Obesity-Linked Factors Drive Rising Cancer Rates Across Age Groups

Cancer incidence rates have increased for several cancer types, specifically among younger and older adults with obesity, according to findings conducted by researchers from The Institute of Cancer Research and Imperial College London.

The study authors, who published their findings in Annals of Internal Medicine, noted the results can aid guidance for future research priorities and public health guidelines.^1,2

“Over the past several decades, there has been an insidious increase in the incidence of cancer in young adults. Furthermore, young adults appear to be at risk for presenting with more advanced stages of disease and more aggressive histologic characteristics than older patients,” the authors said in the study. “Although this has rightly attracted the attention of the media, advocates, and researchers, older adults continue to account for most new cancer cases and deaths worldwide.”³

How Can Overweight and Obesity Lead to Cancer?

Individuals who are overweight or obese face an increased risk of getting cancer, emphasizing the need to keep a healthy weight to lower risk, according to the CDC. This increased risk includes 13 types of cancer, which make up nearly 40% of all cancer diagnosed annually in the US, involving adenocarcinoma of the esophagus; breast in women who have gone through menopause; colon and rectum; uterus; gallbladder; upper stomach; kidneys; liver; ovaries; pancreas; thyroid; meningioma; and multiple myeloma.⁴

Being overweight or obese can cause chronic inflammation and elevated levels of insulin, insulin-like growth factor, and sex hormones, which may contribute to cancer development. The likelihood of developing cancer increases with both the amount of excess weight and the duration of being overweight.⁴

According to CDC data, over 716,000 new obesity-associated cancers occurred in the US in 2022, with more than 220,000 cases among men and 495,000 among women. In women, postmenopausal breast cancer is the most common obesity-associated cancer, while colorectal cancer is most common among men. Over 90% of these cancers occurred in individuals aged 50 or older. The investigators noted the data demonstrated types linked to obesity but did not estimate how many cases were directly caused by obesity.⁴

Trends in Cancer Incidence Among Younger and Older Adults

With the rise of cancer incidence in younger and older adults over the past several decades, researchers conducted a surveillance study to assess trends in previous cancer types that reported an incidence increase among younger and older adults. The study included younger adults aged 20 to 49 years and older adults aged 50 years and older from 42 countries in Asia, Europe, Africa, North and South America, and Australasia with annual cancer incidence data from 2003 to 2017.^1,2

The researchers used joinpoint regression to calculate the average annual percentage change in incidence rates among various cancers, including leukemia, colorectal, stomach, breast, prostate, endometrial, gallbladder, kidney, liver, esophageal, oral, pancreatic, and thyroid cancer.^1,2

The results demonstrated that incidence rates in younger adults increased in over 75% of the countries between 2003 and 2017 for thyroid cancer, breast cancer, colorectal cancer, kidney cancer, endometrial cancer, and leukemia. Further results revealed incidence rates of these cancer types also increased in older adults, excluding colorectal cancer, which only rose in half the country. Regarding liver, oral, esophageal, and stomach cancers, the researchers noticed a decrease in younger adults in over half the countries.^1,2

The findings suggest that rising cancer incidence rates are likely driven by shared risk factors across all age groups rather than factors unique to younger adults. Most cancers that increased in both younger and older adults were linked to obesity, with endometrial and kidney cancers showing the strongest connection.^1,2

How Can Pharmacists Help Prevent or Treat Obesity and Cancer Risk?

Pharmacists can aid prevention and combat obesity-related cancer by helping patients reach a healthy weight. Explaining that keeping a healthy weight can lower an individual’s cancer risk and connecting patients with community services that provide guidance on healthy food options and activity could be beneficial. If an individual with a higher body mass index needs additional support with weight loss, pharmacists can discuss the use of medications, surgery, and other treatments. Following a cancer diagnosis, pharmacists can support patients during treatment and provide knowledge to lessen the burden when receiving care.³

REFERENCES

1. Amy Berrington de Gonzalez, Martina Brayley, Reuben Frost, et al. Trends in Cancer Incidence in Younger and Older Adults: An International Comparative Analysis. Ann Intern Med. [Epub 21 October 2025]. doi:10.7326/ANNALS-24-02718

2. Obesity-related cancer rising among both younger and older adults worldwide. News release. EurekAlert! October 20, 2025. Accessed October 28, 2025. https://www.eurekalert.org/news-releases/1101822

3. Christopher Cann, Efrat Dotan. Generations at Risk: Unveiling the Global Increase in Cancer at Both Ends of Adulthood. Ann Intern Med. [Epub 21 October 2025]. doi:10.7326/ANNALS-25-03883

4. CDC. Obesity and Cancer. News release. Updated June 11, 2025. Accessed October 28, 2025. https://www.cdc.gov/cancer/risk-factors/obesity.html