The anatomically correct incidence of internal mammary node drainage on lymphoscintigraphy.
Authors: Spillane AJ , Noushi F , Cooper R , Uren RF 
Published: December 2010

Abstract #1024

Background: The documented rate of IMN drainage on lymphoscintigraphy ranges from &lt;2% to 38% depending on the technique utilized and the radio-isotope used. The relevance of IMN drainage is debated. Surgeons and oncologists who work in an environment where IMN drainage is rare have no practical perspective of how it may impact on individual patient management decisions. Those who work in an environment where up to 38% of cases drain to the IMN are familiar with the impact on management. A recently published anatomical model of breast lymphatic drainage1 correlates well with the findings on lymphoscintigraphy using a peritumoral injection technique but not with superficial injections.&#x2028; Methods: Two separate nuclear medicine facilities' prospective data bases were used to document their IMN drainage rates on lymphoscintigraphy over 15 years and 7 years respectively. Lymphoscintigraphy was done using a technique of peritumoral injection with antimony sulfide colloid. Review of the literature was done to identify the parameters indicating success at demonstrating IMN drainage and the rates of positivity of IMN.&#x2028; Results: The 2 facilities identified axillary sentinel nodes in 95.5% and 93.6% of cases respectively. Facility U had a 34% IMN drainage rate. It varied between 28% and 48 % over the 15 year period (first 9 years 316 cases at a rate of 40%; later 6 years 1438 cases at 33%). Facility C had an overall IMN drainage rate of 29%. The initial drainage rate of 19% fluctuated to 36% over the 7 year period (first 4 years 186 cases at 25%; later 3 years 421 cases at 31%). The increasing IMN drainage rate at Facility C was associated with increasing case volume and modifications in technique, quality of collimators and gamma cameras. Literature review shows rates of IMN drainage vary widely but not exceed of 38%. Transpectoral IMN biopsy positivity rates range from 13 – 25% and are not related to the rate of IMN drainage at the facility.&#x2028; Conclusion: Recent anatomical models of breast lymphatic drainage1 correlate well with both facilities' patterns of IMN drainage. These facilities results and the available literature suggests that the true rate of IMN drainage is around 35%. Technical modifications resulted in Facility C converging on this parameter. High quality lymphatic mapping with peritumoral injections is the best known demonstrator of breast lymphatic anatomy. An institution finding lower rates of IMN drainage reflects technical issues and not the true anatomy of the breast. The remarkably constant rate of positive lymph nodes irrespective of the IMN drainage rate is supportive of the above conclusions. There is compelling contemporary evidence that IMN positivity is a strong predictor of worse prognosis and this information is important information when making adjuvant therapy decisions.&#x2028; 1. Suami H, Pan WR, Mann GB, et al: The lymphatic anatomy of the breast and its implications for sentinel lymph node biopsy: a human cadaver study. Ann Surg Oncol 15:863-71, 2008.

Citation Information: Cancer Res 2009;69(2 Suppl):Abstract nr 1024.