Missed Opportunities for Chronic Disease Prevention after Breast Cancer

“Many cancer survivors are motivated to improve their lifestyle, so we need to better capitalize on this potential to improve overall health. There is no reason that a diagnosis of breast cancer should not lead a woman to a better state of health than she had before breast cancer.”

For most women, having a diagnosis of breast cancer is a life-transforming experience. Hearing the words ‘you have breast cancer’ is often equivalent to hearing ‘you might die’. For most breast cancer survivors, the physical and psychological consequences of that diagnosis lead them to see the world differently thereafter [1]. The fact that breast cancer becomes one's leading health concern is understandable, of course, as treatment decisions, the management of side effects and the risk of recurrence justify considerable attention. But is there risk that the breast cancer experience might eclipse other legitimate concerns about chronic disease prevention? We think so. Breast cancer survivors are at increased risk for many other preventable chronic diseases, including heart disease, stroke and diabetes mellitus, but seeing the world largely through the breast cancer experience can sometimes lead both breast cancer survivors and their providers to underachieve prevention for other conditions.

“Whether patients with compromised health conditions respond as well to cancer treatment is not certain and needs further attention.”

Breast cancer is primarily a disease that affects women after the age of 50 years. In fact, about half of all breast cancers are diagnosed among women older than 65 years [101]. The middle to older adult stages of life bring risk factors for not only breast cancer, but also for other chronic diseases. Chief among these risk factors are obesity and physical inactivity, which increase risk for not only breast cancer, but also heart disease, stroke and diabetes mellitus [2,3]. Women over the age of 50 years diagnosed with breast cancer are less physically active and more overweight than other women of the same age, and hence are at increased risk for heart disease, stroke and diabetes at the point of their breast cancer diagnosis [2,3]. Following cancer diagnosis comes various breast cancer treatments, all of which tend to worsen these same risk factors. There is a common misperception that treatments for breast cancer cause weight loss. In fact, breast cancer survivors tend to gain weight, particularly fatty tissue weight, with treatments [4,5]. This is due in part to metabolic effects of anti-estrogens and chemotherapies, as well as to the reduced physical activity that comes with the experiences of surgery, radiation therapy and the many dimensions of psychosocial turmoil that surround breast cancer treatment [6].

Our direct knowledge of the long-term consequences of increased adiposity and reduced physical activity for survival and outcomes after breast cancer comes from observational cohort studies of breast cancer survivors. Both physical inactivity and obesity are major risk factors for breast cancer recurrence. Women who are overweight have a 78% higher risk for breast cancer recurrence within 5 years than women who are not overweight, and women who are physically inactive have twice the risk for recurrence compared with women who are even moderately physically active (brisk walking 30 min/day) [7,8]. The mechanisms for this increased risk seem to be multifactorial, including adverse effects of obesity and physical inactivity on estrogen metabolism, cytokine levels, and levels of insulin and IGFs [9]. These same factors are also associated with increased risk for cardiovascular diseases [3].

Both the decisions about treatment of breast cancer and the tolerance to treatment can be influenced by other comorbid conditions. Knowledge of the effect of comorbid conditions on survival and outcomes after breast cancer is limited by the fact that randomized controlled trials of breast cancer treatment tend to systematically disqualify older women and women with other chronic diseases [10]. Whether patients with compromised health conditions respond as well to cancer treatment is not certain and needs further attention. In the meantime, we are able to assess the impact of other chronic diseases on survival after breast cancer by examining large administrative datasets, such as Medicare [11]. We analyzed a large cohort of US women diagnosed with breast cancer after the age of 65 years in the Medicare system and found that comorbidities at the time of cancer diagnosis have a substantial influence on survival [12,13]. Among almost 65,000 women diagnosed with breast cancer between 1992 and 2000 and followed through 2005, we found that more than twice as many deaths occured due to other chronic diseases than due to breast cancer. Approximately half of the women died during the study period, but only 29% of those deaths were due directly to breast cancer. The leading cause of death among Medicare breast cancer survivors was cardiovascular disease, which caused 31% of all deaths. We also found that patients with a comorbid condition and stage I breast cancer had overall survival that was similar to or worse than patients with stage II tumors but no comorbid conditions; patients with a comorbid condition and stage II breast cancer had overall survival that was similar to or worse than patients with stage III and IV tumors but no comorbid conditions.

