Perda de força muscular do assoalho pélvico em portadoras de câncer de mama e mecanismos moleculares associados

Abstract

Breast cancer is the neoplasm that most affects women worldwide, in both developed and developing countries. Among the risk factors are hereditary, genetic, and environmental factors, with exposure to pesticides being correlated with an increased probability of disease development. Due to its inflammatory and systemic nature, survivors may develop new diseases or dysfunctions. Evidence demonstrates that breast cancer patients present loss of muscle strength, including that of the pelvic floor (PF). Pro-inflammatory mediators such as tumor necrosis factor alpha (TNF-α) and oxidative stress metabolites participate in the molecular mechanisms associated with this loss. Although there is no direct established correlation between elevated levels of pro-inflammatory cytokines and specific weakness of PF muscles, it is plausible that similar mechanisms affect this musculature given its composition and function. Thus, the objective of this study was to characterize pelvic floor muscle strength in breast cancer patients and investigate the clinical profile and associated molecular markers. The sample consisted of a total of 122 participants with infiltrating ductal carcinoma (IDC) treated at the 8th Regional Health Unit of Paraná – Brazil. After collecting sociodemographic data, clinical and gynecological data, and occupational pesticide exposure, pelvic floor muscle strength was measured through perineometry tests, with reference values between 0 and 46.4 mmHg, and bidigital palpation through pelvic floor assessment (PFA) with a scale between 0 and 5. Plasma levels of TNF-α and oxidative stress levels were quantified through lipoperoxide measurements by high sensitivity chemiluminescence, as well as levels of nitric oxide metabolites (NOx). Quantitative variables were evaluated with appropriate statistical tests, using GraphPad Prism 9.0, RStudio, and SPSS software, and p-values below 0.05 were considered statistically significant. Pelvic floor muscle strength of 73.8% of women was classified as mild to moderate through perineometry, and 61.5% of women had weak and non-resistant perineal function through PFA. A negative correlation was observed between perineometry values and TNF-α and NOx, indicating worse pelvic floor muscle conditions with increased levels of these inflammatory markers (p=2.06e-07 and p=1.700e-02). A significant correlation was also identified between PFA and the patients' pesticide exposure profile (p=0.0223), as well as a significant negative correlation with perineometry (p=0.0404). The group exposed to pesticides (n=66) presented lower perineometry values (95% CI: 0.007-0.409). Significant differences were also found between patients with unsatisfactory PFA and perineometry results with elevated TNF-α values, suggesting that this cytokine may be a mediator of pelvic floor strength loss in breast cancer (p=0.0001).