Excess body weight at first cancer diagnosis linked to second malignancy risk
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Older adult cancer survivors who were overweight or obese at the time of first primary cancer diagnosis had a higher risk for developing second cancers, according to findings presented at ASCO Annual Meeting.
The risk for obesity-related second cancers appeared particularly strong.
“We know that excess body weight is associated with adverse outcomes [among] cancer survivors. That includes increased risk for diseases such as diabetes or heart disease,” Clara Bodelon, PhD, MS, senior principal scientist in survivorship research at American Cancer Society, told Healio. “Our research adds to the previous information about the risk for second cancers. This information is important for clinicians, as well as patients, to be aware of.”
The analysis included data from 26,894 men and women in the Cancer Prevention Study II Nutrition cohort who had been diagnosed with a first nonmetastatic incident malignancy between 1992 and 2015. Median age at diagnosis of first cancer was 72.5 years (interquartile range, 67.7-77).
The cohort included 10,713 individuals with normal BMI (18.5 to < 25) at the time of first primary cancer diagnosis, 11,497 individuals with BMI in the overweight range (25 to < 30) and 4,684 individuals with BMI in the obesity range ( 30).
Researchers followed these individuals until 2017 for diagnosis of a second primary cancer. Outcomes of interest included any second cancers and obesity-associated second cancers, such as breast cancer or colorectal cancer.
During median follow-up of 7.5 years, 3,749 study participants had been diagnosed with a second cancer, including 1,243 obesity related second cancers.
Compared with cancer survivors who had BMI in the normal range at the time of first cancer diagnosis, those who were (HR = 1.12; 95% CI, 1.05-1.21) or obese (HR = 1.29; 95% CI, 1.18-1.42) exhibited higher risk for any second cancer.
Researchers also observed higher risks for obesity-related second cancers among those who were overweight (HR = 1.37; 95% CI, 1.2-1.57) or obese (HR = 1.6; 95% CI, 1.36-1.88) at the time of first cancer diagnosis.
Results showed particularly strong associations between obesity and elevated risk for breast cancer as a second malignancy (HR = 1.43; 95% CI, 1.03-1.98) or colorectal cancer as a second malignancy (HR = 1.91; 95% CI, 1.42.1.56).
Healio spoke with Bodelon about the findings and how oncologists can help encourage their patients and cancer survivors to maintain BMI in the normal range.
Healio: Why did you conduct this study?
Bodelon: After an initial diagnosis, patients are worried about the risk for developing a subsequent malignancy. It’s important to understand factors that affect risk for a second malignancy so we can inform cancer survivors about what is in their power to lower that risk. For this study, we were interested to look at excess body weight, which is a modifiable risk factor for second cancers.
Healio: How did you conduct this study?
Bodelon: We used data from American Cancer Society’s Cancer Prevention Study II. It is one of the largest studies in our country to study cancer risk and survivorship. Participants in this study received biennial surveys. We had a very large, rich dataset to look at body weight close to the diagnosis of the first cancer and assess how it affected the risk for a second cancer.
Healio: What did you find and why are the results important?
Bodelon: Cancer survivors with excess body weight had a significantly increased risk for second cancers and obesity-related second cancers. Obesity-related cancers — which include breast, colorectal, pancreatic or kidney cancers — are a group of 13 malignancies for which International Agency for Research on Cancer has found sufficient evidence to associate with excess body weight.
Based on our results, it’s important for cancer survivors to have a support team for the patient consisting of clinicians and nonclinicians who work together to help the patient maintain a healthy weight through coordination of nutrition and physical activity. This can be an important aspect of survivorship care.
Healio: What is next in your research?
Bodelon: We’re going to continue looking into how weight change affects risk for second cancers, as well as factors that determine excess body weight. These factors include excess energy intake, food and drink consumption, and physical inactivity. We also want to continue looking at other factors in the etiology of second cancers — especially modifiable risk factors.
References:
- American Cancer Society. Obesity at time of cancer diagnosis brings higher risk for survivors of second cancer, new study finds (press release). Available at: https://pressroom.cancer.org/ASCO24BODELON#. Published May 28, 2024. Accessed July 18, 2024.
- Bodelon C, et al. Abstract 12043. Presented at ASCO Annual Meeting; May 31-June 4, 2024; Chicago.
For more information:
Clara Bodelon, PhD, MS, can be reached at clara.bodelon@cancer.org.
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