Importance of Weight Loss in Preventing Cancer For Diabetes Patients

Weight loss is a significant lifestyle modification that can affect both diabetes and the risk for some types of cancer. 

In the Look AHEAD randomized clinical trial, the study analyzed the effect of intensive weight loss intervention on lowering cancer occurrence and mortality. Other observational studies showed that reducing weight in patients at risk of cancer lowers their chances of being diagnosed with cancer. These studies included women with postmenopausal breast cancer; the correlation of obesity and risk of obesity-related cancer showed a reduction in cancer risk with weight loss. The study’s purpose was to have a larger population size to study overweight/obesity patients with type 2 diabetes using intensive lifestyle intervention of weight loss related to reducing cancer risk.  

The study’s objective was to look at the results in the high-risk population of type 2 diabetes adults. It is a randomized controlled trial where patients are randomized into two study arms. Participants were assigned to either intensive lifestyle intervention (ILE) or diabetes support and education (DSE) arms. The ILE group intervention maintained a weight loss of at least 7% using a reduced caloric intake and increased physical activity. The DSE group intervention was diet, exercise, and social support.   

Cancer incidence was one of the outcomes; reported at the first sign of malignant tumor, except for nonmelanoma skin cancer. The primary analysis was the association of ILI cancer incidence, obesity-related cancer events, and cancer mortality. Secondary endpoints consisted of site-specific cancer incidence.   

The statistical tests used were the Kaplan-Meier (cumulative cancer incidence and cancer mortality), Cox proportional hazard models (calculate hazard ratio), Post hoc analysis to determine heterogeneity. The Fine and Gray method was used for the sensitivity analysis of the overall cancer incidence and obesity-related cancer incidence.   

The intensive lifestyle intervention group showed the most significant weight reduction compared to the diabetes education support group.  After the 12-year follow-up, the average weight loss was 6.84 kg in the ILI group and 4.87 kg in the DSE group.  ILI intervention group showed a weight loss that lowered the incidence of obesity-related cancers by 16% in the adults that had overweight or obesity with type 2 diabetes. Three hundred thirty-two patients in the ILI group, compared to three hundred fifty-two in the DSE group, were diagnosed with cancer. The obesity-related cancer incidence rates were 6.1 and 7.3 per 1,000 person-years in ILI and DSE, respectively, with an HR, 0.84; 95% CI: 0.68-1.04.  Cancer incidents for obesity-related cancers: DSE number of events 185, compared to ILE number of occurrences of 158 with an HR 0.84 (0.68-1.04), P-value 0.10.  

The obesity-related cancer mortality number of DSE events was 45 compared to ILI events of 42 with HR 0.9 (0.60-1.39); the P-value of 0.67.  Eighty participants died of cancer in the ILI group and 85 in the DSE group with HR 0.92; 95% CI: 0.68-1.25.  

To conclude, the intensive lifestyle intervention arm’s results had no association with a substantial reduction in the overall cancer incidence nor cancer mortality, but did show a lowered incidence of obesity-related cancers and reduced weight loss than the diabetes education support group. Obesity patients do have a chance to reduce their cancer risk with intensive weight loss.  

With weight loss being an essential factor in managing type 2 diabetes, it is vital to study the effect of weight loss on reducing cancer risk in obesity. Limitations of this study included: being limited to only adults with type 2 diabetes, high BMI at baseline, the site-specific cancers were insufficient. Future studies need to have enough power for the outcomes.   

Practice Pearls: 

• Patients with type 2 diabetes and overweight or obesity have a chance to reduce their cancer risk with weight loss intervention. 
• Obesity-related cancer incidence is seen with type 2 diabetes and must be monitored to prevent cancer risks. 
• Educating patients on weight loss management and managing diabetes will help to provide a better quality of life. 

HC Yeh, JP Bantle, M Cassidy-Begay et al. Intensive Weight Loss Intervention and Cancer Risk in Adults With Type 2 Diabetes:  Analysis of the Look AHEAD Randomized Clinical Trial. Obesity 2020Sep01.  

Tarshay Boyd, PharmD. Candidate, LECOM School of Pharmacy