Metformin in early breast cancer: a prospective window of opportunity neoadjuvant study

Metformin may exert anti-cancer effects through indirect (insulin-mediated) or direct (insulin-independent) mechanisms. We report results of a neoadjuvant "window of opportunity" study of metformin in women with operable breast cancer. Newly diagnosed, untreated, non-diabetic breast cancer patients received metformin 500 mg tid after diagnostic core biopsy until definitive surgery. Clinical (weight, symptoms, and quality of life) and blood [fasting serum insulin, glucose, homeostasis model assessment (HOMA), C-reactive protein (CRP), and leptin] attributes were compared pre- and post-metformin as were terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL) and Ki67 scores (our primary endpoint) in tumor tissue. Thirty-nine patients completed the study. Mean age was 51 years, and metformin was administered for a median of 18 days (range 13-40) up to the evening prior to surgery. 51 % had T1 cancers, 38 % had positive nodes, 85 % had ER and/or PgR positive tumors, and 13 % had HER2 overexpressing or amplified tumors. Mild, self-limiting nausea, diarrhea, anorexia, and abdominal bloating were present in 50, 50, 41, and 32 % of patients, respectively, but no significant decreases were seen on the EORTC30-QLQ function scales. Body mass index (BMI) (-0.5 kg/m(2), p < 0.0001), weight (-1.2 kg, p < 0.0001), and HOMA (-0.21, p = 0.047) decreased significantly while non-significant decreases were seen in insulin (-4.7 pmol/L, p = 0.07), leptin (-1.3 ng/mL, p = 0.15) and CRP (-0.2 mg/L, p = 0.35). Ki67 staining in invasive tumor tissue decreased (from 36.5 to 33.5 %, p = 0.016) and TUNEL staining increased (from 0.56 to 1.05, p = 0.004). Short-term preoperative metformin was well tolerated and resulted in clinical and cellular changes consistent with beneficial anti-cancer effects; evaluation of the clinical relevance of these findings in adequately powered clinical trials using clinical endpoints such as survival is needed.

Obesity and insulin resistance in breast cancer--chemoprevention strategies with a focus on metformin

Obesity and insulin resistance have been associated with breast cancer risk, and breast cancer outcomes. Recent research has focused on insulin as a potential biologic mediator of these effects given frequent expression of insulin/IGF-1 receptors on breast cancer cells which, when activated, can stimulate signaling through PI3K and Ras-Raf signaling pathways to enhance proliferation. Metformin, a commonly used diabetes drug, lowers insulin in non-breast diabetic cancer patients, likely by reducing hepatic gluconeogenesis; it also appears to have potential insulin independent direct effects on tumor cells which are mediated by activation of AMPK with downstream inhibition of mTOR. There is growing epidemiologic, clinical and preclinical (in vitro and in vivo) evidence in keeping with anticancer effects of metformin in breast and other cancers. This has led to the hypothesis that metformin may be effective in breast cancer prevention and treatment. Clinical studies in the neoadjuvant and adjuvant settings are ongoing; additional Phase 2 trials in the metastatic setting and proof of principle studies in the prevention setting are planned.

The role of obesity in cancer survival and recurrence

Obesity and components of energy imbalance, that is, excessive energy intake and suboptimal levels of physical activity, are established risk factors for cancer incidence. Accumulating evidence suggests that these factors also may be important after the diagnosis of cancer and influence the course of disease, as well as overall health, well-being, and survival. Lifestyle and medical interventions that effectively modify these factors could potentially be harnessed as a means of cancer control. However, for such interventions to be maximally effective and sustainable, broad sweeping scientific discoveries ranging from molecular and cellular advances, to developments in delivering interventions on both individual and societal levels are needed. This review summarizes key discussion topics that were addressed in a recent Institute of Medicine Workshop entitled, "The Role of Obesity in Cancer Survival and Recurrence"; discussions included (i) mechanisms associated with obesity and energy balance that influence cancer progression; (ii) complexities of studying and interpreting energy balance in relation to cancer recurrence and survival; (iii) associations between obesity and cancer risk, recurrence, and mortality; (iv) interventions that promote weight loss, increased physical activity, and negative energy balance as a means of cancer control; and (v) future directions.

