Most of these cancers have traditionally shown up in patients later in life, usually in their 60s and 70s.
The new study may serve as a warning that if the obesity epidemic continues, there could be an explosion of these fat-sensitive cancers in the years to come, said the study's senior author, Dr. Ahmedin Jemal, scientific vice president of surveillance and health services research at the American Cancer Society. These signals may tell cells to divide more quickly, which can put people at risk of cancer.
Younger groups also saw higher increases in the rise of incidence in womb cancer, gallbladder disease and multiple myloma, compared with older groups.
The younger the age group, the greater the size of the increase in all seven of the cancer types except for thyroid cancer.
It's not possible to definitively attribute the recent cancer increases to obesity - but the new report notes that the upticks in cancer for young people coincided with a doubling in rates of childhood and adolescent obesity between 1980 and 2014, making weight a likely contributor.
However, Chang warns against overgeneralizing on the basis of an epidemiological study.More news: Melbourne Cup winning trainer faces ban
In a sweeping study covering two-thirds of the USA population, they showed that half a dozen cancers for which obesity is a known risk factor became more frequent from 1995 to 2015 among women and men under 50. "How much each of those factors contribute to cancer is less clear". But they said the trends showed the alarming impact of the obesity epidemic.
Millennials are on their way to being one of the heaviest generations on record. Research in the United Kingdom shows at least seven in 10 people born between the early 1980s and mid-1990s will likely be overweight or obese by their mid-30s and 40s. Only five in 10 baby boomers were obese at that same age. People in the 40 to 44 age bracket only experienced a 0.72 percent increase, according to the study.
A study in the New England Journal of Medicine past year found nearly 60% of the nation's children and teens will be obese by the age of 35 if the trend continues, with around half of the projected weight gain occurring during childhood.
That upward trajectory has experts concerned about associated medical conditions such as heart disease, diabetes and up to 13 types of cancer.
Researchers from the American Cancer Society studied cancer data covering half of the United States population between 1995 and 2014.
Obesity is also often associated with an unhealthy lifestyle - eating junk food and not getting enough fruit, vegetables or exercise - factors which are separate but linked and also known to increase the risk of cancer.
According to the charity Cancer Research UK, obesity is the second biggest preventable cause of cancer in the UK, after smoking.More news: Naomi Campbell, boyfriend Liam Payne attend Davido’s London concert
"We know in animal models that obesity accelerates the onset of cancer", said Berger.
Two pancreatic cancer cases, for example, were diagnosed among every 100,000 24 to 49-year-olds from 2010 to 2014, compared with 37 cases for every 100,000 people aged 50 to 84.
Excess weight may promote cancer in several ways.
In contrast, of the 18 additional, most common cancers analyzed, the incidence of only two - gastric non-cardia cancer and leukemia - increased among young adults in the same time period.
Obese people will not definitely develop cancer but they are at a higher risk than people who are a healthy weight.
Chang agreed that urgent action is needed. "Those things should be the number one priority of any public health policy".More news: Donald Trump says Nancy Pelosi was 'very rigid' during shutdown