“Cardiac rehabilitation is now the accepted norm after a myocardial infarction, but cancer rehabilitation is not yet a norm after breast cancer, despite the fact that many small-scale randomized controlled trials have shown that increased physical activity improves many facets of quality of life for breast cancer survivors.”

So if other chronic diseases are surprisingly common after breast cancer and even more common than breast cancer itself as a cause of death, and if having heart disease, stroke, diabetes or any of several other chronic conditions shifts prognosis by at least one breast cancer stage, how should chronic conditions be considered and acted upon after a diagnosis of breast cancer? Many chronic conditions can now be effectively managed with careful attention to drug doses and levels of intermediating factors, such as blood pressure and lipoprotein concentrations [14]. Modifiable behavioral risk factors such as obesity and physical inactivity, which increase risk for common chronic diseases such as heart disease, stroke and diabetes, should be priorities for everyone, of course, but especially for breast cancer survivors. Nonetheless, the experience of having had breast cancer can distract needed attention away from chronic disease risk factor control. Surgeons, medical oncologists and radiation therapists necessarily become the primary caregivers for breast cancer survivors during the several months of the first course of treatment, but those relationships can persist into longer term relationships that may last many years. This prolonged focus on breast cancer by both patients and providers can lead to insufficient attention to the many other clinical and behavioral opportunities to reduce the risk for other chronic diseases. This problem was addressed by The Institute of Medicine (IOM) in their 2005 report From Cancer Patient to Cancer Survivor: Lost in Transition. The report described the many issues of coordinating healthcare following a cancer diagnosis [15]. Oftentimes, primary care providers are not sufficiently aware of cancer treatment and follow-up issues, so cancer survivors can develop an over-reliance on specialists for their primary care. The IOM recommended that each cancer patient receive a ‘survivorship care plan’ in order to integrate cancer care, psychosocial support, follow-up care and maintenance of a healthy lifestyle. Still, 6 years after publication of this report, there has been little improvement in integrating primary care and long-term health improvement for cancer survivors. Cardiac rehabilitation is now the accepted norm after a myocardial infarction, but cancer rehabilitation is not yet a norm after breast cancer, despite the fact that many small-scale randomized controlled trials have shown that increased physical activity improves many facets of quality of life for breast cancer survivors [16]. Whether weight loss might both improve quality of life and reduce breast cancer recurrence among overweight women diagnosed with breast cancer is now being tested in Exercise and Nutrition to Enhance Recovery and Good Health for You (ENERGY), a randomized controlled trial of 800 overweight breast cancer survivors in four US centers [102].

There are many opportunities to reduce risk for several common chronic diseases after treatment for breast cancer. Breast cancer survivors and the healthcare providers who care for them need to not only focus on concerns about breast cancer treatment follow-up, but also need to be aware of the higher risk for other preventable conditions faced by breast cancer survivors. Careful control of hypertension, elevated serum lipids, tobacco cessation, weight control and physical activity should all become more important, not less important, after breast cancer. Although the prevention of other chronic diseases may not be an immediate priority at the time of cancer diagnosis, the diagnosis of breast cancer should be seen as a wake-up call for the prevention of other chronic diseases. Many cancer survivors are motivated to improve their lifestyle, so we need to better capitalize on this potential to improve overall health. There is no reason that a diagnosis of breast cancer should not lead a woman to a better state of health than she had before breast cancer. Looking at the world ‘through pink-colored glasses’ should not be hazardous to a woman's health.