Feasibility of a randomized controlled trial of vitamin D vs. placebo in women with recently diagnosed breast cancer

Low serum vitamin D levels have been associated with poor outcomes in women diagnosed with early breast cancer. However, no randomized controlled trials (RCTs) have been performed to determine whether vitamin D supplementation might be an effective intervention in this population. We prospectively evaluated vitamin D adequacy and supplementation rates in a contemporary cross-sectional sample of breast cancer patients from 2 large urban centers and examined the feasibility of an RCT of vitamin D supplementation. Women with recently diagnosed early breast cancer were prospectively identified and recruited in Toronto and Los Angeles between March 2009 and January 2010. Anthropometric measurements, dietary, lifestyle, and medication histories were obtained by means of structured questionnaires and interviews. Tumor and treatment characteristics were abstracted from clinical records and blood samples were collected for analysis of 25-OH vitamin D. 173 eligible patients (median age 57) were enrolled. Clinical and treatment characteristics were similar between centres. 84.4 % of women reported use of vitamin D-containing supplements with median daily doses of 1,400 IU. Median 25-OH vitamin D levels were 85.5 and 98.5 nmol/L (P = 0.1), and levels of deficiency (<50 nmol/L), insufficiency (50-72 nmol/L), and adequacy (>72 nmol/L) were 3.8, 23.8, 72.5 % (Toronto) and 4.3, 20.7, 75 % (Los Angeles). 25-OH vitamin D levels were strongly correlated with vitamin D supplement use (r = 0.41, P < 0.0001). 68 % of women expressed willingness to participate in a vitamin D supplementation RCT; however, only 12.7 % of the study population met the pre-specified feasibility criteria (25-OH vitamin D <72 nmol/L, willing to participate, and taking ≤1,000 IU vitamin D supplement/day). Both vitamin D levels and supplementation rates are higher than in previous reports. While the majority of women would be willing to participate in an RCT of vitamin D supplementation, low levels of deficiency/insufficiency and high rates of supplement use would limit the feasibility of such a study.

Metformin in cancer: translational challenges

The anti-diabetic drug metformin is rapidly emerging as a potential anti-cancer agent. Metformin, effective in treating type 2 diabetes and the insulin resistance syndromes, improves insulin resistance by reducing hepatic gluconeogenesis and by enhancing glucose uptake by skeletal muscle. Epidemiological studies have consistently associated metformin use with decreased cancer incidence and cancer-related mortality. Furthermore, numerous preclinical and clinical studies have demonstrated anti-cancer effects of metformin, leading to an explosion of interest in evaluating this agent in human cancer. The effects of metformin on circulating insulin levels indicate a potential efficacy towards cancers associated with hyperinsulinaemia; however, metformin may also directly inhibit tumour growth. In this review, we describe the mechanism of action of metformin and summarise the epidemiological, clinical and preclinical evidence supporting a role for metformin in the treatment of cancer. In addition, the challenges associated with translating preclinical results into therapeutic benefit in the clinical setting will be discussed.

PD04-09: Self-Reported Cognitive Attributes and Fatigue Improve over Long-Term Follow-Up in Breast Cancer Survivors; Some Cognitive Attributes Are Worse in Breast Cancer Survivors Than in Non-Cancer Controls

Background: Cognitive deficits and fatigue have been reported in breast cancer (BC) patients undergoing a variety of treatments, including chemotherapy; in some studies these concerns persist after completion of treatment. We examined these factors over time (median 11 yrs) in a longitudinal study of BC patients and compared the status of long-term BC survivors to non-BC controls.

