Obesity: risk factor for cancer that varies according to sex and type of tumor

It has long been known that the obesity is a risk factor for cancer but, until now, most studies have not looked at whether that risk is the same in men and women.

A research published in Cancer Cellpoints out that both the general accumulation of fat and its distribution in different parts of the body change the risks of cancer according to the sex of the patient.

In addition, the study found that the risks also vary depending on the type of cancer, such as colorectal, esophageal, and liver.

“An important aspect of the disease risk associated with obesity is the distribution of fat in different compartments of the body”explains the study’s lead author Åsa Johansson, a researcher at Uppsala University (Sweden).

The authors wanted to perform a gender-stratified analysis of adiposity-related cancer risk.

To do this, they used data from the UK Biobank, a cross-sectional cohort of 500,000 UK residents aged 37-73 who were recruited between 2006 and 2010 and followed for a median time of 13.4 years.

Among the data collected in the database were details about the distribution of fat in their bodies and whether they developed cancer.

The researchers used Cox proportional hazards models (allowing for proportionality relationships) to identify associations between the levels and distribution of people’s body fat at the time of initial screening and their subsequent rates of cancer.

Thus, they discovered that all types of cancer, except those of the brain, cervix and testicles, are associated with obesity.

In women, the strongest links between overall fat accumulation and cancer were in gallbladder cancer, endometrial cancer, and esophageal adenocarcinoma.

In men, the strongest links between fat accumulation and cancer were for breast cancer, hepatocellular carcinoma, and renal cell carcinoma.

Regarding the accumulation and distribution of fat, differential effects were observed between the sexes in colorectal, esophageal and liver cancer.

For example, more fat stored in the abdomen was associated with oesophageal squamous cell carcinoma in women, but not in men. And vice versa: the accumulation of body fat was associated with a high risk of hepatocellular carcinoma in men, but not in women.

The study found differences in the effect of obesity on cancer risk not only between men and women, but also between postmenopausal and premenopausal women.

“Most notably, obesity is only a risk factor for breast cancer after menopause, probably due to the change in estrogen production associated with menopause.” Johansson points out.

The researchers caution that this study was largely limited to white British participants, so its conclusions might not apply to other ethnicities.

However, they plan to carry out additional studies to better understand the molecular mechanisms underlying these results and also to analyze genetic and environmental risk factors for cancer, as well as the variation in the effects of obesity before and after menopause.

Source: EFE