New Delhi, Apr 21 (IANS): Obesity leads to 13 types of cancer, including that of pancreas and esophagus, as fat cells affect the processes that regulate the growth of cancer cells in the human body, says a study.

Due to excess fat in the body, fat cells produce hormones and proteins, according to the study conducted by the United Kingdom's Imperial College.

Besides being released into the bloodstream, these are also circulated around the body and this is why they increase the risk of several different types of cancer.

Fat cells are also said to affect processes that regulate cancer cells' growth.

According to the World Health Organisation (WHO), around 1.9 billion adults worldwide are overweight or obese, and with obesity linked to some 13 types of cancer, the problem of extra weight poses a serious threat to their lives.

Among the 13 types of cancer, which are believed to have strong connection with weight gain, are oesophageal (food pipe), pancreatic, liver, stomach, colon and rectum, gallbladder, lung, kidney and gynaecological cancer. Among women, breast, ovary or uterus cancer could occur.

"The most common types include breast and colon, while the most difficult to treat include pancreatic, oesophageal and gallbladder cancer," said the study.

Commenting on the study, Deep Goel, Director of Bariatric and Gastrointestinal Oncology Surgery at the BLK Super Speciality Hospital, said that obese had a greater risk of developing and also dying from several types of cancer.

"Let's say, if there's one normal-weight patient suffering from pancreatic cancer and another obese patient suffering from the same cancer of same stage, chances of an obese patient's death are more over normal-weight patient," said Goyal.

Stating that insulin is a very important part of how the body uses energy from food, Goyal said: "When people are obese, the level of insulin increases in the body which may help cancer cells to develop. Moreover, fat accumulated in the body changes the levels of sex hormones -- oestrogen and testosterone, which again increases the risk of cancer."