Obesity and cancer

The association between obesity, as defined by a body mass index of 30 or higher, and risk of a variety of types of cancer has received a considerable amount of attention in recent years.

Obesity appears to be the third most important risk factor for cancer in the United States, just behind tobacco and diet (see Figure).

[5][6][7] In 2018, Chinese researchers performed a systematic review and comprehensive quantitative meta‐analysis of cohort studies reporting body mass index (BMI) and the risk of 23 cancer types, providing epidemiological evidence supporting the association between BMI and cancer risk.

The strongest positive association between BMI and cancer risk was found among patients in North America.

[9] Adipose tissue also creates an inflammatory environment that enhances the ability of tumor cells to metastatize.

[11] Articles supporting this view were reviewed by Cerda et al.[12] There are also a number of hormonal, metabolic and other changes caused by obesity that may affect carcinogenesis.

[11] A review by Tahergorabi et al. summarizes articles indicating that obesity induces changes in angiogenesis, inflammation, interaction of proinflammatory cytokines, endocrine hormones, adipokines including leptin and adiponectin, insulin, growth factors, estrogen, progesterone and cell metabolism.

The level of 8-oxodG correlated positively with body mass, BMI, hip circumference and triglyceride concentration.

[33] Obese people are at a higher risk of thyroid cancer than are their normal weight counterparts.