Salad vegetables dietary pattern protects against HER‐2‐positive breast cancer: A prospective Italian study

Abstract

Studies investigating the relation of diet to breast cancer have produced conflicting results. We hypothesized that dietary factors associated with breast cancer risk might differentially influence the HER-2 status of the cancers that develop, and investigated this hypothesis by analyzing the data of the ORDET prospective study. We analyzed 8,861 volunteer women residents of the Varese Province, Italy, for whom we had full data. By December 31, 2001, 238 cases had occurred in which HER-2 status was known. Four dietary patterns had been identified previously by factor analysis: salad vegetables (high consumption of raw vegetables and olive oil), prudent (cooked vegetables, poultry, fish), western (potatoes, meat, eggs, butter), and canteen (pasta, tomato sauce, wine). In our study, relative risks (RRs) of developing HER-2-positive and HER-2-negative breast cancers by tertiles of dietary pattern factor scores were assessed by multinomial logistic regression. The salad vegetables dietary pattern had a protective effect against HER-2-positive cancers (RR 5 0.25, 95% CI 0.10-0.64, for the highest tertile; p trend 5 0.001), much stronger than for HER-2-negative cancers (p heterogeneity 5 0.039). This important finding that a salad vegetables dietary pattern protects mainly against a specific breast cancer subtype indicates that future studies on environmental/dietary risk factors should explicitly take account of the heterogeneity of breast cancer phenotypes. ' 2007 Wiley-Liss, Inc.Key words: breast cancer; dietary pattern; HER-2The incidence of breast cancer varies markedly between countries, suggesting that dietary habits might be an important cause of this variation. A recent analysis of the ORDET (Hormones and Diet in Etiology of Tumors) cohort suggested that a dietary pattern characterized by high consumption of raw vegetables and olive oil may reduce breast cancer risk, especially in lean women (BMI < 25). 1 Other studies of dietary pattern have not shown such an association, 2 and epidemiologic studies on vegetable consumption and breast cancer have not provided clear results. 3,4 Etiological relationships between diet and breast cancer may have been masked by lack of consideration of cancer phenotype. Only a few studies have investigated associations between risk factors and cancer phenotype, most of which investigated the expression of receptors for estrogen and progesterone. 5-7 Studies considering HER-2 overexpression, which confers aggressivity [8][9][10] and is usually associated with an estrogen receptor-negative phenotype, 11 have been carried out mainly to investigate the relation of HER-2 overexpression to prognosis and response to treatment. 12 The relationship between etiologic risk factors and HER-2 overexpression has not been extensively investigated. It has been suggested that HER-2 overexpression bears little relation to the classic reproductive risk factors for breast cancer. 13 It is unclear, however, whether dietary factors can influence the biological characteristics of breast cancers, and t...

Dietary patterns and breast or lung cancer risk: A pooled analysis of 2 case-control studies in north-eastern Poland

“…Many studies performed in different countries such as Germany, Italy and Korea, did not report a statistically significant association between the 'Western' DP and breast cancer. [22][23][24] However, the 'Drinkers' DPs, including alcoholic beverages such as wines, beers and spirits, were associated with increased risk of breast cancer, from 12% in the California Teachers' Study, through 21% in a meta-analysis of 4 studies and 40% in Uruguayan women, to 2.5 times in French women. 13,17,25,26 Alcohol is a proven risk factor for breast cancer.…”

Dietary pattern and breast cancer risk in Japanese women: the Japan Public Health Center-based Prospective Study (JPHC Study)

“…Several previous studies investigating dietary patterns in relation to breast cancer risk have shown an inverse association with the prudent/healthy dietary pattern, which usually includes high intake of vegetables, fruits, whole grains and fish (9)(10)(11)(12)(13) , and a positive association with the western/ unhealthy pattern, which is generally characterised by high intake of red meat, refined grains, potatoes and fat (14)(15)(16)(17) . Given that dietary patterns are likely to vary among populations because of geographic characteristics and cultural differences in food habits, preferences and availability (18) , these reports are of limited value for the prevention and management of breast cancer in the Japanese population.…”

Dietary patterns and breast cancer risk in a prospective Japanese study

“…Mannisto et al reported an inverse association between the Western dietary pattern and BC, and pointed out the type of fat might explain the result; butter loaded negatively on the Western pattern, but substituting low-fat margarine (which is rich in unsaturated fatty acids and is consequently healthier) loaded positively in their study [19]. A recent systematic review regarding BC risk from Western dietary patterns also showed inconsistent results [7]; that of 10 cohort studies, only one study positively associated the Western dietary pattern with BC [35], one study reported an inverse association [19], and eight found no significant association [15][16][17][18][20][21][22][23]. Moreover, another systematic review and meta-analysis found no evidence of an association between Western dietary patterns and BC risk (OR: 1.09; 95% CI: 0.98-1.22; P = 0.12) [10].…”

“…Analysis of associations between dietary patterns and BC among Japanese women could offer new insight into this field. However, almost all prospective studies of dietary patterns and BC have been undertaken in Western countries [15][16][17][18][19][20][21][22][23].…”