Analysis of breast cancer location using breast MRI

Abstract

Introduction: The location of a primary cancer could affect tumor growth patterns and have a prognostic significance. This study was to compare the location of triple-negative breast cancers with that of estrogen receptor (ER)-positive breast cancers using magnetic resonance (MR) imaging and to provide a radiogenomic analysis linking tumor location to global gene expression patterns. Methods: The locations of 1102 primary breast cancers (256 triple-negative and 846 ER-positive) in 1090 women (mean, 52.1 years) were reviewed using MR imaging. Mediolateral and anteroposterior locations were determined, and absolute and normalized distances of the tumor from the chest wall were recorded. The association between breast cancer subtype and tumor location was evaluated using multiple linear regression analysis. A subset of 53 cancers was analyzed for global gene expression profiling to correlate gene expression and location data. We divided samples into two groups according to the tumor distance from the chest wall (prepectoral group, tumors located from the chest wall < 1cm

control group, tumors located from the chest wall ≥ 1cm). Results: The anteroposterior location was significantly different between triple-negative and ER-positive breast cancers (P = .001): 55% (140/256) of the triple-negative breast cancers had a posterior location, whereas 44% (370/846) of the ER-positive breast cancers had a posterior location. Triple-negative breast cancers were significantly closer to the chest wall than ER-positive breast cancers in absolute (1.8 cm, 95% confidence interval [CI]: 1.64 - 2.04 vs. 2.3 cm, 95% CI: 2.17 - 2.43

P < .0001) and normalized (0.21, 95% CI: 0.19 - 0.23 vs. 0.25, 95% CI: 0.24 - 0.27

P < .0001) distances. Multiple linear regression analysis revealed that age, palpability, mammographic density, and triple-negative subtype were significantly associated with absolute and normalized distances from the chest wall (all P < .05). A number of genes (277 genes in triple-negative cancers

2024 gene in ER-positive cancers) showed a significantly different expression in prepectoral tumors compared to control group. Gene ontology analysis revealed that 17 gene descriptions in triple-negative cancers and 31 gene descriptions in ER-positive cancers were over-represented. Conclusions: Our results show that triple-negative breast cancers have a tendency toward a posterior location compared with ER-positive breast cancers. Age and mammographic density are also associated with posterior location of the tumor. Radiogenomic analysis of breast cancer linking tumor location determined by MRI to underlying global gene expression patterns shows that information about tumor location can be systemically correlated with the global transcriptomic level in breast cancer.