliably labeled as disease free. This recommendation isbased on a mathematical prediction model and such methodology has certaininherent limitations. In this study, we sought to revisit this concept of minimumnodes required to deem an axilla as true negative by using a linear correlation model.Methods: Medical records of ۱۶۵ consecutive breast cancer patients attending amedical oncology department for adjuvant therapy were assessed for inclusion. Onehundred and forty-five breast cancer patients in clinical stages I-III met the inclusioncriteria. Patients referred after neoadjuvant chemotherapy, breast conservationsurgery, palliative mastectomy, and mastectomy for metastatic disease wereexcluded from the study. The study samples were segregated into groups of ۱-۵, ۶-۱۰, ۱۱-۱۵, ۱۶-۲۰, ۲۱-۲۵, and more than ۲۵ nodes. A linear regression model wasused to assess the association between the nodal positivity and nodal groups. Thespearman rho with P value was calculated for the model. Factors influencing thenodal yield of an axillary specimen were selected from the published literature andthe same variables were evaluated in the study cohort.Results:Atotal of ۱۸۸۲ nodes were harvested from ۱۴۵ axillary specimens and۳۲۰ nodes were positive for metastatic disease. The mean nodal harvest per axillaryspecimen was ۱۱ nodes. The linear correlation model evaluating the associationbetween nodal positivity and total nodal yield showed a spearman correlationcoefficient of Rho = - ۰.۸۲ with P=۰.۰۴.To avoid bias due to the uneven sample size,the nodal ratio was calculated for each group and the linear association modelreapplied to test the association with the total nodal harvest.Aspearman rho of R = -۰.۹۴ with P=۰.۰۰۴ was obtained. The nodal groups tested for significance showedP= ۰.۰۰۰۱ for the group ۱-۱۵ nodes. Evaluation of the factors likely to influencenodal yield showed that age (P=۰.۱۵) and obesity (P=۰.۶۷) had no effect on thenodal harvest. Tumor stage (P<۰.۰۰۱) and operating surgeon (P=۰.۰۰۰۱) had asignificant effect on the total nodal harvest.Conclusions: The recommendation of a minimum of ten axillary nodes to beexamined to determine true negativity of an axillary specimen needs reassessment.Anew minimum of fifteen nodes is suggested before an axillary specimen is reliablydeemed free of metastatic disease.