Methods: 535 T1-3, N0-1, M0 BC patients were enrolled 1989–96; 260 women survived without metastases to participate in long-term follow-up (LTFU) measurements in 2006–8. 161 controls without BC were enrolled 2007–8. Questionnaires examined a range of QOL attributes; here we focus on items related to cognition and fatigue including: EORTC QLQ C30 (cognitive functioning, fatigue), Profile of Mood States (POMS — confusion/bewilderment, fatigue/inertia, vigor/activity), Fatigue Symptom Inventory (FSI — average fatigue past week, total disruption index), Everyday Problems (EDP — forgetfulness, difficulty concentrating, easily distracted). 166 of the BC patients had also completed EORTC and POMS at diagnosis and 1 year, and change in items on these questionnaires was calculated. Age and income adjusted differences between BC (LTFU) and controls were analyzed. Clinical significance was defined as ≥5% of the scale range or an effect size of ≥0.2 and statistical significance as P≤ 0.05.

Results: BC cases were older than controls (62.3 vs 59.1 yr), had lower education (24.6 vs 10.2% high school only) and family income (38.2 vs 19.8% &lt; $60,000 annually) (all P&lt;0.01). Cognitive attributes: BC patients showed clinically and statistically significant improvements between diagnosis and LTFU on POMS confusion/bewilderment but not EORTC cognitive functioning. Comparing BC (LTFU) to controls, in multivariate analyses adjusted for age and income, EORTC cognitive functioning (81.5 vs 87.4) and EDP forgetfulness (0.9 vs 0.6) were clinically and statistically significantly worse in BC patients than controls. In contrast, POMS confusion/bewilderment, EDP difficulty concentrating and EDP easily distracted scores were similar in BC patients at LTFU and controls. Fatigue: BC patients showed clinically and statistically significant improvements between diagnosis and LTFU on EORTC fatigue, POMS fatigue/inertia and POMS vigor/activity. After adjustment for age and income there were no clinically and statistically significant differences between BC (LTFU) and controls on any fatigue items.

Conclusions: Fatigue items, as well as some cognitive items, improved over time in BC patients and scores were comparable to scores in non-BC controls at LTFU. However, scores on some cognitive items were worse in LTFU BC patients than in non-BC controls raising concerns that BC diagnosis and treatment may be associated with long-term adverse effects on some aspects of self-reported cognitive attributes.

(Funded by The Breast Cancer Research Foundation)

Citation Information: Cancer Res 2011;71(24 Suppl):Abstract nr PD04-09.

P4-12-05: Impact of the Lifestyle Intervention Study in Adjuvant Treatment of Early Breast Cancer (LISA) Weight Loss Intervention upon Physical Activity

Observational evidence shows a relationship between obesity and poor prognosis in breast cancer (BC). Physical activity (PA) is an important component of weight loss and maintenance, but most large-scale interventions in BC patients have produced only modest improvements in activity. We sought to evaluate changes in PA in women participating in LISA, a randomized trial coordinated by the Ontario Clinical Oncology Group which was designed to examine the impact of a telephone-based weight loss intervention (WLI) upon disease free survival in BC patients.

Methods: Participants were randomized 1:1 to the WLI or educational control (EC) group. Eligibility included diagnosis of Stage I-III BC, BMI ≥24 kg/m2, and treatment with letrozole. The WLI, based on the Diabetes Prevention Program, focused on weight reduction through calorie restriction and increased physical activity. Delivery involved 19 calls, mailings and a participant manual. The PA goal was 150 minutes/week. PA was measured using the International Physical Activity Questionnaire (Short Form) at baseline, 6, 12, and 18 months. Changes in time (minutes/week) spent sitting and engaging in moderate, vigorous, and walking activities were compared between groups.

Results 338 women were randomized to WLI (n=171) or EC (n=167) from 20 centers in Canada and the USA. The study was discontinued due to loss of funding. The WLI arm lost significantly more weight than EC arm, with mean weight loss of 6.1% of body weight vs. 0.6% at 12 months (p&lt;0.001). Activity data are presented in Table 1. At baseline, participants were inactive; median vigorous activity was zero minutes/week and median time spent sitting was more than 35 hours/week. WLI participants reported significantly higher participation in vigorous, moderate and walking activities, and lower levels of sedentary behavior, compared to controls at 6 and 12 months. Higher levels of PA were significantly associated with increased weight loss at all time periods. Factors associated with increases in activity included higher baseline BMI (p=0.014), lower baseline activity (p&lt;0.001) and assignment to the WLI arm (p=0.02). Women assigned to WLI increased their PA during the intervention period (p=0.017) even after adjusting for other significant baseline factors.

