Effect of obesity on prognosis after early-stage breast cancer

The role of diet and physical activity in breast, colorectal, and prostate cancer survivorship: a review of the literature

BACKGROUND

Evidence for the role of diet and physical activity in cancer incidence is well documented, but owing to increased cancer survivorship, an understanding of these lifestyle factors after a cancer diagnosis is of crucial importance. The purpose of this review was to update the literature in a review undertaken for the National Cancer Survivorship Initiative and to include observational studies that were not included in the WCRF survivorship systematic review.

METHODS

Evidence was initially gathered from pre-defined searches of the Cochrane Library Database and PubMed from March 2006 to February 2010. After a comprehensive review regarding lifestyle and cancer, for the purpose of this article, any studies not related to diet and physical activity, prognostic outcomes, and breast, colorectal or prostate cancers were excluded. Another search of 2011 literature was conducted to update the evidence.

RESULTS

A total of 43 records were included in this review. Evidence from observational studies suggests that a low-fat, high-fibre diet might be protective against cancer recurrence and progression. However, there is a paucity of RCTs substantiating this. There is more support for physical activity, with a dose response for better outcomes. When synthesized with findings from the World Cancer Research Fund review of RCTs investigating the effect of diet and physical activity interventions on cancer survival, evidence suggests that the mechanism of benefit from diet and physical activity pertains to body weight, with excess body weight being a risk factor, which is modifiable through lifestyle.

IMPLICATIONS

Cancer survivors would like to have a more active role in their health care and to know how to look after themselves after diagnosis, including what diet and lifestyle changes they should make. The challenge is in integrating lifestyle support into standardised models of aftercare.

Lifestyle interventions for cardiovascular risk reduction in women with breast cancer

PURPOSE

The purpose of this paper is to identify risk factors for cardiovascular disease in women with breast cancer and review healthy lifestyle behaviors as essential risk reduction strategies.

FINDINGS

Women with breast cancer account for 22% of the 12 million cancer survivors. Women diagnosed with breast cancer often present with modifiable and non-modifiable cardiovascular risk factors and/or pre-existing co-morbid illness. Any one or a combination of these factors may increase the risk of cardiovascular disease. There is strong evidence that healthy eating and routine physical activity can reduce cardiovascular disease. Exercise improves cardiovascular fitness, body composition and quality of life in breast cancer survivors and observational studies suggest a survival benefit.

CLINICAL IMPLICATIONS

Lifestyle interventions including a healthy diet, regular physical activity, weight management and smoking cessation should be integrated into a survivorship care plan to reduce cardiovascular disease risk and promote better health for women with breast cancer.

Impact of comorbidity on mortality: a cohort study of 62,591 Danish women diagnosed with early breast cancer, 1990-2008

The incidence of breast cancer, as well as other chronic disease, increases with age, older breast cancer patients being more likely than younger to suffer from other diseases at time of diagnosis. Our objective was to assess the effect of comorbidity on mortality after early breast cancer. 62,591 women diagnosed with early breast cancer 1990-2008 were identified using the Danish Breast Cancer Cooperative Group Registry. Data were linked to the Danish National Patient Register and the Danish Register of Causes of Death. Main outcome measures were mortality from all causes, breast cancer, and non-breast cancer causes in relation to Charlson comorbidity index (CCI). Compared with patients without comorbidity (CCI 0), the presence of comorbidity increased the risk of dying from breast cancer as well as other causes with adjusted hazard ratios (HRs) for all-cause mortality of 1.45 (CI 95% 1.40-1.51) for CCI 1, 1.52 (95% CI 1.45-1.60) for CCI 2, and 2.21 (95% CI 2.08-2.35) for CCI 3+. Equivalent HRs for breast cancer-specific mortality were 1.30 (95% CI, 1.24-1.36) for CCI 1, 1.31 (95% CI 1.23-1.39) for CCI 2, and 1.79 (95% CI, 1.66-1.93) for CCI 3+ (all P values < 0.0001). For patients with CCI 0, 5-year overall survival increased over time from 72.5% (95% CI, 71.7-73.3%) in 1990-1994 to 81.6% (95% CI, 80.9-82.2) in 2000-2004, whereas the 5-year overall survival remained stable around 43% among the patients with CCI 3+. This population-based cohort study shows that compared with patients without comorbidity, the risk of dying from breast cancer as well as other causes increased significantly with increasing CCI score. While survival improved over time for patients without comorbidity, no improvement was seen among patients with severe comorbidity (CCI 3+).

