Breast Cancer and the Environment: A Pilot Study of Nigerian Women

Breast cancer remains the leading cause of cancer in women throughout the world, and its incidence has been increasing markedly in Africa. Women of African ancestry not only develop breast cancer at earlier ages but also have more aggressive breast cancers, with higher prevalence of TP53 mutations and triple-negative breast cancer. Although environment-induced TP53 mutagenesis has been well described in liver and lung cancers, few studies have explored its role in breast cancer. In addition, most prior studies were done in white populations and lacked generalizability to women of other ancestries. This pilot study aimed to investigate the association between environmental risk factors and somatic mutation status. A sub-aim was to evaluate the feasibility and effectiveness of a questionnaire-based method for gathering environmental exposure data. Twenty-nine patients with breast cancer and 33 patients from Ibadan, Nigeria, who had participated in the Nigerian Breast Cancer Study, were contacted to complete an environmental risks questionnaire that assessed household air pollution, diet, occupational hazards, and sleep habits. The questionnaire was translated into Yoruba and conducted with local interpreters, who obtained informed consent from all participants. Both the institutional review boards at the University of Chicago and the University of Ibadan approved the project. The results showed that cases were more likely to report living close to a major road, waste incinerator, or factory ( P = .046). There were also significant differences in occupation ( P = .000), with cases more likely to report professional occupations. They were also more likely to report occupational exposures to mineral dust, exhaust, chemicals, and endocrine disruptors; night shift work; and preference for well-done meat, although these did not reach statistical significance. This study suggests that examining exposures to environmental risk factors may be a promising avenue for future breast cancer research. The study design limited the validity of comparing exposures between cases and controls but demonstrated that a questionnaire-based method is both feasible and effective at gathering environmental exposure data. Future studies would benefit from more formal interviewer training to improve the quality of the data collection, more culturally relevant questions to assess stressful life events, and a prospective design to reduce recall bias and loss to follow-up.