Incidence and potential significance of internal mammary lymphadenopathy on computed tomography in patients with a diagnosis of primary breast cancer

Introduction: The importance of internal mammary nodes (IMNs) in the staging and treatment of breast cancer patients is controversial. Methods: A retrospective cohort of patients diagnosed with primary breast cancer over a 4-year period (January 2009 to December 2012) was assessed. The number and size of any IMNs visible on spiral computed tomography (CT) were recorded. Results: A total of 830 patients were diagnosed with primary breast cancer within the identified time frame, of which 150 patients met the inclusion criteria. Of these 42% (63) had IMNs present, although the majority were small (<5 mm). However, 16% (25) had larger nodes, greater than 5 mm in short axis, present on CT. Significantly more patients with the presence of large (>5 mm) IMNs had more advanced disease with CT evidence of other distant spread. Conclusion: We have demonstrated that IMNs are present in a substantial number of our primary breast cancer patients. We suggest that further histological research is required to establish reliable CT size criterion for pathological IMNs. In addition, routine imaging of the IM chain, as well as axilla, should be considered in the staging of breast cancer.