A new study found that all cancer types except brain, cervical, and testicular cancers are associated with at least one obesity-related trait.

A new scientific investigation, published today in the scholarly journal Cancer Cell, sheds light on the interrelation between obesity and the heightened risk of cancer, taking into account the gender-specific aspects.

The authors, a team of scientists led by Mathias Rask-Andersen at Uppsala University, Sweden, discovered that not only the cumulative accumulation of fat but also the way fat is distributed across various body regions, affects the likelihood of cancer development in men and women differently. Moreover, this likelihood differs among different forms of cancer, such as colorectal, esophageal, and liver cancer.

In the words of Rask-Andersen, “Doctors and scientists are aware that obesity increases cancer risk, but this connection is less well known to members of the public.”

He emphasizes that these insights are crucial for evaluating risks and comprehending the intricacies of diseases connected to adiposity.

Senior author Åsa Johansson, also affiliated with Uppsala University, points out that a significant element in the analysis of diseases related to obesity is understanding the allocation of fat in various bodily segments. She explains that visceral fat, which accumulates in the abdominal region, is believed to be more detrimental compared to subcutaneous fat. Moreover, it is acknowledged that fat distribution, as well as cancer incidence rates, show discrepancies between genders, prompting a thorough, gender-specific analysis regarding adiposity and cancer risk.

This research utilized data from the UK Biobank, comprising a transverse cohort of 500,000 individuals residing in the UK, aged between 37 and 73, enrolled from 2006 to 2010, and subsequently monitored for an average duration of 13.4 years. This database encompassed information on fat distribution and subsequent cancer development among the participants.

The team employed Cox proportional hazards models to decipher the relationship between fat levels and distribution at the outset of the study and the subsequent cancer incidence rates. The results indicated that, except for brain, cervical, and testicular cancers, all other forms of cancer had an association with at least one characteristic related to obesity.

For women, the most robust associations between cancer and total fat accumulation were observed in gallbladder, endometrial, and esophageal adenocarcinoma. For men, breast cancer, hepatocellular carcinoma, and renal cell carcinoma had the strongest links with total fat accumulation. The study also revealed gender-specific variations in colorectal, esophageal, and liver cancers concerning fat distribution and accumulation.

A notable observation made by Johansson was the variation in obesity’s impact on cancer risk among men and women, as well as between post-menopausal and pre-menopausal women. She found it particularly striking that obesity acted as a risk factor for breast cancer post-menopause, likely due to alterations in estrogen production connected to menopause.

“We were surprised to see that there appeared to be a difference in the effect of obesity on cancer risk, not only between males and females, but also between post- and pre-menopausal females,” Johansson adds. “Most remarkable, obesity is only a risk factor for breast cancer after menopause, probably due to the change in estrogen production in association with menopause.” 

The authors acknowledge that the study has certain constraints, primarily being the predominance of white British participants, constituting approximately 95% of the UK Biobank. Consequently, the applicability of these findings to other ethnic groups is uncertain. Additionally, due to the age of the participants, the results may not be generalizable to younger populations.

The team is committed to conducting further research to elucidate the molecular mechanisms behind these observations. Future investigations will also concentrate on the genetic and environmental factors contributing to cancer, which vary throughout an individual’s life. This includes examining the variable effects of obesity pre and post-menopause.

Rask-Andersen emphasizes the critical nature of obesity, as it is now the most rapidly escalating risk factor for cancer globally. He advocates for initiatives to curb and mitigate obesity prevalence but stresses that weight reduction does not completely obliterate cancer risk.

“There are still many individual risk factors that play a much larger impact on specific types of cancer, such as smoking for lung cancer and exposure to the sun for skin cancer.”

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