Deakin University Honours project #1
Impact of dietary factors on outcomes in patients with breast cancer
Prof David Watters, AProf Douglas Stupart, Dr Eileen Moore
Department of Surgery, Deakin University; University Hospital Geelong, Barwon Health.
The purpose of this study is to determine whether patients’ diet affects the short and long term outcomes of patients who are treated for breast cancers. Around 300 patients with these cancers have had dietary assessments and measurement of bone density. This project will involve assessing their long-term oncologic and other clinical outcomes since patients were recruited over 5 years ago.
Breast cancer is the second most commonly diagnosed cancer globally, comprising 25% of cancer cases in women. Surveillance sponsored by the World Health Organisation estimates that there were 1.7 million new cases in 2012. The same report shows that the incidence was highest in North America and Oceania, with the lowest in Asia and Africa. Ferlay et al (2014) report that age-standardised rates of diagnosed breast cancer cases in 2012 were higher in economically-developed countries (74.1 cases per 100,000) than in less-developed countries (31.3 cases per 100,000). Survival after five years is ~80-90%, and higher in economically-developed nations.
The Breast Cancer Network Australia estimates that there were 15,600 women and 145 men diagnosed with breast cancer in 2015. A report of cancer incidence in aboriginal and torres strait islander people in Australia during 2013 estimated that the incidence of breast cancer was 20% lower in indigenous females when compared to non-indigenous females. Recent publicity has highlighted the role of genetic markers in the early identification of women at risk of breast cancer. However, just 5-10% of cases present with a strong family history or known genetic mutations for breast cancer.
In contrast, modifiable lifestyle factors that increase the risk for breast cancer are ubiquitous in westernised countries; such as sedentary lifestyle, alcohol consumption[6-7], premenopausal cigarette smoking, and having an unhealthy or high fat diet. Population based studies consistently report that even moderate alcohol consumption (<2 drinks per day) increases the risk for breast cancer by up to 80%[6-7] and that this risk is related to tumours that are of the ER+ subtype (estrogen-receptor positive subtype). Cigarette smoking is thought to have anti-estrogenic effects, conversely this may be protective for breast cancer. However, in a prospective cohort study in 111,140 women followed between 1976-2006 in the US Nurse’s Health Study, premenopausal cigarette smoking was associated with ~11% increased risk for breast cancer. Increased risk was associated with initiation of smoking at a younger age, and increased tobacco use.
Dietary patterns that include a high intake of fruits, vegetables, whole grains, legumes, poultry and fish may be protective for developing breast cancer[11-12] as opposed to having western dietary patterns that include refined grains, processed and red meat, and high fat intake which were associated with increased incidence of breast cancer. However, results of these studies do not show a trend for reduced breast cancer recurrence or death, so findings are difficult to interpret. Additionally, prospective studies do not support a trend between low fruit and vegetable intake and increased breast cancer risk. The same meta-analysis of prospective studies does support positive associations between low-fat diet and alcohol avoidance with reduced breast cancer risk. In addition to avoiding high-fat diets and alcohol; breast cancer risk may also be reduced through the use of omega-3 supplements to reduce estrogen synthesis in breast tissue. In a study of 35,016 post-menopausal women; current use of fish oil supplements was associated with approximately 32% reduced risk of breast cancer incidence; whereas no associations have been found with the use of other supplements, vitamins or minerals.
In summary; breast cancer risk and outcomes after breast cancer diagnosis are multifactorial and vary with region, genetics and family history, and modifiable lifestyle factors. Alcohol consumption, cigarette smoking, consuming a high fat diet and having a sedentary lifestyle have been related to poorer outcomes; whereas physical exercise, using omega-3 supplements, and consuming a low fat diet may be protective for breast cancer risk or may improve outcomes after breast cancer diagnosis. Currently there is limited information to inform best practice management for breast cancer patients in this region; therefore a study of the long term outcomes associated with dietary factors is needed.
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 Australian Institute of Health and Welfare. Cancer in Aboriginal and Torres Strait Islander peoples of Australia: an overview.
Accessed: 29 November 2015.
 Breast Cancer Network Australia. Current Statistics in Australian Breast Cancer.
Accessed: 29 November 2015
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