Stomach cancer cases increasing among younger Americans as study finds it spreads slower in older patients
While stomach cancers are typically diagnosed in patients in their 70s, people in their 30s, 40s and 50s are more at risk than they used to be in the US, say Mayo Clinic researchers.
This early-onset cancer now makes up more than 30% of stomach cancer diagnoses. The team also found that many people under 60 who develop stomach cancer — also known as gastric cancer — have a "genetically and clinically distinct" disease.
According to researchers, compared to stomach cancer in older adults, this new, early-onset form often grows and spreads more quickly, has a worse prognosis, and is more resistant to traditional chemotherapy treatments.
Traditional risk factors for developing stomach cancer among older Americans, such as smoking tobacco or binge drinking, did not appear to correlate with its early-onset counterpart.
"I think this is an alarming trend, as stomach cancer is a devastating disease. There is little awareness in the US of the signs and symptoms of stomach cancer, and many younger patients may be diagnosed late — when treatment is less effective," says senior author Dr. Travis Grotz, a Mayo Clinic surgical oncologist, in the analysis.
Stomach cancer is the 16th most common cancer in the US, according to the American Cancer Society. There were an estimated 27,510 new stomach cancer cases in the US and 11,140 deaths in 2019. Stomach cancer has a five-year survival rate of 31.5%, according to the National Cancer Institute.
According to the World Health Organization (WHO), cancer is a leading cause of death worldwide, accounting for an estimated 9.6 million deaths in 2018. Stomach cancer was the third most common cause of cancer death in 2018.
For their research, the team studied 75,225 cases using several cancer databases to review stomach cancer statistics from 1973 to 2015. While the average age of someone diagnosed with stomach cancer is 68 currently, they found that people in their 30s, 40s and 50s are more at risk now.
There is no clear cutoff age for the definition of early-onset and late-onset stomach cancer, but researchers found the "distinctions held" whether they used an age cutoff of 60, 50 or 40 years.
The proportion of early-onset gastric cancer has doubled from 18% of all cases in 1995 to now more than 30% of all gastric cancer cases, says the team.
The analysis shows that the incidence of early-onset disease decreased by 1.9% annually from 1973 to 1995 and then increased by 1.5% through 2013. By contrast, late-onset stomach cancer decreased by 1.8% annually during the study period.
Researchers found that besides being more deadly, early-onset stomach cancer is also genetically and molecularly distinct.
"We know from prior studies that traditional gastric cancer has declined dramatically in incidence in the US during the past several decades," says the study published in Surgery.
"However, our data demonstrate that early-onset gastric cancer is not associated with traditional risk factors and has been steadily increasing as a proportion of all gastric cancer cases for nearly three decades, now comprising more than 30% of all new gastric cancer cases as of 2015," continues the study.
"We have shown that the risk factors of smoking and binge drinking are only associated with later-onset gastric cancer, and not early-onset gastric cancer," it adds.
Dr. Grotz explains that the increased rate of the early onset disease is not from earlier detection or screening. "There is no universal screening for stomach cancer, and the younger patients actually presented with later-stage disease than the older patients,” says Dr. Grotz in the analysis.
"Hopefully, studies like this will raise awareness and increase physician suspicion of stomach cancer, particularly in younger patients. Younger patients who feel full before finishing a meal, or have reflux, abdominal pain, unintentional weight loss and difficulty eating should see their health care provider," says Dr. Grotz.
Using large databases of medical records such as the Rochester Epidemiology Project, the research team plans to better identify risk factors for early-onset stomach cancer.
"Additional investigation is necessary to identify risk factors for early-onset gastric cancer to inform public health policy on risk reduction strategies," says the team.