Why Obesity Could Be To Blame For Rise In Cancer Rates

There is a lot to celebrate in the battle against cancer. Research by the American Cancer Society shows that the U.S. death rate from cancer fell by 29 percent from 1991 to 2017. Much of the decline is due to less smoking, as well as better screening and treatment of cancer.

But a disturbing trend lurks beneath the good news. The ACS also found that rates of cancer linked to obesity are rising among adults under 50. Even more alarming, the younger the generation, the greater the risk of developing certain cancers.

Dr. Neil Iyengar, a medical oncologist at Memorial Sloan Kettering Cancer Center who cares for people with breast cancer, is a leading researcher on the relationship between diet and exercise, metabolism, obesity and cancer. He answered questions about this rise in cancer among younger adults.

What does ACS research tell us about obesity and cancer?

The link between obesity and cancer is already well-established, but these data are mostly from older people. Obesity rates are accelerating in young people. The ACS findings suggest that obesity among young adults is also driving up their rates of cancer, including colorectal cancer, pancreatic cancer, kidney cancer, gallbladder cancer, uterine cancer and multiple myeloma. These cancers are often not discovered in younger people until the disease is advanced, when it's harder to treat.

What happens if this trend continues?

This research could be a warning. People's risk of cancer typically rises as they age. So these young people at higher risk because of obesity could face even greater risk as they grow older.

Currently, one in six cancer deaths in men and one in seven cancer deaths in women are accelerated by obesity. Those numbers could get worse. Obesity might chip away at some of the gains that have been made in reducing the death rate from cancer.

How does obesity lead to cancer?

Fat is an active tissue — it doesn't just sit there. It can become dysfunctional, resulting in inflammation, which increases the risk of developing cancer. Many of the cancers linked to obesity are in organs that are surrounded by pads of fat.

In addition, excess fat can influence the whole body. For instance, people with dysfunctional fat tissue often have altered levels of hormones such as insulin and estrogen in their blood. These changes can damage DNA and lead to several cancers.

What about people who are not obese?

People who are not obese need to be careful, too. Research at MSK and elsewhere suggests that having too much fat — even if you have a normal body weight or body mass index — can increase the risk of developing cancer and heart disease.

The alarming findings we have seen about cancer among younger people underscore that it’s never too early to start good eating and exercise patterns.

What can be done about the rise of obesity-related cancer?

We need to start thinking of some foods and high-sugar beverages in a similar way that we think about tobacco: unnecessary, addictive and harmful. It speaks volumes that obesity is expected to overtake smoking as the number one preventable cause of cancer.

Public health campaigns have run for decades telling young people that if you smoke now, you’ll have serious problems later with heart and lung disease and cancer. The falling rates of smoking suggest that people are now paying attention. The public needs a similar message for obesity: High amounts of body fat can lead to major health problems, including cancer. We can act now to help reduce that risk.

Learn more about MSK's outpatient cancer centers in Nassau, Commack and Hauppauge at mskcc.org/longisland.