Distribution of involved regional lymph nodes in recurrent and locally advanced breast cancer and its impact on target definition

Objective The frequency and the anatomic distribution of involved regional nodes in recurrent and locally advanced breast cancer were analyzed, in order to evaluate the rational of conventional regional node radiation technique and provide evidence for target definition of breast cancer . Methods Patients with recurrent or locally advanced breast cancer who were treated in our hospital from August 2003 to December 2009 were included in this study. 111 patients had contrast enhanced chest CT images of the whole regional nodes before treatment. The regional nodes were categorized into 8 anatomical substructures including medial and lateral supraclavicular nodes ( SC-M, SC-L), axilla nodes ( ALN )- Ⅰ , Ⅱ , Ⅲ,infraclavicular nodes (IFN), Rotter's nodes (RN) and internal mammary nodes (IMN). The frequency of involvement and anatomical distribution of the involved nodes on CT images were analyzed. Results A total of 111 patients were enrolled this study and 199 anatomical substructures with involved nodes were identified. The frequency of involvement were :SC-M 33, SC-L 21, ALN- Ⅰ 30, ALN-Ⅱ 25, ALN-Ⅲ + IFN 35, RN 27, IMN 28. Supraclavicular region and axilla were the most frequently involved area (72. 3% ).The average depth of the SC-M and SC-L nodes was 33.48 mm ± 10. 57 mm and 45.62 mm ±20. 45 mm,and 51.5% and 71.4% of the SC-M and SC-L nodes were located more than 3 cm deep from the skin. The axilla nodes were located cranial and caudal to the axillary vein in 5 and 20 locally advanced breast cancer patients and in 64 and 28 patients who received prior axillary dissection. The majority of involved IMN was located within the first 3 intercostal spaces (26/28). The average distance between the center of involved IMN and chest skin was 24. 23 mm ± 10. 28 mm. The average distance between the center of involved IMN and midline of the body was 29. 38 mm ±6. 7 mm. The center of involved IMN was 6.19 mm ±5.73 mm lateral and 5.73 mm ± 4. 56 mm posterior to the internal mammary vessels. Conclusions Conventional field design is unlikely to provide sufficient dose to the entire risk region because of individual differences.Individualized treatment planning based on CT would become feasible with increasing knowledge of natural risk of nodal involvement. Key words: Breast neoplasms;  Target volume delineation;  Regional lymphnodes