The findings are based on analysis of more than 200 previous studies which included over 250,000 cases of cancer performed by Dr. Andrew Renehan and colleagues from the University of Manchester and Christie Hospital. The study included patients from North America, Europe, Australia, and the Asia-Pacific region. The researchers' work centered on understanding what the risk for cancer was in patients who had an increase in body mass index of 5 kg/m2 (weight/height), equivalent to roughly 11 lbs/3.28 ft2.
What they found was that a BMI increase of 5 kg/m2 in men increased risk for esophageal adenocarcinoma by 52%, for thyroid cancer by 33%, and for both colon and kidney cancer by 24%. The threat of rectal cancer and malignant melanoma also increased, though by less significant numbers.
For women the increased risk was even higher: a BMI increase of 5kg/m2 translated into a 59% increased risk of both endometrial and gall bladder cancer, a 51% increase in endometrial cancer risk, and a 34% increase in kidney cancer risk. The study also found increased risk among women for postmenopausal breast, pancreatic, thyroid, and colon cancers in accordance with an increase in BMI.
Obesity is currently linked to 20% of all annual cancer-related deaths in women and 14% in men, compared to 30% of cancer deaths in both sexes linked to smoking. The rise in non-smoker cancer rates has been both dramatic and unexpected. Medical studies in the 1980s failed to produce a link between obesity and cancer; that trend has sadly been identified in the wake of the global obesity epidemic.
The occurrence of leukemia, various forms of myeloma, and non-Hodgkin's lymphoma also increased in both women and men, though women seemed to suffer from colon cancer at a far lower rate even if they had achieved a similar increase in BMI: 9% for women versus 24% for men.
Dr. Andrew Renehan observes, "This was a hugely comprehensive piece of research looking at 221 different studies in 20 types of cancer. For some cancer types, associations differ between sexes and populations of different ethnic origins, and this should inform the exploration of biological mechanisms that link obesity with cancer."
He adds, "Over the past five years, there has been increasing proof that obesity is linked with cancer risk, but despite this, we do not know whether weight reduction in people protects them against cancer. The findings of this study are important to address these issues and explore ways to prevent cancers in the future."
The best thing to do in this age of genetically engineered and nutritionally bankrupt mass-produced foods may be to relearn how and what to eat; with almost a full third of cancers now linked to dietary and nutritional factors, it would be self-destructive to do otherwise.