Metabolic syndrome and triple-negative breast cancer: a new paradigm

Triple-negative breast cancers (TNBCs) are aggressive tumors with poor prognosis compared to other breast cancer subtypes. The evidence linking TNBC with the metabolic syndrome, which consists of central obesity, insulin resistance, impaired glucose tolerance, dyslipidemia, and hypertension, has emerged from clinical studies and experiments using cell lines and mouse models. Epidemiological studies have associated abdominal obesity with increased incidence of TNBC. Additionally, insulin resistance, dyslipidemia, and hypertension are associated with increased incidence of breast cancer across all subtypes. The insulin-leptin-adiponectin axis has been implicated mechanistically in breast cancer tumorigenesis. Specifically, increased leptin and decreased adiponectin levels disrupt homeostatic signaling pathways involved in cell proliferation, survival, cell-cycle regulation, and angiogenesis. Insulin, insulin-like growth factor I (IGF-I), and epidermal growth factor receptor (EGFR) may mediate interactions between these two hormones. Further research will facilitate the development of targeted therapeutics and programs to modify lifestyle factors to modulate the insulin-leptin-adiponectin axis for TNBC.

A retrospective review of the metabolic syndrome in women diagnosed with breast cancer and correlation with estrogen receptor

Women diagnosed with obesity and breast cancer have an increased risk of recurrence and death (Protani et al., Breast Cancer Res Treat 123:627-635, 1). Obesity is associated with the metabolic syndrome--a pathophysiologically distinct inflammatory process comprised of central obesity, insulin resistance, hypertension, and atherogenic dyslipidemia. The relationship of obesity as a risk factor for breast cancer is complex with a protective effect for younger women in contrast to a risk for older women (Kabat et al., Cancer Epidemiol Biomarkers Prev 18:2046-2053, 2; Ursin et al., Epidemiology 6:137-141, 3). The metabolic syndrome has been associated with the risk of cancer, and pro-inflammatory circulating factors may be associated with risk of more aggressive breast cancer (Capasso et al., Cancer Biol Ther 10:1240-1243, 4; Healy et al., Clin Oncol (R Coll Radiol) 22:281-288, 5; Laukkanen et al., Cancer Epidemiol Biomarkers Prev 13:1646-1650, 6). We conducted a retrospective review of 860 breast cancer patients to determine the relationship between estrogen receptor status and the metabolic syndrome. We collected the relevant metabolic diagnoses, medications, physical findings, and laboratory values and adapted the National Cholesterol Education Program criteria to define the metabolic syndrome retrospectively. No relationship was found between estrogen receptor status and the individual components of the metabolic syndrome. Based on findings in the medical records, 15% of the women with breast cancer had the metabolic syndrome, and 26% of the women were considered obese, 16% hyperglycemic, 54% hypertensive, and 30% dyslipidemic. The metabolic syndrome was associated with advanced age and African-American race (P < 0.001). When adjusted for age, race, and stage, the metabolic syndrome was marginally associated with estrogen receptor-positive tumors (P = 0.054). Our findings do not support the concern that the metabolic syndrome may contribute to more biologically aggressive breast cancer.

The impact of obesity on receipt of adjuvant chemotherapy for breast cancer in the National Comprehensive Cancer Network (NCCN) centers

Disparities in the receipt of adjuvant chemotherapy for early stage breast cancer is an important factor influencing mortality. We investigated whether greater body mass index (BMI) decreases receipt of adjuvant chemotherapy among women with operable breast cancer. In the NCCN breast cancer outcomes database, we identified women aged ≤ 70 with newly diagnosed stage I, II, or III breast cancer between 1997 and 2007, for whom use of adjuvant chemotherapy was classified as either standard-of-care or discretionary based on their clinical characteristics. Body mass index was assessed in categories (<18.5 kg/m(2) [underweight], 18.5 to <25 kg/m(2) [normal], 25 to <30 kg/m(2) [overweight], 30-39 kg/m(2) [obese], ≥ 40 kg/m(2) [extreme obese]). Multivariable logistic regression analysis was used to examine the association between BMI and receipt of chemotherapy in each classification group. 9,527 women were eligible for the study; 40% normal weight or less; 31% overweight; 24% obese; and 5% extremely obese. In multivariable analysis, there was no significant association between BMI and receipt of chemotherapy in either classification group. Among women for whom chemotherapy would be considered standard-of-care, older age (P < 0.001), comorbidity (P < 0.001), and non-Hispanic black ethnicity (P = 0.002) were associated with a lower likelihood of receipt of chemotherapy; however, the effect of ethnicity was not modified by obesity. Among women treated for operable breast cancer in the NCCN centers, BMI had no impact on receipt of adjuvant chemotherapy and did not modify the lower likelihood of chemotherapy among non-Hispanic black patients. Further investigation is needed into other factors that contribute to patient disparities in the receipt of chemotherapy in major academic centers.

