Abstract
While many studies have evaluated the relationship between BMI and breast cancer outcomes, it is unclear whether this relationship is consistent between early breast cancer (BC) and advanced BC. The study included 5099 patients with HER2 positive early BC (EBC) and 3496 with HER2 positive advanced BC (ABC). In the EBC cohort, higher BMI was associated with worse overall survival (OS) (HR [95% CI]: overweight = 1.30 [1.13–1.51]; obese = 1.37 [1.14–1.64], P = < 0.001), and worse disease-free survival (overweight = 1.10 [0.98–1.24]; obese = 1.20 [1.04–1.39], P = 0.061). In contrast, for the ABC cohort, higher BMI was significantly associated with improved OS (overweight = 0.85 [0.76–0.96]; obese = 0.82 [0.72–0.95], P = 0.014), and progression-free survival (overweight = 0.91 [0.83–1.01]; obese = 0.87 [0.77–0.98], P = 0.034). In this large high-quality dataset, higher BMI was independently associated with worse survival in EBC, paradoxically in ABC higher BMI was independently associated with improved survival.
Highlights
Higher body mass index (BMI) is associated with an increased risk of developing many types of cancer including human epidermal growth receptor 2 (HER2) positive breast cancer (BC)[1,2]. This is a result of elevated levels of circulating sex hormones, high serum leptin, and chronic inflammation that are associated with high BMI and high adiposity, which contribute to an increased risk of developing BC3,4
Results have been conflicting with respect to whether a paradox exists in ABC30,32, some studies showing no association with BMI30,31,34,35, and others finding that higher BMI is associated with poorer outcomes[26,27,28,29]
Data was available for 5099 HER2 positive early breast cancer (EBC) patients, of which 102 (2%) were underweight, 2433 (48%) normal weight, 1689 (33%) overweight, and 836 (16%) obese (Supplementary Table 1)
Summary
Higher body mass index (BMI) is associated with an increased risk of developing many types of cancer including human epidermal growth receptor 2 (HER2) positive breast cancer (BC)[1,2]. Results have been conflicting with respect to whether a paradox exists in ABC30,32, some studies showing no association with BMI30,31,34,35, and others finding that higher BMI is associated with poorer outcomes[26,27,28,29] Owing to these conflicts[26,30,31,32], as well as the known heterogeneity in the association between BMI and survival according to BC subtypes and treatment in EBC6, there is a need to establish the relationship between BMI and survival in HER2 positive ABC and HER2 positive EBC in patients receiving contemporary treatment options. This study, aimed to determine the association between BMI and survival outcomes according to HER2 positive BC status (early vs. advanced)
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