Metabolic syndrome as a risk factor for the development of breast cancer in women and its impact on prognosis

Abstract

Objective: Metabolic syndrome (MS) is a complex metabolic disorder. The aforementioned main components are systemic
arterial hypertension, insulin resistance, obesity, and dyslipidemia. Highly acclaimed evidence supports the hypothesis
that MS may be associated with breast cancer (BC) development and worse prognosis. The increasing incidence rates of
both MS and BC seem to corroborate this theory. This article aims to assess the association between MS and BC development, later diagnosis, and worse prognosis. Methodology: An inclusive literature review was conducted on PubMed and
SciELO. Results: First, excess of adipose tissue characteristic of MS not only enhances the expression of pro-inflammatory factors but also increases the aromatization process. The latter is a neuroendocrine change that occurs in adipocytes
and leads to greater estrogen synthesis, which increases the risk for the development of BC. It was concluded that MS is
an independent risk factor for BC with a relative risk (RR) of 1.75%. MS is also associated with more aggressive and poorer
differentiated tumors. Women with MS have higher rates of BC in stages III and IV. Furthermore, hyperinsulinemia and
hyperglycemia are directly related to axillary lymph node involvement, high histological grade, and late staging. Moreover,
it is known that women diagnosed with both MS and BC have worse oncologic prognosis. The aforesaid is exemplified by
the increased recurrences and decreased survival in BC associated with high fasting plasma insulin levels. Additionally,
obese women with BC have a worse prognosis and a higher risk of developing a second primary BC. Conclusion: As mentioned above, MS is significantly associated with an increased risk, invasive progression, and adverse outcomes of BC due
to neuroendocrine changes, namely, abnormal estrogen levels. It is therefore strongly recommended to adhere to dietary
strategies and regular physical activities in order to prevent MS. Consequently, there would be a possibility of reducing
the incidence rates of BC.