Philip J. Goscienski, M.D.
July 2010
The obesity and overweight that affect more than two thirds of our population have emerged as major causes of cancer and they are about to overtake tobacco use as the main preventable cause of a disease that so many people fear. Whereas smokers' major concern is lung cancer, obesity leads to several types of cancer and for a variety of reasons.
Back in the days when Americans were lean and active, as in the earliest decades of the last century, there was no apparent association between being overweight and developing cancer. Infectious diseases led the causes of death and persons who did develop cancer succumbed rather quickly. Chemotherapy, radiation therapy, antibiotics and advanced surgical techniques were decades away for the relatively few persons who developed malignant tumors.
Few cancers have a single cause. They afflict the slender as well as the corpulent but obesity is increasingly linked to cancer of the uterus, esophagus, breast, pancreas, kidney, gallbladder and liver. Current evidence suggests that obesity accounts for about 20 percent of cancer deaths in women and about 14 percent in men. The obesity epidemic might be slowing down a little but the prediction that 80 percent of Americans will be overweight by the middle of the coming decade makes it likely that the cancer rate will also increase.
Fat cells produce estrogen, a hormone that increases the risk of uterine and breast cancer, especially after the onset of menopause. As the amount of fat increases, so does the risk of both types of cancer. For obese women the risk of cancer involving the lining of the uterus is nearly 3 ½ times that for women of normal weight.
As body fat increases so does the risk of type 2 diabetes. In its early stages that disease is characterized by high levels of circulating insulin. In addition to helping the body regulate blood sugar levels, insulin encourages cells to grow. If those cells are cancerous they seem to grow faster, outstripping the body's immune system that ordinarily keeps them in check. Cells of the colon are especially responsive to the growth-promoting effects of insulin, perhaps explaining why it kills more non-smokers than any other type of cancer.
It's far easier to prevent weight gain than it is to lose weight, which makes it so important to teach our children how to develop good lifestyle habits. Let's not allow cancer to be another epidemic.
Philip J. Goscienski, M.D. is the author of Health Secrets of the Stone Age, Better Life Publishers 2005. Contact him at drphil@stoneagedoc.com.