Body Composition as a Biomarker for Disease Recurrence in Patients with Triple Negative Breast Cancer

Purpose/Objective(s)

Obesity is associated with a higher risk of hormone receptor-positive breast cancer, disease stage, grade, and poor disease outcome. The effect of obesity in triple negative breast cancer (TNBC), as well as its effect on patients undergoing radiation, is less well studied. Body Mass Index (BMI) is used as a crude measure for obesity but does not reliably detect patients with high visceral fat which is associated with inflammation and angiogenesis that drives the development and progression of cancer. The purpose of this study was to evaluate the feasibility of using semi-automated measures of visceral-to-subcutaneous fat ratio (VSR) for risk stratification in TNBC patients undergoing radiation.

Materials/Methods

This retrospective analysis included 56 women who received radiation for stage II-III TNBC. Patients included in this study were followed for at least 5 years or until disease progression (DP). Baseline characteristics including age, clinical stage, T-stage, grade, and BMI were collected. Waist circumference and VSR were obtained using a semi-automatic freely available segmentation software tool with demonstrated reproducibility. Computed Tomography (CT) images at the level of lumbar spine L2-L3 were used for this analysis because prior studies have shown that measures performed at this level have the least intra-patient variability. BMI, waist circumference, and VSR were assessed in both patients with and without DP.

Results

Of the 56 patients, 34 presented with stage II disease. Mean age was 51 ± 13 years. Mean follow-up after radiation was 88 ± 53 months. Mean time from CT scan to radiation was 12 ± 142 days. BMI, waist circumference, or VSR was not significantly different between clinical stage, T-stage, or grade. Of the 56 patients, 25 had DP, and 14 of these patients initially presented with clinical stage III disease. In patients with DP, BMI was similar (31.9 ± 8.0 kg/ m² vs. 31.1 ± 7.0 kg/ m²) while there was an increasing trend in VSR (64.4 ± 39.6% vs. 51.5 ± 22.5%). Waist circumference was lower in patients with DP (100.9 ± 17.3 cm vs. 107.8 ± 21.9 cm).

Conclusion

With this work, we demonstrated the feasibility of using a semi-automated software tool to evaluate body fat compartments. In this small cohort of TNBC patients, we established a trend toward higher VSR in patients with DP, and our data suggest that VSR has more discriminatory power to risk stratify patients with TNBC than BMI. Waist circumference, on the other hand, seems less reliable as it contradicts prior studies utilizing BMI as a risk stratifier. Corroborating our findings in a larger cohort of patients is of importance as it may have implications for trials investigating lifestyle modifications in TNBC patients, or for trials evaluating adaptive radiation based upon risk stratification. Our future efforts will focus on accruing more patients to further establish the relationship between body fat compartments, inflammation, and disease progression.