Breast Cancer and Internal Mammary Sentinel Nodes: A Meta-Analysis

The management of internal mammary (IM) nodes in breast cancer lacks a well-defined consensus. Lymphoscintigraphy identifies up to one-third of breast cancer patients with extra-axillary drainage, which is mainly located in the IM chain. Our aim in this meta-analysis is to identify the lymphoscintigraphy technique variables that effect IM node identification. An internet database was utilized to review articles concerning sentinel nodes and breast cancer from 1993 through the end of 2011; 74 articles met our inclusion criteria. The total number of patients included was 22959. We grouped the citations by injection location and injection material. We then analyzed the rate of identification of IM nodes according to these groupings and their subsets. The overall IM identification rate using the random effect model was 9%. The injection location had the most significant impact on IM identification rate; the deeper injections were associated with the highest rate of identification. Variation in IM identification was associated with the particle size of injection material; the smaller particle size group had a higher rate of identification. Increased dose of the tracer was also associated with increased identification rate. The use of smaller particle size tracers and a deeper injection location achieve the highest IM identification rate. The dose of the tracer also increased the identification rate. These observations can help in the selection of patients for IM sentinel node biopsy, which can affect their prognosis and treatment management.