In a recent report out of The Lancet: Public Health, published by Dr. Ahmedin Jemal, Ph.D., and colleagues from the American Cancer Society, it was shown that millennials are twice as likely as the generations before them to develop obesity-related cancers. These cancers, such as colorectal, kidney and pancreatic cancers are increasing at an alarming rate in this population.
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The study used incidence data for invasive cancers among people aged 25–84 years diagnosed from 1995 to 2014. They looked at the incidence rate for 30 types of cancer, including 12 that are linked to obesity. Cancer diagnoses increased for 6 of 12 obesity-related cancers (multiple myeloma, colorectal, uterine corpus, gallbladder, kidney, and pancreatic cancer) in young adults, aged 25–49 years, with steeper rises in successively younger generations.
The reason(s) behind these data are yet to be elucidated, yet there are some theories and a number of questions. First off, what is the link between obesity and cancer in the first place? According to the American Cancer Society, obese individuals can have chronic low-levels of inflammation. That is, they are undergoing inflammation constantly. This chronic inflammation can go on to damage cellular DNA, which can lead to cancer. Furthermore, other obesity-related diseases could lead to cancer on their own. Another link is that obese individuals have more fat tissue and fat tissue produces excess amounts of estrogen. These high levels have been associated with increased risks of breast, endometrial, ovarian, and some other cancers.
There are several other biological theories linking obesity to cancer. But what about the link to the increase in obese-related cancers in young people? One potential mechanism could be that individuals born during the 1980s (the beginning of the millennial births) experienced potentially key developmental life stages for obesity during the beginning phases of the "obesity epidemic". Earlier and longer-lasting exposure to excess fat at such a young age could potentially increase the chances of becoming obese as they age, and then going on to developing obesity-related cancers.
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The recent report also discussed how rates for the development of obese-related cancer in young people today are similar to the rates of cancer development in older generations. More alarmingly, the report also states that this rate is climbing for younger and younger adults. In adults aged 30 years and older in the USA, excess bodyweight could account for up to 60% of all endometrial cancers, 36% of gallbladder cancers, 33% of kidney cancers, 17% of pancreatic cancers, and 11% of multiple myelomas according to another report in 2014.
The current report concluded that this increase in obesity-related cancers in young people has significant practical public health implications, especially for health-care providers and policymakers. As the millennials age, will they be more at risk for certain cancers that the older generation of today? They advise that we ramp up our efforts to screen children and adults for obesity and body-weight indexes. According to Dr. Jemel, "The future burden of these cancers could worsen as younger cohorts age, potentially halting or reversing the progress achieved in reducing cancer mortality over the past several decades".
Sources: The Lancet: Public Health, www.cancer.org, International Journal of Obesity and Metabolic Disorders, CA A Cancer Journal For Clinicians, Forbes.com