Food consumption according to degree of processing and risk of breast cancer: prospective findings from the Moli-sani Study cohort.

BACKGROUND

The potential impact of food processing on breast cancer (BC) has not been extensively addressed.

OBJECTIVES

This study sought to examine the association of food consumption according to the Nova classification with BC incidence in a large cohort of Italian females.

METHODS

Longitudinal analyses were conducted on 11,442 cancer-free females recruited in the Moli-sani Study (2005‒2010). Food intake was assessed at baseline using a 188-item food frequency questionnaire, and categorized into 4 mutually exclusive groups based on the extent and purpose of processing according to the Nova classification: 1) unprocessed/minimally processed foods; 2) processed culinary ingredients; 3) processed foods; and ultraprocessed foods. Each Nova group was expressed as its proportion (grams per day) of total food eaten (grams per day). Incident BC cases were ascertained by direct linkage with hospital discharge forms and validated through medical records. Associations between dietary exposures and BC outcomes were assessed using multivariable cause-specific Cox proportional hazard models controlled for known risk factors.

RESULTS

Over a median follow-up of 13.1 y (146,522 person-years), 295 BC cases were recorded. Multivariable-adjusted hazard ratios (HRs) for overall BC risk associated with highest compared with lowest quartile of consumption of unprocessed/minimally processed foods, culinary ingredients, processed food, and ultraprocessed foods were 1.10 [95% confidence interval (CI): 0.75, 1.59], 1.03 (95% CI: 0.74, 1.44), 1.55 (95% CI: 1.10, 2.17), and 1.04 (95% CI: 0.72, 1.51), respectively. When alcoholic beverages were removed from processed foods, the associated HR was 0.94 (95% CI: 0.67, 1.33) for quartile 4 compared with quartile 1. Food processing was not associated with BC subtypes, including menopausal status and hormone receptor status.

CONCLUSIONS

In this cohort of Italian females, food consumption based on the degree of processing was not associated with BC incidence. Although a higher intake of processed foods appeared linked to increased risk, this was largely explained by alcoholic beverages. These findings are in agreement with previous research, which overall remains inconclusive about the link between food processing and BC.