Abstract C088: Assessing vitamin D and mammographic breast density in a population of Alaskan Native women
Authors: Duma Narjust , Croghan Ivana , Jenkins Sarah , Neal Loni , Ghosh Karthik , Pruthi Sandhya 
Published: August 2020

Background: Several studies have suggested that vitamin D may have antiproliferative and anticarcinogenic properties and a protective effect against breast cancer. Alaskan Natives have demonstrated high rates of vitamin D deficiency, particularly in young individuals. Hence, high breast density has been associated with increased breast cancer risk. Therefore, we examined the association between serum vitamin D levels and mammographic breast density in a population of Alaskan Native women.

Methods: Patients seen in the Mayo Clinic-Alaska Native Medical Center telemedicine program from December 2014 to December 2017 were offered to enroll in the study. Consent was obtained by a study coordinator in Minnesota using a telemedicine platform. Participants were asked to complete the Breast Cancer Risk Questionnaire, which includes questions on hormonal, lifestyle factors and family history. Serum vitamin D levels (25-hydroxyvitamin D2 and D3) were obtained and later correlated with mammographic breast density (percent density). Data were summarized with frequencies and percentages or medians and interquartile ranges (IQR), as appropriate. Pearson correlation was used to estimate the association between breast density and vitamin D levels.

Results: 33 women were included; median age was 53 years (IQR 45-58), 70% self-identified as American Indian/Alaskan Native, 12% as White, 6% as Native Hawaiian/Pacific islander and 12% as other. Median BMI was 31 kg/m² (IQR 26.4-34.3), menarche was at age 12 or older for 23 (70%) of the participants and 20 women were postmenopausal at the time enrollment. 10 participants had a hysterectomy, of whom 60% also had oophorectomy. 76% reported history of hormonal birth control use and 23% postmenopausal hormonal supplementation. Median number of pregnancies was 3 (IQR 2-5), and 20 women reported breastfeeding. Fifteen women were current or former smokers (&gt;100 cigarettes) and 19 reported none or low alcohol consumption. Median serum vitamin D level was 39 ng/mL (IQR 30-52) and 9 (27%) women had low vitamin D levels. In regard to breast density, median percentage (average of images) was 15% (IQR 7.5-24.9) with a median dense area of 21.8 cm² (IQR 16.4-34.2). Median time from blood draw to mammogram was 110 days (IQR 41-172) and 19 (58%) participants were taking vitamin D supplementation at the time of study enrollment; doses ranged from 400 to 50,000 units. No correlation was identified between breast density and serum vitamin D levels (correlation=0.02).

Conclusion: In this cohort, no association between serum vitamin D levels and breast density was observed. More than half of the participants were on vitamin D supplementation and this could have obscured our observations. Larger studies controlling for vitamin supplementation are needed, as this association could potentially impact breast cancer rates in populations at risk for vitamin D deficiency.

Citation Format: Narjust Duma, Ivana Croghan, Sarah Jenkins, Loni Neal, Karthik Ghosh, Sandhya Pruthi. Assessing vitamin D and mammographic breast density in a population of Alaskan Native women [abstract]. In: Proceedings of the Eleventh AACR Conference on the Science of Cancer Health Disparities in Racial/Ethnic Minorities and the Medically Underserved; 2018 Nov 2-5; New Orleans, LA. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2020;29(6 Suppl):Abstract nr C088.