The Impact of Obesity on Cancer Survivorship
Leslie Bernstein, Ph.D. Professor and Director, Division of Cancer Etiology Department of Population Sciences Beckman Research Institute City of Hope
Measuring obesity in studies • Body mass index (kg per m2) – WHO cut points 65 yrs at diagnosis, shows independent of smoking status (Leung et al, Int J Epidemiol 2011;40:174)
• Few studies of renal cell carcinoma (high BMI better prognosis), lymphoma and childhood ALL (high BMI poorer prognosis), etc.
Obesity and Colon Cancer Prognosis • Review of 8 studies (Parekh et al, Ann Rev Nutr 2012, epub) • 3 used pre-diagnosis measures – 15% to 2-fold increased risk for colon but not rectal cancer mortality among obese persons.
• 5 used post-diagnosis measures: results are mixed – 3 show statistically significantly increased risk among obese (includes one study also looking at pre-diagnosis BMI) – 3 show increased risk but not statistically significant elevation in risk among obese
• Sex Difference: Intergroup 0089 trial: poorer survival among obese women but not among obese men (Meyerhardt et al., Cancer 2003)
Colon Cancer – treatment difference • Two large phase III clinical trials – CAIRO 796 advanced colorectal cancer patients treated with chemotherapy – CAIRO2 – 730 advanced colorectal cancer patients treated with chemo+targeted therapy
• CAIRO: High BMI associated with longer median overall survival • CAIRO2: No association between BMI and overall survival Simkens et al, Eur J Cancer 2011;47:2560.
Obesity and Prognosis after Breast Cancer • BMI considered an established negative prognostic factor for breast cancer in premenopausal and postmenopausal women although not all studies agree • Does not matter when BMI assessed (before, at or after diagnosis) • Similar results for weight gain • Limited data on weight loss (few studies of intentional weight loss) • Few studies consider other lifestyle factors
Obesity and Prognosis after Breast Cancer • Few studies consider other lifestyle factors • Studies conducting follow-up of women in clinical trials show more modest effects • Most observational studies cannot assess recurrence (disease free survival) • Most studies are of white women
Change in Body Mass Index Pre-dx to Post-dx: Relative risk of breast cancer death: 5,204 women with breast cancer from the Nurses Health Study
Among Never Smokers
Category of BMI Change Loss
Maintain
Gain
Gain
0.5 30 (n=376)
1.2 (0.9-1.6)
Relative risk (95% CI)
Adjusted for age at diagnosis, alcohol intake, tumor size and lymph node positivity
Rosenberg et al, Br J Cancer 2009;100:1486
Obesity, Hormone Therapy Use and Prognosis after Breast Cancer in Swedish population • In etiologic studies hormone therapy interacts or competes with obesity: hormone therapy increases risk of breast cancer among normal weight and thin women Body mass index (kg/m2) No hormone therapy and number of patients
Estrogen+ progestin therapy
Relative risk (95% CI)
Relative risk (95% CI)
< 25 (n=1267)
1.0
1.0
25-30 (n=997)
0.8 (0.6-1.1)
1.0 (0.5-2.1)
>30 (n=376)
0.9 (0.6-1.3)
2.3 (1.1-5.2)
Adjusted for age at diagnosis, alcohol intake, tumor size and lymph node positivity
Rosenberg et al, Br J Cancer 2009;100:1486
Does greater obesity among Black women explain mortality disparity in breast cancer? • Women’s Contraceptive and Reproductive Experiences (CARE) Study • Population-based case-control study • 1622 black and 2953 white women with invasive breast cancer • Ages 35-64 years • Women diagnosed between 1994 and 1998 Lu et al., J Clinical Oncol, 2011
Participants Los Angeles Atlanta Detroit Seattle Philadelphia
1604 black, 2934 white women
Median yrs of follow-up: 8.6 yrs (25th-75th percentiles: 7.1-10.1 yrs)
In-person interviews
•
• Height Weight 5 yrs before diagnosis • Demographic factors • Tumor characteristics
Lu et al., J Clinical Oncol, 2011
Deaths: 519 black, 534 white
breast cancer deaths 412 black, 416 white
Relative risk (95% CI) of mortality
Results: BMI at 5 years before diagnosis and mortality 1.6 1.4 1.2
