Abstract and Introduction
Advances in diagnostic screening and adjuvant therapy have dramatically increased the number of breast cancer survivors in the USA, who may face changes in physical and mental health, social support, quality of life and economics. Women living with breast cancer are increasingly interested in lifestyle modification to decrease the risk of recurrence and mortality while increasing physical and emotional wellbeing. Although organizations such as the American Cancer Society support a healthy diet, frequent physical activity and stress reduction for decreasing breast cancer risk, studies examining the effects of lifestyle on clinical outcomes including survival and prognosis have been inconclusive. With the number of breast cancer survivors predicted to increase to 3.4 million by 2015, it is important to develop effective treatment paradigms that overcome barriers to behavioral modification to improve clinical outcomes and survivorship in breast cancer patients.
Breast cancer is the most frequently occurring cancer in women and is second only to lung cancer in lethality. Over the last 50 years, lifetime risk of breast cancer has increased such that today one in eight women are expected to develop breast cancer. Projections indicated that more than 230,000 new breast cancers would be diagnosed and approximately 40,000 women would die from breast cancer in the USA in 2011. Mortality rates increased from 1970 to 1990, but in recent years death rates have decreased by 28%. This notable decline in mortality, likely attributable to improvements in early detection and adjuvant therapy, has produced more than 2.5 million breast cancer survivors in the USA today but this number is expected to increase to 3.4 million by 2015.
The term 'breast cancer survivor' applies to individuals from the time of diagnosis through the remainder of their life, and includes patients recently diagnosed with breast cancer, undergoing active treatment or post-treatment follow-up, as well as those living with terminal disease. These survivors face numerous issues, including detrimental changes in physical activity, social support, psychological health and personal finance, which can impact long-term survival and quality of life (QoL). Survivors may suffer from anxiety, depression, fear of recurrence, impaired body image and increased risk of comorbid conditions.[6–8] Although factors that influence survival are often not the same as those affecting QoL, and interventions designed to address one outcome may be ineffective in modifying the other, it is imperative to understand how lifestyle modification can improve relapse-free survival and/or QoL in breast cancer survivors.
Standard treatment for breast cancer in the USA includes surgery with or without radiation, hormone therapy and chemotherapy. Although state-of-the-art medical care has increased the number of survivors, these treatments often result in significant negative sequelae and many women suffer recurrence or breast cancer mortality. Studies of behavioral modification in breast cancer survivors are providing new information about how lifestyle factors such as diet, physical activity and stress affect survivorship, as well as knowledge to develop new and more effective intervention programs for survivors. Our main thesis in this review is that lifestyle changes in breast cancer survivors may complement traditional medical treatments and improve clinical outcomes such as recurrence and survival. Beginning with an overview of the relationship between obesity and breast cancer, we then examine data from large prospective cohort studies and randomized controlled trials investigating the role of diet on breast cancer prognosis. Although information is currently limited on other dietary factors that may have lesser impact on long-term survival, we consider the possible effects of alcohol, functional foods and nutraceuticals. We then discuss how physical activity may improve prognosis and highlight recent sentinel studies that have fundamentally changed the management of lymphedema. As complementary and alternative medicine (CAM) approaches, which are currently outside the standard of care, are gaining in popularity among breast cancer survivors, we examine whether therapeutic approaches to stress reduction actually improve patient survival or affect QoL. We conclude with discussions of lifestyle modification in patients with metastasis, who have different health concerns than women with early-stage disease, limitations to current study designs and barriers to widespread implementation of lifestyle modification strategies.
Expert Rev Pharmacoeconomics Outcomes Res. 2012;12(4):451-464. © 2012 Expert Reviews Ltd.