Cancers Linked to Weight
Below are some key cancers that have been linked to weight:
Obesity has been shown in many studies to raise the risk of both colon cancer and adenomatous polyps, which are precancerous growths that can turn into cancer. It’s not exactly clear how weight increases risk. One possibility is that extra weight increases insulin levels in the blood, which may then stimulate abnormal cell growth in the colon.
For the past three decades, study after study has shown that the more a woman weighs, the greater her risk of endometrial cancer. The likely reason is that overweight women tend to have higher levels of estrogen and lower levels of progesterone than lean women do. The combination of high estrogen and low progesterone has been linked to endometrial cancer.
Almost every study that’s looked at the link between weight and kidney cancer has found that obesity increases the risk of the disease. Because the link is usually stronger in women than men, being overweight may increase risk by way of hormonal changes. But scientists need to look at the issue more closely to be sure.
The esophagus is the tube that carries food down the throat and into the stomach, and there is a great deal of evidence that obesity raises the risk a specific type of esophageal cancer called adenocarcinoma of the esophagus. It’s not exactly clear why, but there’s a chance it’s related to gastric reflux, where stomach acids leak up and irritate the esophagus. Gastric reflux is an established risk factor for adenocarcinoma, and it may be more common in obese adults.
Many studies have found that weight gain can greatly increase the risk of breast cancer in postmenopausal women. Surprisingly, the opposite is true in premenopausal women: As weight increases, the risk of breast cancer decreases. Of course, this doesn’t mean that women shouldn’t watch their weight throughout life. Most breast cancers develop after menopause. And for most women, the weight they put on before menopause will likely stay with them after menopause, where it can begin to increase risk.
Weight gain likely increases breast cancer risk by raising levels of the hormone estrogen, which can promote cancer growth. After menopause, when a woman’s ovaries stop producing as much estrogen, fat tissue becomes a major source of the hormone. The more weight a woman has gained, the greater the source of estrogen after menopause.
In addition to the five cancers above, there’s also good evidence that weight gain and obesity increase the risk of pancreatic cancer, gallbladder cancer and liver cancer as well as leukemia, lymphoma and multiple myeloma.