Statin prescriptions and breast cancer recurrence risk: a Danish nationwide prospective cohort study

BACKGROUND

Accumulating evidence suggests that statins affect diseases other than cardiovascular disease, including cancer, and that these effects may depend on the lipid solubility of specific statins. Though many studies have reported an association between statin use and breast cancer incidence, the relationship between statin use and breast cancer recurrence has not been well studied.

METHODS

We conducted a nationwide, population-based prospective cohort study of all female residents in Denmark diagnosed with stage I-III invasive breast carcinoma who were reported to the Danish Breast Cancer Cooperative Group registry between 1996 and 2003 (n = 18,769). Women were followed for a median of 6.8 years after diagnosis. Prescriptions for lipophilic and hydrophilic statins were ascertained from the national electronic pharmacy database. Associations between statin prescriptions and breast cancer recurrence were estimated with generalized linear models and Cox proportional hazards regression with adjustment for age and menopausal status at diagnosis; histological grade; estrogen receptor status; receipt of adjuvant therapy; type of primary surgery received; pre-diagnosis hormone replacement therapy; and co-prescriptions of aspirin, angiotensin-converting enzyme inhibitors, nonsteroidal anti-inflammatory drugs, or anticoagulants. All statistical tests were two-sided.

RESULTS

Most prescriptions for lipophilic statins in the study population were for simvastatin. Exclusive simvastatin users experienced approximately 10 fewer breast cancer recurrences per 100 women after 10 years of follow-up (adjusted 10-year risk difference = -0.10, 95% confidence interval = -0.11 to -0.08), compared with women who were not prescribed a statin. Exclusive hydrophilic statin users had approximately the same risk of breast cancer recurrence as women not prescribed a statin over follow-up (adjusted 10-year risk difference = 0.05, 95% confidence interval = -0.01 to 0.11).

CONCLUSIONS

Simvastatin, a highly lipophilic statin, was associated with a reduced risk of breast cancer recurrence among Danish women diagnosed with stage I-III breast carcinoma, whereas no association between hydrophilic statin use and breast cancer recurrence was observed.

Effect of a low fat versus a low carbohydrate weight loss dietary intervention on biomarkers of long term survival in breast cancer patients ('CHOICE'): study protocol

Background

Weight loss in overweight or obese breast cancer patients is associated with an improved prognosis for long term survival. However, it is not clear whether the macronutrient composition of the chosen weight loss dietary plan imparts further prognostic benefit. A study protocol is presented for a dietary intervention to investigate the effects of weight loss dietary patterns that vary markedly in fat and carbohydrate contents on biomarkers of exposure to metabolic processes that may promote tumorigenesis and that are predictive of long term survival. The study will also determine how much weight must be lost for biomarkers to change in a favorable direction.

Methods/Design

Approximately 370 overweight or obese postmenopausal breast cancer survivors (body mass index: 25.0 to 34.9 kg/m²) will be accrued and assigned to one of two weight loss intervention programs or a non-intervention control group. The dietary intervention is implemented in a free living population to test the two extremes of popular weight loss dietary patterns: a high carbohydrate, low fat diet versus a low carbohydrate, high fat diet. The effects of these dietary patterns on biomarkers for glucose homeostasis, chronic inflammation, cellular oxidation, and steroid sex hormone metabolism will be measured. Participants will attend 3 screening and dietary education visits, and 7 monthly one-on-one dietary counseling and clinical data measurement visits in addition to 5 group visits in the intervention arms. Participants in the control arm will attend two clinical data measurement visits at baseline and 6 months. The primary outcome is high sensitivity C-reactive protein. Secondary outcomes include interleukin-6, tumor necrosis factor-α, insulin-like growth factor-1 (IGF), IGF binding protein-3, 8-isoprostane-F2-alpha, estrone, estradiol, progesterone, sex hormone binding globulin, adiponectin, and leptin.

Discussion

While clinical data indicate that excess weight for height is associated with poor prognosis for long term survival, little attention is paid to weight control in the clinical management of breast cancer. This study will provide information that can be used to answer important patient questions about the effects of dietary pattern and magnitude of weight loss on long term survival following breast cancer treatment.

