The incidence of gastric cancer among younger adults (20–59 years of age) in the United States has been increasing steadily since the 1990s. Such cases now make up at least 30% of all new gastric cancer diagnoses, a new analysis reveals.
"I think this is an alarming trend, as stomach cancer is a devastating disease, so hopefully studies like this will raise awareness and increase physicians' suspicion of stomach cancer, particularly in younger patients," senior author Travis Grotz, MD, Mayo Clinic, Rochester, Minnesota, commented in a statement.
"Typically, we see stomach cancer being diagnosed in patients in their 70s, but increasingly, we are seeing 30- to 50-year-old patients being diagnosed [with the disease]," he added.
Early-onset gastric cancer (EOGC) is genetically and clinically distinct from what has traditionally been seen in older adults (>60 years), which is referred to as later-onset gastric cancer (LOGC).
It also has multiple features that are associated with a worse prognosis, the same analysis shows.
The study was published in October 2019 in the journal Surgery.
"We know from prior studies that traditional gastric cancer has declined dramatically in incidence in the United States during the past several decades, owing in large part to risk-factor reduction, including smoking cessation, improvements in medical management of acid reflux, and increased treatment of H pylori," the authors observe.
"However, our data demonstrate that EOGC is not associated with traditional risk factors and has been steadily increasing as a proportion of all [gastric cancer] cases for nearly 3 decades," they add.
"Additional investigation is necessary to identify risk factors for EOGC to inform public health policy on risk reduction strategies," they suggest.
Symptoms of EOGC include feeling full before finishing a meal or having difficulty eating; acid reflux or abdominal pain; and unintentional weight loss, they add.
The authors suggest that novel treatment approaches are needed for patients with EOGC, because current strategies are not very effective for these patients.
Details of the Findings
For this analysis, the research team evaluated incident cases of gastric cancer reported to the Surveillance, Epidemiology and End Results (SEER) registry from 1973 to 2015. The researchers compared reports for patients aged 20 – 59 years and those aged ≥60 years.
A total of 75,225 cases of gastric cancer were identified across the study, including 18,608 diagnoses of EOGC and 56,617 diagnoses of LOGC.
Analysis showed that the incidence of EOGC declined by 1.9% per year from 1973 to 1995, then increased by 1.5% a year from 1995 to 2013 (P < .05).
In contrast, the incidence of LOGC steadily declined by 1.8% per year (P < .05) during the entire study period (1973 – 2015), the researchers note.
"As a percentage of all gastric cancer cases, the proportion of EOGC cases has increased rapidly from a nadir of 18.4% in 1990 to >30.0% in every year since 2012 (P < .05)," the investigators report.
This trend was seen in all ethnic groups, they note.
Results from a sensitivity analysis showed that, when using age 40 years to define EOGC, the incidence increased from a low of 1.7% in 1973 to 3.5% in 2015 — effectively doubling the incidence of gastric cancer during the study interval.
The same results were seen when the investigators used the age of 50 as a cutoff definition for EOGC. In that analysis, the incidence initially decreased until 1982, then effectively doubled from its nadir by 2015.
"EOGC patients were more often male...nonwhite...with proximally located tumors," the researchers observe.
Different Type of Tumors
The team emphasizes that the gastric tumors seen in younger patients are different from those seen in older patients.
Patients with EOGC were more likely to have certain tumor characteristics, including tumors with poorly differentiated histologic grade, signet-ring cells, Lauren-diffuse histologic type, and regional or distant metastasis at presentation.
Table. Differences Between EOGC Tumors and LOGC Tumors
| Poorly Differentiated Histologic Grade | Signet-Ring Cells | Lauren-Diffuse Histologic Type | Regional/Distant Metastasis at Presentation | |
|---|---|---|---|---|
| EOGC | 55.2% | 19% | 25.7% | 49.5% |
| LOGC | 46.9% | 10.4% | 15% | 40.9% |
The team investigated potential underlying genetic differences between EOGC and LOGC using the Cancer Genome Atlas (TCGA), a publicly available dataset that catalogs genome alternations in many types of tumors.
Among those patients for whom both clinical and genomic data were available from TGCA, the researchers found that EOGC cases were more likely to be an Epstein-Barr virus or a genomically stable subtype.
In contrast, LOGC cases were more likely to be a microsatellite instability subtype (all P < .01).
Behavioral Gastric Cancer Risk Factors
The research team also evaluated data from the Behavioral and Risk Factor Surveillance Survey (BRFSS) to identify common risk factors for EOGC and LOGC.
Self-reported risk factors from the BRFSS indicated that smoking and binge drinking correlated with the risk for gastric cancer in the LOGC cohort but not the EOGC cohort.
That said, strong risk factors for gastric cancer, such as H pylori infection and the consumption of nitrites and smoked foods, were not included in the BRFSS risk assessment survey, so these factors could not be assessed in the cohort overall, the team notes.
The authors have disclosed no relevant financial relationships.
Surgery. 2019;166:547-555. Abstract
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Cite this: 'Alarming Trend': Gastric Cancer Increase in Younger Adults - Medscape - Dec 30, 2019.
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