Fresh evidence links adiposity with multiple cancers
A partir d'une revue systématique des méta-analyses (204 articles identifiés), cette étude fait le point sur l'association entre l'adiposité, le risque de développer divers types de cancers, et le risque de décès par cancer
The association is now clear; it’s time to get serious about prevention The International Agency for Research on Cancer (IARC) working group recently reviewed epidemiological data, studies in experimental animals, and mechanistic data and concluded that excess body fatness causes cancer of the colon and rectum, liver, gallbladder, pancreas, kidney, thyroid, breast (postmenopausal), endometrium, ovary, oesophagus (adenocarcinoma), and gastric cardia, as well as meningioma and multiple myeloma.1 This potentially makes excess body fat the second most important modifiable cancer risk factor after tobacco use. The study by Kyrgiou and colleagues2 took up the challenge of evaluating the robustness of multiple, sometimes overlapping, meta-analyses that reported an association between body adiposity measures (such as body mass index, weight gain, and waist circumference) and cancer. The authors conducted an umbrella review, also known as a “review of reviews” or “meta-review,”34 and initially identified a total of 204 individual meta-analyses from 49 papers. They further examined the 95 meta-analyses that reported the association between body fatness measured on a continuous scale (mostly body mass index in 5 kg/m2 increase) and cancer in cohort studies. After a rigorous evaluation for strength and validity of reported associations, 13% (12 of 95) of meta-analyses were judged to provide strong evidence on the basis of their statistical criteria. The rest of the meta-analyses were deemed to be highly suggestive (18%), suggestive (25%), and weak (20%). Twenty four per cent of meta-analyses found no association between body fatness and cancer. Nine obesity related cancers were supported by strong evidence: oesophageal adenocarcinoma, colon and rectal cancer (in men), biliary tract system, pancreatic, and kidney cancer, endometrial cancer (premenopausal women), breast cancer (postmenopausal), and multiple myeloma. A positive association between body mass index and liver, ovarian, or thyroid cancer was highly suggestive or suggestive; a negative association with oesophageal squamous cell carcinoma or lung cancer was highly suggestive. In additional analyses using obesity categories (obesity versus normal weight), strong evidence also supported increased risks of gastric cardia and ovarian cancer in obese individuals. Both the IARC report and Kyrgiou and colleagues’ umbrella review consistently and strongly concluded that excess body fat increases the risk of most digestive system cancers as well as endometrial and postmenopausal breast cancer. However, for gastric cardia, and cancers of the liver, ovary, or thyroid, the strength of evidence differed between the two approaches, which can be explained by differences in the method used to summarise the evidence. (...)