Clinical Trial Registration

CA125243

Inflammation and increased aromatase expression occur in the breast tissue of obese women with breast cancer

Obesity is a risk factor for the development of hormone receptor-positive breast cancer in postmenopausal women and has been associated with an increased risk of recurrence and reduced survival. In humans, obesity causes subclinical inflammation in visceral and subcutaneous adipose tissue, characterized by necrotic adipocytes surrounded by macrophages forming crown-like structures (CLS). Recently, we found increased numbers of CLS, activation of the NF-κB transcription factor, and elevated aromatase levels and activity in the mammary glands of obese mice. These preclinical findings raised the possibility that the obesity → inflammation axis is important for the development and progression of breast cancer. Here, our main objective was to determine if the findings in mouse models of obesity translated to women. Breast tissue was obtained from 30 women who underwent breast surgery. CLS of the breast (CLS-B) was found in nearly 50% (14 of 30) of patient samples. The severity of breast inflammation, defined as the CLS-B index, correlated with both body mass index (P < 0.001) and adipocyte size (P = 0.01). Increased NF-κB binding activity and elevated aromatase expression and activity were found in the inflamed breast tissue of overweight and obese women. Collectively, our results suggest that the obesity → inflammation → aromatase axis is present in the breast tissue of most overweight and obese women. The presence of CLS-B may be a biomarker of increased breast cancer risk or poor prognosis.

The After Breast Cancer Pooling Project: rationale, methodology, and breast cancer survivor characteristics

The After Breast Cancer Pooling Project was established to examine the role of physical activity, adiposity, dietary factors, supplement use, and quality of life (QOL) in breast cancer prognosis. This paper presents pooled and harmonized data on post-diagnosis lifestyle factors, clinical prognostic factors, and breast cancer outcomes from four prospective cohorts of breast cancer survivors (three US-based and one from Shanghai, China) for 18,314 invasive breast cancer cases diagnosed between 1976 and 2006. Most participants were diagnosed with stage I-II breast cancer (84.7%). About 60% of breast tumors were estrogen receptor (ER)+/progesterone receptor (PR)+; 21% were ER-/PR-. Among 8,118 participants with information on HER-2 tumor status, 74.8% were HER-2- and 18.5% were HER-2+. At 1-2 years post-diagnosis (on average), 17.9% of participants were obese (BMI ≥ 30 kg/m2), 32.6% were overweight (BMI 25-29 kg/m2), and 59.9% met the 2008 Physical Activity Guidelines for Americans (≥ 2.5 h per week of moderate activity). During follow-up (mean = 8.4 years), 3,736 deaths (2,614 from breast cancer) and 3,564 recurrences have been documented. After accounting for differences in year of diagnosis and timing of post-diagnosis enrollment, five-year overall survival estimates were similar across cohorts. This pooling project of 18,000 breast cancer survivors enables the evaluation of associations of post-diagnosis lifestyle factors, QOL, and breast cancer outcomes with an adequate sample size for investigation of heterogeneity by hormone receptor status and other clinical predictors. The project sets the stage for international collaborations for the investigation of modifiable predictors for breast cancer outcomes.

Associations of physical activity with quality of life and functional ability in breast cancer patients during active adjuvant treatment: the Pathways Study

Physical activity can improve quality of life (QOL) in breast cancer survivors but little is known about associations of physical activity and QOL during active cancer therapy. We examine associations between activity levels and QOL in a large cohort of breast cancer patients. Women with invasive, non-metastatic breast cancer (n=2,279) were enrolled between 2006 and 2009 from a managed care organization; assessment were done during active therapy. A physical activity frequency questionnaire was used to calculate the average weekly metabolic equivalent task (MET) hours spent in moderate and vigorous activity during active treatment. QOL was measured by the Functional Assessment of Cancer Therapy-Breast Cancer. Linear regression models tested cross-sectional associations of QOL and functional well-being with physical activity and covariates [socio-demographics, comorbidity, body mass index (BMI), clinical variables, social support, and assessment timing]. Physical activity had a significant positive unadjusted association with all QOL sub-scales (except emotional well-being) (all P values < 0.01). Overall QOL was 4.6 points higher for women in the highest quartile of moderate and vigorous activity versus women in the lowest quartile (P<0.001). In regression models, higher activity was associated with better overall QOL and functional well-being, controlling for covariates (P<0.05). Increasing BMI was also independently but inversely associated with overall QOL (P<0.001) but did not explain the relationship of activity and QOL. White women reported the higher levels of activity than minority women and activity was associated with QOL for Whites but not for minority women. Greater physical activity is associated with small but clinically meaningful increases in QOL during active breast cancer care therapy for Whites but this effect is not seen for minority women. If confirmed in longitudinal analyses, these differences may have implications for disparities research.