Abstract P4-10-07: Breastfeeding experience among breast cancer patients in the modern era
Authors: Gooch JC , Chun J , Jubas T , Guth A , Schnabel F 
Published: May 2019

Abstract
Introduction: In recent years, the uptake of breastfeeding has become more common as it is regarded as healthy and beneficial for both mother and infant. The process of parturition and lactation plays a role in the normal differentiation and development of breast tissue, and multiparity has been associated with a decreased risk for breast cancer. The current study sought to describe the breastfeeding experience of a modern cohort of women with newly diagnosed BC, and to examine the clinicopathologic characteristics of their disease.
Methods: A retrospective review of our institutional Breast Cancer Database from 2009-2017 was performed to identify women with at least one full term pregnancy (FTP). Clinicopathologic and demographic information was recorded, including breastfeeding experience and cumulative duration of nursing. Women were grouped by self-reported breastfeeding experience and duration of breastfeeding for analysis. Pearson's chi-square tests were performed.
Results: Of 1919 patients, 1053 (54.9%) reporting breastfeeding. Breastfeeding increased from a low of 30.4% among women with first FTP (FFTP) in the 1950's to 84.6% with FFTP in the 2010's. There were no significant differences between those who did and did not breast feed with regards to race, family history, BRCA status, pathologic stage, grade, tumor histology, lymphovascular invasion (LVI), multifocality, tumor size or receptor status. When stratified by duration of breastfeeding, the most striking finding was that women who breastfed for &gt;12 months were more likely to have tumors associated with LVI (p = 0.028).
Table– Breastfeeding Experience Among Parous Women with Breast CancerVariableNo Breastfeeding (n=866)Breastfeeding (n=1053)p-valueRace 0.432White648 (74.8%)767 (72.8%) Black73 (8.5%)112 (10.6%) Asian78 (9%)102 (9.7%) Hispanic64 (7.4%)67 (6.4%) Other3 (0.3%)5 (0.5%) Family history272 (31.4%)311 (29.6%)0.397BRCA 1,2 positive23 (2.7%)42 (4.0%)0.108Final Pathology Stage 0.2240190 (21.9%)222 (21.1%) I426 (49.2%)507 (48.1%) II197 (22.8%)229 (21.7%) III40 (4.6%)63 (6.0%) IV1 (0.1%)3 (0.3%) No residual (neoadjuvant)12 (1.4%)29 (34.1%) Invasive Grade 0.127Low92 (14.1%)120 (15.3%) Intermediate371 (56.7%)398 (50.6%) High191 (29.2%)268 (34.1%) Histology 0.130DCIS189 (21.8%)223 (21.2%) IDC531 (61.3%)688 (65.3%) ILC113 (13.1%)99 (9.4%) Other33 (3.8%)43 (4.1%) LVI127 (14.7%)174 (16.5%) Multifocality147 (17%)183 (17.4%) Median tumor size (cm; range)1.4 (0-9.5)1.3 (0-12.5)0.489Estrogen Receptor 0.206Positive726 (84.7%)861 (82.6%) Negative131 (15.3%)182 (17.4%) Progesterone Receptor 0.275Positive621 (72.5%)732 (70.2%) Negative236 (27.5%)311 (29.8%) HER2/neu Receptor 0.068Positive78 (12%)121 (15.4%) Negative571 (88%)667 (84.6%)
Conclusions: Breastfeeding experience was not generally associated with significant differences in tumor or patient characteristics. However, breastfeeding for longer than 12 months was associated with LVI. It is possible that changes in the breast tissue that occur during the process of pregnancy and prolonged lactation may influence future tumor development. These findings are hypothesis generating and suggest that the relationship of prolonged breastfeeding and breast cancer development should be investigated further.
Citation Format: Gooch JC, Chun J, Jubas T, Guth A, Schnabel F. Breastfeeding experience among breast cancer patients in the modern era [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P4-10-07.