Routine dissection of the internal mammary chain sentinel node is safe and assists treatment planning for both chemotherapy and radiation therapy


We recently reported a study, which described the results of internal mammary chain (IMC) biopsy, identifying factors that predict 'hot spots' and nodal metastases for patients in whom mapped IMC nodes were routinely dissected. Ninety of 490 patients (18.4%) had IMC sentinel lymph nodes (SLNs) identified by lymphatic mapping and dissected, and 20 of these (22.2%) were found to have metastases. Predictors of IMC positivity included age <35 years (p=0.063), grade 3 histology (p=0.018) and lymphatic vascular invasion (LVI) (p=0.032). Although IMC positivity was more likely with positive axillary nodes, this trend was not significant. Our policy of dissecting the IMC sentinel node allows for improved staging, potential improvements in regional control, and the potential to increase long-term survival and the identification of patients who may benefit from IMC radiation. Although the incidence of a recurrence in the IMC region is uncommon, the morbidity associated with extension of a recurrent node into the sternum or adjacent rib is significant and subsequent disease control can be difficult. Routine dissection of the IMC sentinel node is safe and assists treatment planning for both chemotherapy and radiation therapy. Where IMC hot spots are not dissected, we predict IMC positivity of 50% or more for young women (<35 years) or women with high grade or LVI positive tumours, and these women may benefit from more intensive chemotherapy and radiotherapy to the IMC.

 

Bibliographic Reference

Coombs NJ et al.: "Internal mammary sentinel nodes: Ignore, irradiate or operate?", Eur J Cancer. 2009, March 6; 45(5): 789-794

 

John Boyages

New South Wales Breast Cancer Institute,  Westmead Hospital, New South Wales, Australia