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Overweight can give you cancer

By Flavia Nassaka

Experts say there would be 12,000 fewer cancer cases globally if people were normal weight

Ugandans need to change their social attitudes that make being overweight seem harmless, if not even attractive.

Dr. James Kafeero, an expert on tumors at the Uganda Cancer Institute in Kampala says overweight people often have increased levels of insulin in their blood (a condition known as insulin resistance), which may promote the development of certain tumors.

He adds that obese people often have chronic low-level inflammation, which has been associated with increased cancer risk.


Dr. Kafeero was reacting to a recent study of around 12, 000 cancer cases recorded a year that have a link to being overweight or obese, according to a study published in the Lancet medical journal.

Released this August, the study involved data from five million UK adults being monitored for a period of seven years. It found that excess weight is linked to 10 different cancers, including cervical cancer, breast cancer and leukemia.

The strongest links were in cancer of the womb, where excess weight was responsible for 41% of cases and in gallbladder, kidney, liver, and colon cancers, where it caused 10% or more.

Over 250 patients are admitted to the Uganda Cancer Institute (UCI) a month.

According to Christine Namulindwa, the Institute’s spokesperson, more than 30 new patients are received daily in addition to over 1000 outpatients already being treated by the institute.

The Uganda Heart Institute also predicts that obesity-related heart disease could become a leading cause of death in the country by 2020.  Worldwide, an estimated one billion people are overweight, compared to 800 million who are undernourished.

Until now, over weight has been implicated in the increased cases of diabetes and cardiovascular diseases. New evidence emerging, however, suggest it could have myriad other effects; including causing cancer.

Cancers have many causes, some of them genetic and environmental. But the researchers, from the London School of Hygiene and Tropical Medicine (LSHTM) took into account all the other factors involved in order to come up with a good estimate of the actual number of cancers that could be prevented if people kept to a normal weight.

“If we could magically remove excess weight from the population, we would have 12,000 fewer cancers,” said study leader Dr Krishnan Bhaskaran, in a statement. He said that team members were surprised at the strength of the results. “The number of people who are overweight or obese is rapidly increasing both in the UK and worldwide. Our results show that if these trends continue, we can also expect to see substantially more cancers as a result.”

The researchers looked at data from five million individuals over the age of 16, which included details of height and weight, from which they could calculate their body mass index (BMI) in kgs used to indicate whether or not people are overweight. They looked at the 22 most common cancers and found excess weight associated with 17 of them.

Each 5kg increase in BMI was clearly linked with higher risk of cancers of the uterus (62%), gallbladder (31%), kidney (25%), cervix (10%), thyroid (9%), and leukemia (9%). Higher BMI also increased the overall risk of liver (19%), colon (10%), ovarian (9%), and breast cancers (5%) but there were other variables.

Dr. Joyce Kambugu who is an expert in tumors in children, says several possible mechanisms could explain the association of obesity with increased risk of certain cancers.

She points out that fat tissue produces excess amounts of estrogen, high levels of which have been associated with the risk of breast and other cancers.

More than one-third of African women and a quarter of African men are estimated to be overweight, and the World Health Organization predicts that will rise to 41% and 30% respectively in the next 10 years.

According to Dr. Kafeero, this is brought about by the kind of lifestyle that people; especially those in the cities embrace including eating deeply fried foods.

“In the cities, people encounter a new world of less energy-demanding jobs and a plentiful supply of fried, cheap meats laden with fats”, he said, “People were used to large amounts of physical labour and walking as well as an abundance of fruits and healthy grains to eat.”

To reduce cancers linked to overweight, the doctor recommends reduction of caloric intake by taking less sugar sweetened beverages and junk food. He says, for some overweight people, the body breaks the fat and turns it into oestrogen hormones which make cancers aggressive. He also recommends physical exercise.

Dr. Kafeero says medics have difficulty curbing cancer because people report to hospital late. Up to 44% turn up at the institute after feeling discomfort for six months. At that point, it is always almost too late.

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