Obesity-associated Breast Inflammation among Hispanic/Latina Breast Cancer Patients

Abstract

Breast white adipose tissue inflammation (BWATi) is associated with obesity and higher breast cancer risk among non-Hispanic white women. Obesity is prevalent in Hispanic/Latina patients with breast cancer, and the occurrence of BWATi in this population is not well-characterized. The association between BWATi and body mass index (BMI) was evaluated in Hispanic/Latina patients with breast cancer who underwent mastectomy. BWATi was defined as the presence of crown-like structures of the breast (CLS-B), detected by CD68 IHC in nontumor breast tissue. BWATi severity was quantified as number of CLS-B/cm² Adipocyte diameter was measured using hematoxylin and eosin-stained breast tissue sections. Preoperative BMI (within 1 week prior to mastectomy) was categorized as normal (18.5-<25.0 kg/m²), overweight (25.0-<30.0 kg/m²), class I obesity (30.0-<35.0 kg/m²), and class II-III obesity (35.0 kg/m² or above). Patient charts were abstracted to record clinicopathologic features and liver function tests <90 days before mastectomy. The study included 91 women (mean age 69 years; range 36-96 years). Prevalence of BWATi increased with BMI (24% in normal weight, 34% in overweight, 57% in class I obesity, and 65% in class II-III obesity; P _trend <0.01). Severe BWATi (>0.27 CLS-B/cm²) was associated with higher BMI (P _trend = 0.046) and greater adipocyte diameter (P = 0.04). Adjusting for BMI, neoadjuvant chemotherapy, and elevated alanine aminotransferase were associated with severe BWATi, and current smoking was associated with mild BWATi (all P < 0.05). BWATi was associated with higher BMI in Hispanic/Latina patients with breast cancer, consistent with previously described associations in other populations.

Figure 1.. Breast white adipose tissue inflammation by BMI category (n=91).

Figure 1A shows the prevalence of CLS-B by BMI category, and Figure 1B shows the distribution of mild and severe inflammation by BMI category. In Figure 1B, inflammation severity is defined categorically as follows and using median number of CLS-B/cm² (0.27) as the cutoff: no inflammation (CLS-B absent), mild inflammation (≤0.27 CLS-B/cm²), and severe inflammation (>0.27 CLS-B/cm²).

Figure 2.. Association between average adipocyte diameter and biomarkers of liver function.

The box plots compare the mean adipocyte diameters between groups, and the scatter plots and fitted linear regression lines show the correlation between mean adipocyte diameter and each biomarker. Patients with higher BMI and more severe breast WAT inflammation had larger adipocyte diameter (all P<0.05). For box plots, statistically significant differences between groups were denoted by *: P<0.05, **: P<0.01, ***: P<0.001, and NS: not significant. Abbreviations: BMI, body mass index; CLS-B, crown-like structure of the breast; ALT, alanine aminotransferase; AST, aspartate aminotransferase.

Figure 3.. Biomarkers of liver function by presence of CLS-B (Figure 3A) and severity of breast white adipose tissue inflammation (Figure 3B).

The boxplot shows the median (dark horizontal line inside box), the 25% percentile (lower bound of box), and the 75% percentile (upper bound of box) of each biomarker by inflammation status. The horizontal bar with a star denotes statistically significant differences between groups. Patients with severe breast WAT inflammation had higher ALT compared to patients with mild (P=0.02) or no breast WAT inflammation (P=0.01). Patients with severe breast WAT inflammation had higher AST compared to patients with mild breast WAT inflammation (P=0.03). Abbreviations: CLS-B, crown-like structure of the breast; ALT, alanine aminotransferase; AST, aspartate aminotransferase.