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Experts say healthcare professionals need to connect better with young adults. Maskot/Getty Images
  • Researchers report that cancer diagnoses continue to rise in people in the United States between 15 and 39 years old.
  • The increase is due largely to thyroid cancer, but the rates for colorectal and other cancers are also up.
  • Experts say obesity and other lifestyle issues are major factors in the increase.
  • They add that young adults often don’t seek medical care until they have been diagnosed.

Research into teen and young adult cancers has resulted in new, effective treatments for this age group over the past decade.

However, cancer diagnoses in people in the United States between 15 and 39 are still increasing, according to data from the American Cancer Society.

In a new study, researchers analyzed cancer incidence and mortality for adolescents and young adults (AYA) in the United States by age group, sex, and race/ethnicity from 2007 to 2016.

The researchers reported that multiple types of cancer, including kidney, thyroid, uterine, and colorectal, are still increasing in this age group.

Karen Knudsen, Ph.D., MBA, the chief executive officer of the American Cancer Society, told Healthline that while there has been an increase in cancer diagnoses in this age group, the mortality rate is headed downward.

The study shows that the mortality rate in the AYA population declined by 1 percent across every age group except for women aged 30 to 39 from 2008 to 2017.

“In that age group of women, there is no increase in mortality, but no decrease either,” Knudsen said.

Most recently, the incidence numbers have been driven largely by thyroid cancer, which the researchers say ascended by approximately 3 percent annually among those aged 20 to 39 years and 4 percent among those aged 15 to 19 years.

“If we take that out, it eradicates a lot of the increase,” said Knudsen.

She added that scientists are still trying to fully understand thyroid cancer, which happens when cells in the thyroid develop changes in their DNA.

But in most thyroid cancers, it’s still not clear what causes the DNA changes that cause the disease.

“There are no known underlying causes in thyroid cancer, although some subsets are inherited,” Knudsen said. “The good news is that research advances are moving forward and there are good treatments for thyroid cancer.”

Simon Davies, executive director of Teen Cancer America, which advocates for teens and young adults with cancer, notes there was a 30 percent increase in AYA cancer diagnoses from 1973 to 2015.

“We don’t know all the reasons why,” Davies told Healthline. “And that’s the reason why Teen Cancer America exists: to find answers to these questions and support this population.”

A big part of the increase in the incidence of cancer overall in young Americans, and in fact in all age groups, is obesity, Knudsen said.

She said obesity is a factor in multiple cancers, including breast, uterine, and colorectal cancer. Genetics also plays a role.

“The great takeaway from this data overall is that while incidence is still on the rise, some of these cancers can be prevented through healthy lifestyles,” Knudsen said.

Dr. Clifford Hudis, the chief executive officer of the American Society of Clinical Oncology, told Healthline that the oncology community is deeply concerned about the modifiable risk factors that could be contributing to the rise in cancer reported in AYA populations.

“We urge continued investment to help us address these challenges, improve therapy, and support better longer-term outcomes,” Hudis said.

Dr. Michael Roth, the co-director of the adolescent and young adult oncology program at M.D. Anderson Cancer Center in Texas, said that AYAs are too often simply not part of the medical system.

“Many of them have no access to healthcare after their remission and they may be in poor health,” Roth told Healthline. “We need to focus our efforts on getting them in and then keeping them healthy and in touch with providers so they are doing appropriate preventative medicine.”

Roth said teens and young adults often think they’re healthy even when they are not.

In addition, experts say younger adults often do not continue their care after they have been treated.

“Survivors of AYA cancers often do not get screening after they are cured,” Roth said. “We need to engage young adults and keep them engaged.”