Relevance and practicability of internal mammary sentinel node biopsy for breast cancer

Recent observations in breast cancer patients undergoing sentinel lymph node (SLN) mapping, in which drainage can be traced to the internal mammary node (IMN) chain, have renewed interest in the staging and treatment of the disease. This paper discusses the relevance of internal mammary SLN biopsy and suggests an optimal procedure for the identification of the SLN in the IMN chain.

Axillary lymph node (AX) and IMN status have similar predictive relevance for survival, while the involvement of IMNs has prognostic value for AX-negative as well as AX-positive patients. Although parasternal recurrence is fortunately rare after modified radical mastectomy or breast conserving surgery, if left untreated it not infrequently develops as clinically evident disease in patients with histologic involvement of IMNs. "Hot" internal mammary SLNs can be identified by means of lymphoscintigraphy and gamma-detection probe after peritumoral injection of radioisotopes. A positive internal mammary SLN biopsy would be an indication for internal mammary radiotherapy as well as adjuvant systemic treatment. However, the reported incidence of positive internal mammary SLNs is still lower than expected because the spread of radioactivity does not necessarily coincide with nodal involvement.

Internal mammary SLN biopsy has proven to be relevant but not yet fully practical because more data are needed on the collection of a "Hot" internal mammary SLN and on pathologic involvement. This means that internal mammary SLN biopsy should be regarded as still investigative.