Fig. 4

The relationship between treatment characteristics and recurrence rates in breast cancer patients with healthy weight vs obesity defined by BMI. Forest plot shows adjusted HR (95% CI) of breast cancer recurrence for patients with obesity (BMI ≥ 30.0) compared with patients with healthy weight (BMI 18.5–24.9), according to stratified treatment characteristics. *BCR = breast cancer recurrence. ** The stratified analyses were adjusted for the following co-variables excluding the stratified variable of interest: age, histological grade, tumor size, nodal status, estrogen-receptor status, surgery, planned adjuvant radio-, chemo-, and endocrine therapy. ***The relative excess risk due to interaction with 95% CI for chemotherapy in patients with obesity was 1.21 (0.95–3.37) indicating a super-additive interaction effect, suggesting that the response to these exposures combined is greater than the sum of the independent responses to chemotherapy and obesity alone