Dietary patterns, nutrition, and risk of breast cancer: a case-control study in the west of Iran

Abstract

Objectives: Unhealthy dietary patterns are the most important changeable risk factors for breast cancer. The aim of this study was to assess the relationship between dietary patterns and the risk of breast cancer among under-50 year women in the west of Iran.

Methods: All women under 50 years old with pathologically confirmed breast cancer between 2013 and 2015 who were referred to oncology clinics in the west of Iran, and 408 under-50 women referred to other outpatient clinics who were without breast or other cancers at the time of the study and 2 years later were selected as the control group. The data were collected using the middle-aged periodical care form of the Iranian Ministry of Health and analyzed using univariate and multivariate logistic regression in Stata.

Results: The most powerful risk factor for breast cancer was fried foods; the odds ratio of consuming fried foods more than once a month for breast cancer was 4.5 (95% confidence interval, 2.1 to 9.4). A dose-response model indicated that increasing vegetable and fruit consumption up to 90 servings per month decreased the odds of breast cancer, but consuming more than 90 servings per month increased the risk.

Conclusions: Inadequate consumption of vegetables and consumption of soft drinks, industrially produced juices, fried foods, and sweets were identified as risk factors for breast cancer. In response to these findings, it is necessary to raise awareness and to provide education about healthy diets and the need to change unhealthy dietary patterns.

Keywords: Breast cancer; Case-control studies; Diet; Iran.

Figure 1.

Flowchart of the research process.

Figure 2.

Dose-response relationships of (A) fast food, (B) fried foods, (C) sweets, and (D) soft drinks in terms of the frequency of consumption per month with the odds of breast cancer based on fractional polynomials adjusted for demographic variables including age, gender, education level, and body mass index.

Figure 3.

The odds of breast cancer associated with the consumption of (A) dairy products, (B) fats and oils, (C) vegetables, and (D) fruits in terms of the frequency of consumption per month.