Excess Weight at Diagnosis Ups Risk of Second Cancer

Older people who had excess weight or obesity when diagnosed with a first non-metastatic cancer had a higher risk of developing a second cancer, according to a study.

Non-metastatic cancer is cancer that hasn’t spread to parts of the body away from the area where it developed. 

The researchers analyzed information from nearly 27,000 people in the Cancer Prevention Study II Nutrition cohort who were diagnosed with a first non-metastatic cancer between 1992 and 2015. Overall, 43% had excess weight (BMI of 25-29.9) and 17% had obesity (BMI of 30 or higher) when first diagnosed. The average age at first diagnosis was 72, and about 19% of the people in the study were diagnosed with breast cancer. 

The people in the study were followed until 2017.

During follow-up, 14% of the people were diagnosed with a second cancer; 33% of these were considered obesity-related cancers, which include breast, colon, kidney, and ovarian cancers. Compared to people who didn’t have excess weight or obesity, people who had excess weight had a 15% higher risk of developing a second cancer and people who had obesity had a 34% higher risk.

For obesity-related cancers, the increase in risk was higher. People who had excess weight had a 40% higher risk of developing a second obesity-related cancer and people who had obesity had a 78% higher risk.

“We know that excess body weight is associated with adverse outcomes [among] cancer survivors,” lead author Clara Bodelon, PhD, MS, said in an interview. “That includes increased risk for diseases such as diabetes or heart disease. 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.”

Bodelon is senior principal scientist in survivorship research at the American Cancer Society.

“Excess body weight is a modifiable risk factor, and weight loss to reach a healthy

body weight among cancer survivors may result in substantial health and quality of life benefits,” the researchers wrote. “Older survivors may face unique challenges to achieve dietary or physical activity goals needed to reach or maintain a healthy weight, due to physical, physiological, and metabolic changes. A personalized weight management plan, which may include a nutrition plan, and a physical activity regimen that is shared with an interdisciplinary care team to ensure adequate social support and additional resources may result in long-term healthy behaviors.”

“While improvements in cancer treatment undoubtedly have contributed to longer life expectancies in individuals with cancer, it is equally, if not more, important that we invest in obesity prevention and efforts to improve the quality of life of cancer survivors,” Cari Kitahara, PhD, wrote in an invited commentary that accompanied the article. “If current obesity and cancer incidence trends continue, we should expect a substantial increase in the number of cancer survivors experiencing obesity-related health outcomes …”

Dr. Kitahara is an epidemiologist and senior investigator at the U.S. National Cancer Institute.