Abstract P3-12-07: Breast cancers are overrepresented in school teachers, particularly of young students
Authors: Jonathan Gagnon, Meredith H. Wernick
Journal: Cancer Research (2022)

Abstract Introduction:. Higher breast cancer risks among California teachers1 and school employees2 have been documented in mortality studies and a large cohort study, the California Teacher’s Study (CTS).3 Reasons for the risk are only partially explained by known risk factors, and predictive models such as the Rosner-Colditz and Gail model explain only a part of the risk in the CTS.4 Here we analyze data from the State of Virginia Tumor Registry on 394,837 female cancer cases diagnosed from 1995-2018 to explore breast cancer risk in teachers and to generate hypotheses on the etiology of this risk. Methods:. Data on 394,837 female cancer patients from the State of Virginia Cancer Registry were evaluated. Cancer diagnoses were available in all, but occupational data was incomplete; 219,807 were listed as unknown, 18,123 unemployed, 32,714 retired. Among employed cases, 16,001 were homemakers, 14,306 employed in teaching or related school occupations, and 93,921 were employed in non-teaching occupations. The data allowed subdividing of teachers into K-Elementary, Middle-High School, and teachers NOS. School system employees were also evaluated. Registered Nurses (RNs) were used as a comparison group, given similar education levels with teachers. Comparisons were made using Pearson’s Χ2 with Yates correction. Results:. Among all cancer diagnoses, breast cancers were diagnosed in 28.06% of the unemployed, 29.50% of retirees, 30.96% of homemakers, 39.23% of employed non-teachers, and 44.30% of teachers (for teachers vs. employed non-teachers Χ2=52.45, p&amp;lt;.000001). 336 of 869 RNs (38.67%) had breast cancers, statistically lower than teachers (Χ2=24.28, p&amp;lt;.000001). Subdividing teachers by teaching grades showed that 47.7% (555/1163) of K-Elementary teachers, 42.8% (549/1282) of Middle-High School teachers, 43.9% (3832/8731) of teachers-NOS, and 42.0% (224/533) of school system employees in the database had breast cancers. K-Elementary teachers had proportionally more breast cancers than Middle-High School teachers (Χ2=5.71, p&amp;lt;.02), or teachers-NOS (Χ2=5.95, p&amp;lt;.02). Middle-High School teacher rates did not differ significantly from teacher-NOS (Χ2=.47, p=.49) or school system employees (Χ2=.07, p=.79). Discussion:. This study confirms a highly statistically significant overrepresentation of breast cancer in school teachers compared with other occupations and compared with the subgroup of RNs, a similarly educated group. Interestingly, teachers of young children have a higher risk than other teachers. Hypotheses concerning these findings, in addition to workplace exposures or correlations between selection of a teaching career and breast cancer risk, might include higher levels of endogenous estrogen or oxytocin in teachers, possibly promoting breast cancer development.5 We note that mutations of the oxytocin or oxytocin receptor genes are identified in 18% of breast cancers in the TCGA NIH database.6 Curiously, ovarian and endometrial cancers also have frequent mutations of oxytocin or its receptor in this database (42% and 17%), and these two epithelial cancers are also found in excess in the CTS.3 Although the role of oxytocin in malignancy is unclear,5 elevated plasma oxytocin levels have been found in breast cancer patients compared to healthy individuals.7. 1 Reidmiller K, Doebbert G, Glazer E (1987) California Occupational Mortality 1979-1981.2 Reynolds P, Elkin EP, Layefsky ME. Am J Ind Med 1999;36:271-278.3 Bernstein L, Allen M, Ross RK. Cancer Causes and Control 2002;13:625-635.4 Rosner BA, Colditz GA, Bernstein L. Breast Cancer Res Treat 2913;142:187-202.5 Liu H, Gruber CW, Muttenthaler M. Oncogene 2020;39:5917-5932.6 https://portal.gdc.cancer.gov/7 Ariana M, Pornour M, Akbari M. Per Med 2018;16:25-34. Citation Format: Jonathan Gagnon, Meredith H. Wernick. Breast cancers are overrepresented in school teachers, particularly of young students [abstract]. In: Proceedings of the 2021 San Antonio Breast Cancer Symposium; 2021 Dec 7-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2022;82(4 Suppl):Abstract nr P3-12-07.