Conclusion Participants in the LISA WLI reported significantly higher levels of PA compared with controls. Activity increased most in women who were heavier and less active at baseline. Further study of this WLI as a potential means to improve BC outcomes is warranted.

P4-10-02: A Meta-Analysis of the Association of Blood Levels of Vitamin-D and the Risk of Breast Cancer

Background: A considerable body of literature has examined the association of vitamin-D with breast cancer risk and the potential role in its prevention. Geographic studies show higher incidence of breast cancer in patients residing at high latitudes. Other data linking vitamin-D deficiency to breast cancer risk are inconsistent.

Materials and Methods: A literature based meta-analysis was conducted. Odds ratios (OR) for breast cancer based on blood levels of 25-hydroxy or 1,25-hydroxy vitamin-D were computed and pooled. Analysis was conducted separately for studies where blood levels were taken before (group A) or after (group B) breast cancer diagnosis.

Results: Thirteen studies were identified. Nine studies were included in group A and 4 studies included in group B. For group A, there was no significant association between lower vitamin-D levels and breast cancer risk (pooled OR = 1.09, 95% confidence intervals 0.99−1.20, p=0.08). For group B, there was a highly significant association between lower vitamin-D levels and breast cancer (pooled OR = 2.81, 95% confidence intervals 1.70−4.65, p&lt;0.001). The test for interaction between groups was highly significant (p&lt;0.001). When all studies were pooled, the OR was 1.38 (95% confidence intervals 1.13−1.70, p=0.002).

Conclusion: When measured before breast cancer diagnosis, blood levels of vitamin-D are not associated with breast cancer risk. Breast tumors have been shown to differentially express vitamin-D hydroxylase. Therefore, any association of vitamin-D and breast cancer in studies measuring blood levels after breast cancer diagnosis may be confounded by reverse causation bias.

Citation Information: Cancer Res 2011;71(24 Suppl):Abstract nr P4-10-02.

Insulin- and obesity-related variables in early-stage breast cancer: correlations and time course of prognostic associations

PURPOSE

To investigate patterns of prognostic associations over time of insulin- and obesity-related variables measured at diagnosis of early breast cancer (BC), focusing on whether the prognostic associations with distant recurrence and death changed over time.

PATIENTS AND METHODS

Five hundred thirty-five nondiabetic women with T1-3, N0-1, M0 invasive BC diagnosed from 1989 to 1996 were included in the study. Insulin-related variables included fasting insulin, Homeostasis Model Assessment, C-peptide, and glucose. Obesity-related variables included weight, body mass index (BMI), waist and hip circumference, and leptin. Correlations were examined using the Pearson correlation coefficient and prognostic associations using the Cox model.

RESULTS

There was evidence that associations of baseline insulin-related variables with distant recurrence and death were not constant over time; univariable adverse prognostic associations were significant only during the first 5 years (eg, insulin quartile 4 v 1: hazard ratio [HR], 2.32; 95% CI, 1.39 to 3.86; P < .001 for distant disease-free survival [DDFS]; and HR, 2.85; 95% CI, 1.48 to 5.50; P = .002 for overall survival [OS], with little attenuation of this pattern in multivariable analyses). In contrast, obesity-related variables (BMI, weight, leptin) exerted significant adverse univariable associations that were constant over time (eg, BMI quartile 4 v 2: HR, 1.40; 95% CI, 1.07 to 1.82 for DDFS; P = .014; and HR, 1.50; 95% CI, 1.16 to 1.93; P < .001 for OS); prognostic associations of leptin remained significant in multivariable analyses.

CONCLUSION

Baseline insulin- and obesity-related variables exert different patterns of prognostic associations over time in early BC.

Breast cancer prognosis in BRCA1 and BRCA2 mutation carriers: an International Prospective Breast Cancer Family Registry population-based cohort study

PURPOSE

To compare breast cancer prognosis in BRCA1 and BRCA2 mutation carriers with that in patients with sporadic disease.

