Contact of the Tumor with the Internal Mammary Perforator Vessels as Risk Factor for Internal Mammary Lymph Node Involvement Based on Dynamic Contrast Enhancing MRI Imaging in Breast Cancer Patients.
Int J Radiat Oncol Biol Phys 2023;
117:e187. [PMID:
37784816 DOI:
10.1016/j.ijrobp.2023.06.1046]
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Abstract
PURPOSE/OBJECTIVE(S)
Distant metastasis free and overall survival of high-risk breast cancer patients can be improved with irradiation of the lymphatic system. However, inclusion of internal mammary region (IMN) markedly increases the dose to the heart. Hence, an estimation of the individual risk of subclinical involvement is necessary in order to balance the oncological benefit versus the cardiac toxicity. In randomized studies the risk stratification for IMN involvement is mainly based on the tumor location (medial, central vs. lateral). The aim of this study was to evaluate whether the contact of the tumor with the internal mammary perforator vessels (IMPV) is an additional risk factor for IMN involvement.
MATERIALS/METHODS
For this trial we retrospectively examined 104 sets of pre-treatment dynamic contrast enhanced magnetic resonance imaging (DE-MRI) scans of locally advanced breast cancer patients. All patients had ipsilateral clinical suspect lymph nodes in the axillary region and either positive (n = 52) or negative lymph nodes (n = 52) in the internal mammary region. Based on the DE-MRI we assessed the tumor location as well as contact to the internal mammary perforating vessels (IMPV). Contact between tumor and IMPV was classified into either predominant, minor or no contact. Criteria for a predominant IMPV contact was defined as: main vessel contact or contact to multiple (> = 5) side branches.
RESULTS
The tumor location of IMN+ patients were medial in 19.2% (10/52), central in 26.9% (14/52), lateral in 28.8% (15/52) and multicentric in 25.0% (13/52) of. In IMN- patients, tumor location was medial in 9.6% (5/52), central in 26.9% (14/52), lateral in 42.3% (22/52) and multicentric in 21.2% (11/52) in IMN- patients. The tumor size ranged from T1-T4 with most patients staged as T2 (48.1% (IMN+) vs. 38.5% IMN-). Most patients had hormone receptor positive / Her2neu negative disease (36.5% (IMN+) vs. 46.2% (IMN-). 100 % of tumors in IMN+ patients had contact with IMPV: in 94.2% (49/52) criteria for predominant IMPV contact was fulfilled; in the remaining 3 cases (5.8%) the tumor had minor IMPV contact. In IMN- patients however, 36/52 of cases (69.2%) had direct IMPV contact. Predominant contact was found in only 23.1% (12/52), minor IMPV contact in 46.2% (24/52).
CONCLUSION
Predominant contact of the tumor with IMPV appears to be a potential risk factor for IMN involvement in breast cancer patients and could be used for stratification for IMN-irradiation in future trials.
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