Relationship Between Serum Vitamin D Levels, Body Adiposity, and Muscle Strength in Women with Breast Cancer
Name: MARIA RITA PEREIRA DA SILVA GARCIA RAFALSKY
Publication date: 30/08/2024
Examining board:
Name |
Role |
|---|---|
| FABIOLA LACERDA PIRES SOARES | Examinador Interno |
| JOSE LUIZ MARQUES ROCHA | Coorientador |
| MARIA CLAUDIA BERNARDES SPEXOTO | Examinador Externo |
| VALDETE REGINA GUANDALINI | Presidente |
Summary: Breast cancer (BC) is the most prevalent type of cancer among women in Brazil and worldwide. Among the changes in body composition, fat mass gain and impaired muscle mass and strength are common. Body adiposity has been associated with low vitamin D levels in several populations. In women with BC, vitamin D deficiency may be even more harmful due to its functions in regulating calcium homeostasis, oncoprotective properties, and influence on muscle tissue and muscle strength (MS). This study had the following objectives: 1) To investigate the association between fat mass index (FMI) and serum vitamin D levels in women diagnosed with BC; 2) To analyze the relationship between serum vitamin D levels and MS. This is a cross-sectional, observational, and non-probabilistic study, conducted between January 2021 and August 2024, with adult women diagnosed with BC for up to 12 months, treated at a mastology outpatient clinic of a university hospital. Sociodemographic, clinical, lifestyle, body composition, anthropometric and biochemical data were collected. Body composition was assessed by dual-energy X-ray absorptiometry (DXA). The variables were described by measures of central tendency and dispersion for continuous variables and percentages for categorical variables. The normality of the variables was verified by the Kolmogorov-Smirnov test. Fisher's exact and partitioned chi-square tests were used to compare proportions and the ANOVA and Kruskal-Wallis tests were used to analyze differences when the variables were continuous. Multinomial logistic regression models were used to investigate the association between FMI and vitamin D levels (manuscript 1), considering vitamin D sufficiency as a reference, and to evaluate the association between vitamin D levels and FM (manuscript 2), considering the third tertile of strength as a reference. The significance level adopted was 5% for all tests, and the analyses were performed using SPSS, version 26.0, and STATA®, version 16.0. In the first manuscript, 135 women were evaluated. Of these, 66.7% were adults, 65.2% self-declared as black or brown, 59.3% were insufficiently active, 76.1% did not consume alcoholic beverages, and 94.1% did not smoke. Regarding vitamin D, 17.8% had deficiency, 57.8% insufficiency, and 24.4% sufficient levels. Most women had a diagnosis 6 months (83.3%), invasive breast carcinoma (71.9%), positive hormone receptor (85.0%), luminal B molecular subtype (50.5%), and stage IIA/IIB (46.3%). The mean FMI value was 12.2±3.7 kg/m², classified as high. Significant differences were found between serum vitamin D levels and BMI, body fat percentage (BF%), visceral abdominal fat (VAF), FMI and appendicular skeletal muscle mass index (ASMI) (p<0.05). FMI was associated with vitamin D insufficiency (OR: 2.26, 95% CI: 1.38–3.72, p=0.001) and vitamin D deficiency (OR: 2.21, 95% CI: 1.26–3.91, p=0.006). In manuscript 2, 151 women were evaluated. Of these, 67.5% were adults, 66.9% self-declared as black/brown, 58.9% were insufficiently active, 81.3% did not consume alcoholic beverages and 96.6% did not smoke. 84.4% had a time since diagnosis 6 months (82.4%), invasive breast carcinoma (67.8%), luminal B molecular subtype (47.3%) and stage IIA/IIB (47.8%). Most women were overweight (70.2%) and had insufficient levels of vitamin D (69.5%). Insufficient serum vitamin D levels were associated with the 1st and 2nd tertile of FM (OR: 5.74, 95% CI: 1.77–18.64, p=0.004; OR: 4.48, 95% CI: 1.34–14.97, p=0.015, respectively).
