Abstract P4-11-32: Change in body mass index in breast cancer survivors
Authors: Abu-Khalaf Maysa , Nikita Fnu , Shimada Ayako , Hackbart Hannah , Alnabulsi Dina , Keith Scott , Lopez Ana Maria , Butryn Meghan 
Published: March 2022

Background: Obesity is associated with an increased risk of breast cancer recurrence and poor survival. Obesity rate in adults in the city of Philadelphia is high, with non-Hispanic blacks and Hispanics having the highest rates. We sought to evaluate changes in body mass index (BMI) in breast cancer survivors within the first 2 years from initial encounter for a breast cancer (BC) diagnosis (dx), and investigate factors that may correlate with a change in BMI. Methods: We identified 5,423 BC patients (pts) in our electronic medical record, (1/2015-present), using ICD-10 code C50.X. We then selected pts with BMI values at the three-time points: baseline, 1 year and 2 year intervals from baseline. The closest BMI value before the 1st encounter within 6 months prior to BC dx was considered as the baseline BMI. BMI at 1 year +/- 3 months after the BC dx was considered 1-year interval BMI. BMI at 2 years +/- 6 months after the BC dx was considered 2-year interval BMI. Subjects needed baseline BMI and at least 1 year or 2 year follow-up BMI for inclusion. After all BMI exclusions, 630 pts were included in the study cohort. We used a mixed effects model to predict BMI changes as a linear function of association with time, sex, race and ethnicity, age at BC dx, baseline BMI, treatments (i.e., chemotherapy [CT], endocrine therapy [ET], or immunotherapy [IO] and the interaction of race and ethnicity and treatment in estimating mean change of BMI. The significance level of all tests was set a priori to the 0.05 level. Results: The mean age at BC dx was 61 years; pts identified were mostly white, non-Hispanic/Caucasian (55%), or Black/African American (AA) (34%). By BMI category, we did not observe any substantial difference in the mean age at BC dx and gender distribution (p = 0.81 for age and p = 0.86 for gender). However, the distributions of race and ethnicity differed among BMI categories (p &lt; .01) where the percentage of Black/AA pts was high in the BMI ≥ 30 category. Black/AA pts receiving IO were likely to have BMI change (decrease) compare to white non-Hispanic pts with similar conditions. Black/AA pts receiving no treatment or non IO-treatment were more likely to change BMI (increased, 95% CI: 0.22, 1.03) after BC dx compared to white, non-Hispanic pts. Interestingly, Black/AA pts receiving IO tended to change BMI (decreased) compared to Black/AA pts not receiving IO. Conclusion: We observed the interaction effect of race/ethnicity and treatment on BMI change in BC survivors within 2 years after a BC dx, with Black/AA pts more likely to have an increase in BMI.

Table 1.Descriptive Statistics Summary, n = 630.VariableALL (n=630)BMI ≤ 24.9 (n=160, 25%)25 ≤ BMI ≤ 29.9 (n=180, 29%)BMI ≥ 30 (n=290, 46%)p-valueAge at 1st Encounter with BC dx, mean (SD)61.8 (11.8)62.1 (12.5)62.1 (12.1)61.5 (11.2)0.808Sex, n (%)Female625 (99.2)159 (99.4)178 (98.9)288 (99.3)0.857Male5 (0.8)1 (0.6)2 (1.1)2 (0.7)Race & Ethnicity, n (%)White/Caucasian348 (55.2)103 (64.4)106 (58.9)139 (47.9)&lt;.001Black/AA215 (34.1)35 (21.9)48 (26.7)132 (45.5)Hispanic/Latino20 (3.2)5 (3.1)5 (2.8)10 (3.4)Asian/Pacific Islander39 (6.2)17 (10.6)18 (10.0)4 (1.4)American Indian/Alaskan Native2 (0.3)0 (0.0)0 (0.0)2 (0.7)Unknown6 (1.0)0 (0.0)3 (1.7)3 (1.0)BMI (baseline), mean (SD)29.9 (7.1)22.2 (2.0)27.1 (1.4)35.9 (5.7)&lt;.001Treatment (Yes) , n (%)HistoricalCT2 (0.3)1 (0.6)1 (0.6)0 (0.0)0.294ET35 (5.6)7 (4.4)12 (6.7)16 (5.5)0.663IO4 (0.6)2 (1.3)1 (0.6)1 (0.3)0.487BaselineCT20 (3.2)4 (2.5)7 (3.9)9 (3.1)0.815ET54 (8.6)16 (10.0)15 (8.3)23 (7.9)0.742IO11 (1.7)5 (3.1)2 (1.1)4 (1.4)0.3111 yearCT154 (24.4)41 (25.6)42 (23.3)71 (24.5)0.886ET309 (49.0)73 (45.6)93 (51.7)143 (49.3)0.535IO29 (4.6)10 (6.3)8 (4.4)11 (3.8)0.4892 yearsCT71 (11.3)20 (12.5)15 (8.3)36 (12.4)0.337ET231 (36.7)50 (31.3)73 (40.6)108 (37.2)0.198IO32 (5.1)7 (4.4)4 (2.2)21 (7.2)0.051

Citation Format: Maysa Abu-Khalaf, Fnu Nikita, Ayako Shimada, Hannah Hackbart, Dina Alnabulsi, Scott Keith, Ana Maria Lopez, Meghan Butryn. Change in body mass index in breast cancer survivors [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 P4-11-32.