Young Adults With CRC and Gastric Cancer Have Worse Survival, Clinical Features

Amir Ali Khan, MD

Despite a decrease in gastric cancer and colorectal cancer (CRC) diagnoses in the overall population, there has been an “alarming” rise in the incidence of these malignancies in young adults, explained Amir Ali Khan, MD.

In a large retrospective database analysis presented at the 2020 Gastrointestinal Cancers Symposium, investigators looked at the demographic, clinical, and histopathologic features, as well as survival outcomes, in patients with gastric cancer or CRC. