Abstract 5745: Hormonal risk factors in breast cancer in relation to histopathology: A clue to tissue of origin of the tumor

Abstract

Abstract Background. The association between breast cancer (bc) and hormonal influence is well known. Associations to certain hormonal risk factors in the different histopathological bc types could indicate that exposure to hormones during different stages of breast development could give rise to different types of bc. We wanted to get an overview of several risk factors with a known or a possible hormonal effect in relation to the classical histopathological groups of breast cancer to explore our hypothesis. Materials and method. A clinical series of 1676 patients diagnosed with bc were investigated. In the present study we investigated possible associations between classical histopathological bc and possible risk factors such as occurrences of spider telangiectasias, varicose veins, HRT-ever use, number of childbirths and combined oral contraceptive pill (COCP) before first child. Analyses were performed using a binary logistic regression model, and were adjusted for age at diagnosis and for each factor simultaneously. A confidence interval (CI) of 95% was used. Results. COCP use before first child was significantly positively associated with pure invasive ductal bc and invasive ductal bc combined with ductal carcinoma in situ (ductal/DCIS), odds ratio (OR) 1.5 (CI 1.2-2.1) and 3.3 (CI 1.6-7.0) respectively. Comedo bc was associated with a large number of childbirths (p-value 0.004), whereas mucinous bc (ductal bc was borderline significant p-value 0.006), on the other hand, was associated with a low number of childbirths (p-value 0.004). HRT-ever use was associated with an increased risk for pure lobular, mixed lobular, mixed ductal bc, OR 1.5 (CI 1.0-2.3), 1.9 (1.2-3.1) and 1.7 (1.2-2.5) respectively. The occurrence of spider telangiectasias was nonexistent in comedo breast cancer, but increased the risk of ductal cancer/DCIS (OR 4.7 (CI 2.2-10.1)). Varicose veins were significantly associated with pure comedo (OR 2.8(CI 1.2-6.8) and tubular bc (OR 4.4(CI 1.3-15.4)). Conclusions. Before first pregnancy the lobules are not completely developed, therefore COCP use before first pregnancy possibly affects the duct system to a larger extent then the lobules, in line with our findings. However, HRT is used by women in menopause, and could therefore have a greater influence on the lobules. The association between HRT use and lobular bc has been shown in other studies. Varicose veins are thought to be induced by an increased hormonal level, either during pregnancy or menopause, and could be used as an indicator of large hormonal exposures or specific phenotypes regarding the estrogen receptor. Different histopathological groups respond differently to the hormonal risk factors in the present study, which could indicate that there is a slight difference in the biology between them. We propose that based on risk factors it might be possible to locate the origin of different tumors within the breast. Note: This abstract was not presented at the AACR 101st Annual Meeting 2010 because the presenter was unable to attend. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 5745.