Table 2.
Strength of the Evidence for a Cancer-Preventive Effect of the Absence of Excess Body Fatness, According to Cancer Site or Type.*
| Cancer Site or Type | Strength of the Evidence in Humans† | Relative Risk of the Highest BMI Category Evaluated versus Normal BMI (95% CI)‡ |
|---|---|---|
| Esophagus: adenocarcinoma | Sufficient | 4.8 (3.0–7.7) |
| Gastric cardia | Sufficient | 1.8 (1.3–2.5) |
| Colon and rectum | Sufficient | 1.3 (1.3–1.4) |
| Liver | Sufficient | 1.8 (1.6–2.1) |
| Gallbladder | Sufficient | 1.3 (1.2–1.4) |
| Pancreas | Sufficient | 1.5 (1.2–1.8) |
| Breast: postmenopausal | Sufficient | 1.1 (1.1–1.2)§ |
| Corpus uteri | Sufficient | 7.1 (6.3–8.1) |
| Ovary | Sufficient | 1.1 (1.1–1.2) |
| Kidney: renal-cell | Sufficient | 1.8 (1.7–1.9) |
| Meningioma | Sufficient | 1.5 (1.3–1.8) |
| Thyroid | Sufficient | 1.1 (1.0–1.1)§ |
| Multiple myeloma | Sufficient | 1.5 (1.2–2.0) |
| Male breast cancer | Limited | NA |
| Fatal prostate cancer | Limited | NA |
| Diffuse large B-cell lymphoma | Limited | NA |
| Esophagus: squamous-cell carcinoma | Inadequate | NA |
| Gastric noncardia | Inadequate | NA |
| Extrahepatic biliary tract | Inadequate | NA |
| Lung | Inadequate | NA |
| Skin: cutaneous melanoma | Inadequate | NA |
| Testis | Inadequate | NA |
| Urinary bladder | Inadequate | NA |
| Brain or spinal cord: glioma | Inadequate | NA |
BMI denotes body-mass index, CI confidence interval, and NA not applicable.
Sufficient evidence indicates that the International Agency for Research on Cancer Handbook Working Group considers that a preventive relationship has been established between the intervention (in this case, the absence of excess body fatness) and the risk of cancer in humans — that is, a preventive association has been observed in studies in which chance, bias, and confounding could be ruled out with confidence. Limited evidence indicates that a reduced risk of cancer is associated with the intervention for which a preventive effect is considered credible by the working group, but chance, bias, or confounding could not be ruled out with confidence. Inadequate evidence indicates that the available studies are not of sufficient quality, consistency, or statistical power to permit a conclusion regarding the presence or absence of a cancer-preventive effect of the intervention or that no data on the prevention of cancer by this intervention in humans are available. Additional information on the criteria for classification of the evidence is available at http://handbooks.iarc.fr/docs/Handbook16_Working-Procedures.PrimaryPrevention.pdf.
For cancer sites with sufficient evidence, the relative risk reported in the most recent or comprehensive meta-analysis or pooled analysis is presented. The evaluation in the previous column is based on the entire body of data available at the time of the meeting (April 5–12, 2016) and reviewed by the working group and not solely on the relative risk presented in this column. Normal BMI is defined as 18.5 to 24.9.
Shown is the relative risk per 5 BMI units.