Obesity causes 32,000 cancer deaths in the UK each year, and research by academics at Haver University suggests that in about 10 years, obesity will overtake smoking as the most serious cancer-causing factor. About 500,000 cancer cases are caused by obesity every year. Obesity increases the incidence of cancer on one side, and some of the most common cancers are affected by obesity 20 years earlier than before, such as bowel cancer. Obesity has been shown to be closely related to the following cancers: colon cancer, breast cancer, endometrial cancer, kidney cancer, esophageal cancer, as well as gallbladder, ovarian and pancreatic cancer, in addition to overweight root thyroid cancer. In addition, excessive weight is associated with thyroid cancer. A study published in LANCET in 2010 showed that for every 15 kg increase in body weight in men, the chance of developing esophageal cancer increased by 52%, thyroid cancer by 33% and colon and kidney cancer by 24%. In women, a 13 kg increase in body weight is associated with a 24% increase in the incidence of endometrial and gallbladder cancers and a 51% increase in the incidence of esophageal cancer. With the improvement of living standard, the waistline of Chinese people becomes thicker and thicker. Data show that from 1985 to 2012, the waist circumference of Chinese men rose by more than 15%; from 2002 to 2010, the proportion of overweight and obese Chinese adults rose from 25% to 38.5%. According to the World Health Organization forecast, by 2015, more than half of China’s population will be overweight, and the Chinese obesity is mainly abdominal obesity, which is more harmful. British researchers conducted a 7 and a half year long follow-up survey, the selection of the target is the age of 16 years and above, and a total of 5.24 million people were surveyed, during which a total of 166,955 people were found to have cancer. Danish researchers found after 11 years of follow-up study on 44,000 people that obese people have an increased likelihood of esophageal cancer, liver cancer and pancreatic cancer, and certain endocrine-related cancers, such as endometrial cancer, certain Certain endocrine-related cancers, such as endometrial cancer, certain gastrointestinal tumors, and kidney cancer, have an increased RR in obese women. The Karolinska Institute, a leading Swedish institution, examined more than 28,000 hospital patients from 1965 to 1993. As a result of the study, it was found that 33% of cancers occurred in obese people, of which the percentage was 25% in men and 37% in women. They also recognized that obese people have a higher chance of developing small bowel cancer, colon cancer, gallbladder cancer, pancreatic cancer, laryngeal cancer, kidney cancer, bladder cancer, cervical cancer, uterine cancer, ovarian cancer, brain tumors, connective tissue tumors, and lymphoma than the general population. In addition, obese men have a higher rate of lymphogranulomatous disease than obese women have a higher rate of non-Hodgkin’s lymphoma than the general population. Some of the causes are direct and some are indirect. The fact that fat cells, like many cells in the body, release hormones and certain hormones that increase the risk of certain cancers is a direct link. Another example is that these cells also produce growth factors that can increase the rate of tumor growth. We also see that people with obesity have chronic low levels of inflammation, and inflammation may also increase the risk of cancer. There are also difficulties in treating cancer in obese patients, even suggesting that obesity is one of the factors influencing tumor prognosis, and obese colon cancer often suggests a poor prognosis, while ASCO guidelines published in 2014 mention that only 1 in 10 Americans recognize the impact of obesity on tumors. And about 40% of obese patients have low drug doses during treatment and do not achieve optimal outcomes. Therefore, obese cancer patients need to increase the drug dose of chemotherapy. The possible mechanism of obesity causing cancer is not very clear, there are speculations as follows: excess fat and the formation of obese cells will promote high levels of insulin and estrogen (estrogen, hormone) secretion, accelerating the growth and division of cells, but also increase the growth and formation of abnormal cells cancer cells. In addition, adipose tissue can effectively accumulate carcinogens and hinder their metabolism and emission, which is the main cause of cancer tumors. An oncologist once pointed out: “If a tumor is a growing plant, then fat is its catalyst. Of course, inflammatory response is also one of the causes of cancer, and obesity is an inflammatory disease. The close relationship between obesity and cancer has received widespread attention. 2014 data show that the risk of breast cancer among Shanghai women enters a more frequent period after the age of 45, and in the past 10 years, it also shows a slight decrease in incidence before the age of 45 and a significant increase after the age of 45, with the increase in the age of 60-74 being 10 percentage points greater than that of 45-59. Zheng Ying pointed out that the age of 60-74 is a critical period for postmenopausal breast cancer prevention and treatment. It is generally accepted in academia that there is a 10-year lag period for cancer development due to overweight and obesity. Therefore, in order to reduce the incidence of breast cancer, one should lose weight at least 10 years earlier. Therefore, for patients with severe obesity, early weight loss can reduce the incidence of cancer.