Lifelong vegetarianism and breast cancer risk: a large multicentre case control study in India

Toral Gathani,Parimal Jivarajani,Raghunadharao Digumarti,Rajkumar Arumugham,Hemant Malhotra,Dasappa Loknatha,Raju Chacko,Raghib Ali,Beela S Mathew,Ravi Kannan,Isobel Barnes

doi:10.1186/s12905-016-0357-8

Abstract

BackgroundThe lower incidence of breast cancer in Asian populations where the intake of animal products is lower than that of Western populations has led some to suggest that a vegetarian diet might reduce breast cancer risk.MethodsBetween 2011 and 2014 we conducted a multicentre hospital based case—control study in eight cancer centres in India. Eligible cases were women aged 30–70 years, with newly diagnosed invasive breast cancer (ICD10 C50). Controls were frequency matched to the cases by age and region of residence and chosen from the accompanying attendants of the patients with cancer or those patients in the general hospital without cancer. Information about dietary, lifestyle, reproductive and socio-demographic factors were collected using an interviewer administered structured questionnaire. Multivariate logistic regression models were used to estimate the odds ratio (OR) and 95% confidence intervals for the risk of breast cancer in relation to lifelong vegetarianism, adjusting for known risk factors for the disease.ResultsThe study included 2101 cases and 2255 controls. The mean age at recruitment was similar in cases (49.7 years (SE 9.7)) and controls (49.8 years (SE 9.1)). About a quarter of the population were lifelong vegetarians and the rates varied significantly by region. On multivariate analysis, with adjustment for known risk factors for the disease, the risk of breast cancer was not decreased in lifelong vegetarians (OR 1.09 (95% CI 0.93-1.29)).ConclusionsLifelong exposure to a vegetarian diet appears to have little, if any effect on the risk of breast cancer.

Highlights

The lower incidence of breast cancer in Asian populations where the intake of animal products is lower than that of Western populations has led some to suggest that a vegetarian diet might reduce breast cancer risk
There is little evidence to support a relationship between a vegetarian diet and subsequent breast cancer risk in cohort studies conducted in largely Western populations [6,7,8]
In this multicentre case control study in India we find no evidence of an association between exposure to a lifelong vegetarian diet and subsequent risk of breast cancer, after adjusting for known risk factors

Summary

Introduction

The lower incidence of breast cancer in Asian populations where the intake of animal products is lower than that of Western populations has led some to suggest that a vegetarian diet might reduce breast cancer risk. Breast cancer is the most commonly diagnosed cancer in women globally, with approximately 1.67 million cases in 2012 [1]. The increase in global incidence is largely attributable to rising incidence rates in less developed countries such as India, where breast cancer is the most commonly diagnosed malignancy in women with over 150 000 incident cases annually [2]. There is little evidence to support a relationship between a vegetarian diet and subsequent breast cancer risk in cohort studies conducted in largely Western populations [6,7,8]. Some small studies in India and South Asian migrants in the United Kingdom have suggested that a vegetarian diet may be associated with a reduced risk of breast cancer, the results are inconclusive [9,10,11,12]

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Results

Discussion

Conclusion