While the correlation between cancer and obesity has been long noted, the American Society of Clinical Oncology (ASCO) has now called for the link to be officially recognized. Obesity is quickly overtaking tobacco as the leading preventable cause of cancer, but only about 10 percent of Americans are aware of this. Oncologists have now been called to inform patients that obesity is not only a factor in cancer diagnosis, but also linked to cancer’s recurrence and mortality rates.

Obesity is a drastically under-recognized contributor to America’s cancer toll. The National Cancer Institute estimates that as many as 84,000 cancer diagnoses each year are related to extra body mass. The correlation doesn’t just stop with cancer diagnosis. Fat is connected to cancer every step of the way. According to Clinical Endocrinology News, obesity can interfere with the delivery of cancer therapy and is linked to higher recurrence of cancer. A study from 2003 followed 900,000 American adults for 16 years and found that the heaviest participants were not only more likely to develop cancer, but extra fat also "could account for 14 percent of all deaths from cancer in men and 20 percent of those in women," CNN reported.

The precise reason for cancer being so closely linked to extra body weight is not completely understood, but experts believe it has something to do with obesity causing the body to operate differently. This abnormal bodily function can cause harmful cell growth and cell division, CNN reported. To better explain this, Dr. Clifford Hudis, an oncologist at Memorial Sloan Kettering presented CNN with breast cancer as an example.

It has been found that premenopausal women who were obese at the time of breast cancer diagnosis were 75 percent more like to succumb to the disease than normal-weight patients. Hudis explained that obesity can cause chronic inflammation, which in turn can lead to an increase in the production of estrogen. In the case of breast cancer, estrogen has been identified as a factor in the development of breast cancer tumors.

For those who are currently overweight or even obese, there is hope. As with smoking, obesity is a preventable cancer factor, meaning that it can be avoided. The ASCO hopes that announcing cancer as a significant cancer risk will encourage more individuals to make serious lifestyle changes.

Even oncologists aren’t exempt from this call to slim down, with the ASCO asking that doctors of cancer patients lead by example in order to share personal weight loss stories with their clients. The ASCO has even created a toolkit to provide patients and doctors with weight loss strategies and tips, hopefully to “reinforce the importance of health lifestyle behaviors as part of a comprehensive cancer-control strategy,” the statement said.