Abstract P6-10-10: Association between mammographic density and breast cancer subtypes among Chinese women

Epidemiological studies have shown that associations between breast cancer risk and risk factors vary by tumor pathology such as estrogen receptor (ER), progesterone receptor (PR), and human epidermal growth factor receptor 2 (HER2) status. Mammographic density (MD) is a strong risk factor for breast cancer, but data on the association between MD and breast cancer subtypes have been inconsistent and most studies have been conducted among Western women. The goal of this study was to evaluate the association between MD and breast cancer subtypes in an Asian population where the proportion of dense breast tissue is higher but the overall breast cancer incidence rate is much lower compared with Western countries. Breast cancer cases from a cancer hospital in Beijing, China with MD and ER, PR, and HER2 immunohistochemical (IHC) data were included in this analysis. To reduce subtype misclassification, we excluded cases that were HER2 2+ for IHC but had no FISH data. Tumor subtypes were defined as Luminal A (ER+ or PR+ and HER2-, N=376), Luminal B (ER+ or PR+ and HER2+, N=97), HER2-overexpressing (ER- and PR- and HER2+, N=71), and triple negative (TN, ER- and PR- and HER2-, N=66). MD was assessed on digital mammograms and categorized into four levels using the Breast Imaging Reporting and Data System (BI-RADS) scoring system (a=almost entirely fat, b=scattered fibroglandular densities, c=heterogeneously dense, and d=extremely dense). Because there were few cases with almost entirely fat breasts, we combined MD levels "a" and "b" as our reference group. Polychotomous logistic regression was used to assess the association between MD and breast cancer subtypes with the adjustment of age, menopausal status, parity, age at menarche, and body mass index (BMI) since all these variables showed significant inverse associations with MD (P=0.002 for age at menarche and P<0.0001 for all others). Compared with luminal A cases, cases with HER2-overexpressing tumors were significantly more likely to have extremely dense breasts (Odds ratio [OR], 2.6; 95% confidence interval [CI], 1.2-5.7). Cases with luminal B (OR, 2.1, 95% CI, 1.2-3.9) and TN (OR, 2.9, 95% CI, 1.5-5.8) tumors had significantly higher proportions of heterogeneously dense but not extremely dense tissue compared with luminal A cases. Our data suggest that higher MD is associated with more aggressive tumor subtypes, particularly the HER2-overexpressing subtype among Chinese breast cancer cases. If confirmed in larger studies, these results may provide insight into the higher incidence rates of HER2-overexpressing breast cancer seen among young Asian American and Asian women.

Citation Format: Yang XR, Li J, Li E-N, Guida JL, Li M, Sung H, Lu N, Hu N, Gierach GL. Association between mammographic density and breast cancer subtypes among Chinese women. [abstract]. In: Proceedings of the Thirty-Eighth Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2015 Dec 8-12; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2016;76(4 Suppl):Abstract nr P6-10-10.

Ventral hernia repair using allogenic acellular dermal matrix in a swine model

BACKGROUND

This study was designed to assess the long-term efficacy of allogenic acellular dermal matrix (ADM) used as an interpositional graft for ventral hernia repair in a swine model.

METHODS

We created 12x4-cm full-thickness abdominal wall defects in 22 Yucatan miniature pigs. The defect was repaired with either two 6x4-cm pieces of AlloDerm (acellular dermal matrix processed from pig skin in order to avoid a xenogenic response, LifeCell Corporation, Branchburg, NJ USA) (n = 12), or expanded polytetrafluoroethylene mesh (ePTFE) (Gore-Tex, W.L. Gore & Associates, Inc., Newark, DE USA) (n = 10). In six pigs, a separate 3-cm fascial incision was made, which was then suture repaired as a control for tensiometry testing. The surgical sites were evaluated at either 3 months or 9 months for the presence of a hernia, stretching of the implant, adhesions, vascularity, and biomechanical strength.

RESULTS

Two hernias occurred in both the ADM and the ePTFE groups. There was minimal stretching of the implants and minimal adhesions in both groups. Fluorescein testing and histology indicated vascular ingrowth into the ADM. There was no statistical difference between the mean breaking strengths of the ADM-fascial interface (106.5 N +/- SD 40.1), the interface between two pieces of ADM (149.1 N +/- SD 76.7), and the primary fascial repair (108.1 N +/- SD 20.9) at 9 months. The ADM-fascial interface had a significantly higher breaking strength than that of the ePTFE-fascia interface (66.1 N +/- SD 30.1) (P = 0.017, t-test, P = 0.043 Wilcoxon rank sum test).

CONCLUSIONS

In this study, we were unable to demonstrate a difference between ADM and ePTFE in their ability to repair ventral hernias at 9 months in a swine model. The ADM additionally supports vascular ingrowth and exhibits increased breaking strength at the fascia-implant interface.