PATIENTS AND METHODS

An international population-based cohort study was conducted in Canada, the United States, and Australia of 3,220 women with incident breast cancer diagnosed between 1995 and 2000 and observed prospectively. Ninety-three had BRCA1 mutations; 71, BRCA2 mutations; one, both mutations; 1,550, sporadic breast cancer; and 1,505, familial breast cancer (without known BRCA1 or BRCA2 mutation). Distant recurrence and death were analyzed.

RESULTS

Mean age at diagnosis was 45.3 years; mean follow-up was 7.9 years. Risks of distant recurrence and death did not differ significantly between BRCA1 mutation carriers and those with sporadic disease in univariable and multivariable analyses. Risk of distant recurrence was higher for BRCA2 mutation carriers compared with those with sporadic disease in univariable analysis (hazard ratio [HR], 1.63; 95% CI, 1.02 to 2.60; P = .04). Risk of death was also higher in BRCA2 carriers in univariable analysis (HR, 1.81; 95% CI, 1.15 to 2.86; P = .01). After adjustment for age, tumor stage and grade, nodal status, hormone receptors, and year of diagnosis, no differences were observed for distant recurrence (HR, 1.00; 95% CI, 0.62 to 1.61; P = 1.00) or death (HR, 1.12; 95% CI, 0.70 to 1.79; P = .64).

CONCLUSION

Outcomes of BRCA1 mutation carriers were similar to those of patients with sporadic breast cancer. Worse outcomes in BRCA2 mutation carriers in univariable analysis seem to reflect the presence of more adverse tumor characteristics in these carriers. Similar outcomes were identified in BRCA2 carriers and those with sporadic disease in multivariable analyses.

Abstract PL02-02: Energy balance and cancer prevention: Lessons learned from clinical research

Energy balance is associated with risk of development of many common cancers, and with clinical outcomes after cancer diagnosis in several solid tumors. Higher BMI leads to an increased risk of most solid tumors and hematologic malignancies. Exceptions in both sexes include lung and esophageal cancer; in women they also include premenopausal breast cancer (Renehan et al Lancet 2008). Physical inactivity has been convincingly or probably associated with increased risk of cancer of the breast, colon and endometrial cancer and possibly associated with an increased risk of lung, prostate and ovarian cancers; it has been estimated risk of these cancers might be reduced by 20–30% in active individuals (Friedenreich C et al Eur J Cancer 2010). Furthermore, observational data suggest that cancer risk may be reduced in obese individuals who undergo bariatric surgery (Renehan Lancet Oncology 2009) and that risk of obesity-related cancers (breast, colon, endometrial, any obesity associated cancer) is reduced in individuals reported an intentional weight loss of 20 pounds or more. Similar associations have been reported in patients diagnosed with several common types of cancer. For example, higher BMI has been convincingly associated with poor breast cancer outcomes; meta-analyses suggest relative risk of recurrence or death is increased by 25–40% in obese women. Evidence is less convincing for colorectal cancer; obesity may be associated with prostate cancer having more aggressive characteristics. Higher levels of physical activity pre and/or post diagnosis have been associated with improved outcomes in breast and colorectal cancer. One randomized trial involving 2437 early stage breast cancer patients reported improved relapse free survival (HR 0.96, 95%CI 0.60–0.98) in those randomized to a reduced fat diet (associated with modest weight loss) versus controls. A second RCT in breast cancer survivors failed to identify a prognostic effect of a more complex dietary intervention that lowered fat intake but was not associated with weight loss. Intervention studies have convincingly demonstrated that modification of energy balance (physical activity, dietary change, weight loss) in cancer patients is feasible, particularly in those with breast cancer, but confirmation of beneficial effects on cancer outcomes is lacking. Potential physiologic mediators of prognostic effects of energy balance include members of the insulin/insulin-like growth factor pathway, inflammation, adipocytokines and sex hormones; it is likely the relative importance of these factors varies across tumor types. Large scale intervention studies targeting energy balance, its components (e.g. physical activity) and/or key physiologic mediators are needed to provide high level evidence regarding benefits of modifying energy balance, or its physiologic mediators. One study targeting insulin (MA32) is underway in breast cancer survivors; others have been proposed.

