Interplay Between Western Diet and Mammary Cancer: Data from a Chemically-induced Model in Wistar Rats.

Background/aim: This study aimed to investigate the influence of Western diet on mammary cancer in Wistar female rats, focusing on systemic responses and tumor development.

Materials and methods: Twenty-eight Wistar female rats were acclimatized and divided into four experimental groups (n=7 each): Western diet (WD), Western diet with N-methyl-N-nitrosourea (MNU) administration (WD+MNU), standard diet (CTR), and standard diet with MNU administration (CTR+MNU). MNU was administered intraperitoneally at 50 mg/kg at seven weeks of age to induce mammary cancer. The 20-week experiment involved monitoring animal weight, food and water intake. At the end of the study, rats were euthanized, and blood samples and organs were collected for hematological and plasma biochemical analysis, oxidative stress, and histo-pathological and immunobiological evaluations of the tumors.

Results: No significant differences were found in body weight, composition, or organ weights, but the WD group showed reduced food and water intake and lower cholesterol levels. Leptin and adiponectin levels were higher in the WD+MNU group, suggestive of changes in appetite regulation. Histopathological analysis showed malignant tumors in both MNU-induced groups. However, WD groups had fewer tumors compared to the CTR+MNU group.

Conclusion: WD led to higher feed efficiency and increased visceral adipose tissue but decreased systemic cholesterol and triglyceride levels. While this diet resulted in lower tumor incidence, the volume and weight of the tumors were higher. Additionally, the WD decreased ERα and progesterone receptor immunoexpression, while Ki-67 immunoexpression was elevated.