Citation Information: Cancer Prev Res 2011;4(10 Suppl):PL02-02.

Understanding the benefit of metformin use in cancer treatment

Biguanides have been developed for the treatment of hyperglycemia and type 2 diabetes. Recently, metformin, the most widely prescribed biguanide, has emerged as a potential anticancer agent. Epidemiological, preclinical and clinical evidence supports the use of metformin as a cancer therapeutic. The ability of metformin to lower circulating insulin may be particularly important for the treatment of cancers known to be associated with hyperinsulinemia, such as those of the breast and colon. Moreover, metformin may exhibit direct inhibitory effects on cancer cells by inhibiting mammalian target of rapamycin (mTOR) signaling and protein synthesis. The evidence supporting a role for metformin in cancer therapy and its potential molecular mechanisms of action are discussed.

Quality-of-life measurement in randomized clinical trials in breast cancer: an updated systematic review (2001-2009)

BACKGROUND

Quality-of-life (QOL) measurement is often incorporated into randomized clinical trials in breast cancer. The objectives of this systematic review were to assess the incremental effect of QOL measurement in addition to traditional endpoints (such as disease-free survival or toxic effects) on clinical decision making and to describe the extent of QOL reporting in randomized clinical trials of breast cancer.

METHODS

We conducted a search of MEDLINE for English-language articles published between May-June 2001 and October 2009 that reported: 1) a randomized clinical trial of breast cancer treatment (excluding prevention trials), including surgery, chemotherapy, hormone therapy, symptom control, follow-up, and psychosocial intervention; 2) the use of a patient self-report measure that examined general QOL, cancer-specific or breast cancer-specific QOL or psychosocial variables; and 3) documentation of QOL outcomes. All selected trials were evaluated by two reviewers, and data were extracted using a standardized form for each variable. Data are presented in descriptive table formats.

RESULTS

A total of 190 randomized clinical trials were included in this review. The two most commonly used questionnaires were the European Organization for Research and Treatment of Cancer QOL Questionnaire and the Functional Assessment of Cancer Therapy/Functional Assessment of Chronic Illness Therapy. More than 80% of the included trials reported the name(s) of the instrument(s), trial and QOL sample sizes, the timing of QOL assessment, and the statistical method. Statistical power for QOL was reported in 19.4% of the biomedical intervention trials and in 29.9% of the nonbiomedical intervention trials. The percentage of trials in which QOL findings influenced clinical decision making increased from 15.2% in the previous review to 30.1% in this updated review for trials of biomedical interventions but decreased from 95.0% to 63.2% for trials of nonbiomedical interventions. Discordance between reviewers ranged from 1.1% for description of the statistical method (yes vs no) to 19.9% for the sample size for QOL.

CONCLUSION

Reporting of QOL methodology could be improved.

Multicenter, Randomized, Cross-Over Clinical Trial of Venlafaxine Versus Gabapentin for the Management of Hot Flashes in Breast Cancer Survivors

Purpose

Nonhormonal pharmacologic interventions are recommended for the treatment of hot flashes in breast cancer survivors. Antidepressants and gabapentin have been shown to be both effective and well tolerated; however, it is not clear which is preferred.

Patients and Methods

This was a group-sequential, open-label, randomized, cross-over trial of 4 weeks of venlafaxine (37.5 mg daily for 7 days followed by 75 mg daily for 21 days) versus gabapentin (300 mg once per day for 3 days, then 300 mg twice per day for 3 days, then 300 mg three times per day for 22 days), with patient preference as the primary outcome. Postmenopausal women with at least 14 bothersome hot flashes per week for the prior month were eligible. A 2-week baseline period and a 2-week tapering/washout time was used before the first and second treatment periods, respectively. Diaries were used to measure hot flashes and potential toxicities throughout the study. Participants completed a preference questionnaire at the end of the study. A predefined Pocock stopping rule was applied. Patient preference and hot flash and toxicity outcomes were compared between treatments.

Results

Sixty-six patients were randomly assigned, 56 of whom provided a preference (eight dropped out and two had no preference); 18 (32%) preferred gabapentin and 38 (68%) preferred venlafaxine (P = .01). Both agents reduced hot flash scores to a similar extent (66% reduction). Venlafaxine was associated with increased nausea, appetite loss, constipation, and reduced negative mood changes compared with gabapentin, whereas gabapentin was associated with increased dizziness and appetite compared with venlafaxine (all P < .05).

Conclusion

Breast cancer survivors prefer venlafaxine over gabapentin for treating hot flashes.

Past recreational physical activity, body size, and all-cause mortality following breast cancer diagnosis: results from the Breast Cancer Family Registry

Few studies have considered the joint association of body mass index (BMI) and physical activity, two modifiable factors, with all-cause mortality after breast cancer diagnosis. Women diagnosed with invasive breast cancer (n = 4,153) between 1991 and 2000 were enrolled in the Breast Cancer Family Registry through population-based sampling in Northern California, USA; Ontario, Canada; and Melbourne and Sydney, Australia. During a median follow-up of 7.8 years, 725 deaths occurred. Baseline questionnaires assessed moderate and vigorous recreational physical activity and BMI prior to diagnosis. Associations with all-cause mortality were assessed using Cox proportional hazards regression, adjusting for established prognostic factors. Compared with no physical activity, any recreational activity during the 3 years prior to diagnosis was associated with a 34% lower risk of death [hazard ratio (HR) = 0.66, 95% confidence interval (CI): 0.51-0.85] for women with estrogen receptor (ER)-positive tumors, but not those with ER-negative tumors; this association did not appear to differ by race/ethnicity or BMI. Lifetime physical activity was not associated with all-cause mortality. BMI was positively associated with all-cause mortality for women diagnosed at age > or =50 years with ER-positive tumors (compared with normal-weight women, HR for overweight = 1.39, 95% CI: 0.90-2.15; HR for obese = 1.77, 95% CI: 1.11-2.82). BMI associations did not appear to differ by race/ethnicity. Our findings suggest that physical activity and BMI exert independent effects on overall mortality after breast cancer.

Abstract CN05-03: Energy balance in cancer patients: Are we ready to intervene?

There is growing evidence that aspects of energy balance, including overweight/obesity and physical inactivity are associated with poor outcomes in some cancers, notably breast and colorectal. In breast cancer, evidence is strongest for overweight/obesity; recent evidence suggests physical activity may have important independent associations with outcomes. In colorectal cancer, evidence is strongest for physical activity. Clinical mechanisms that have been postulated for these associations include presentation of cancer at a more advanced stage or receipt of less than optimal therapy in overweight or obese individuals. Potential biologic mechanisms have included sex hormones, insulin and related IGFs, adipocytokines and inflammatory markers. In breast cancer there is growing evidence that insulin (and associated insulin resistance) may play a key role in mediating these prognostic associations - high insulin levels have been associated with increased risk of breast cancer recurrence or death. Breast cancer cells commonly overexpress insulin receptors (frequently a fetal form of the receptor that may hybridize with the IGF-1 receptor) that are not downregulated by circulating insulin; as a result, cancer cell growth may be stimulated by high circulating insulin levels. Observational clinical studies linking energy balance to prognosis of breast and colorectal cancer will be reviewed, along with early intervention work demonstrating the feasibility, short-term benefits (e.g. on QOL) and biologic (mechanistic) changes associated with lifestyle interventions in breast and colon cancer survivors. The impact of the available evidence on clinical practice and the role of large scale clinical trials of energy balance modification with recurrence or survival endpoints (completed, ongoing and planned) will be reviewed, with an emphasis on issues relating to feasibility, cost and the need for embedded correlative research to investigate biologic mechanisms for any survival effects that are identified. Related metformin trials (which target insulin and AMPK/mTOR signaling), notably NCIC MA.32, an adjuvant trial in early breast cancer that will be activated early in 2010, will also be reviewed.

Citation Information: Cancer Prev Res 2010;3(1 Suppl):CN05-03.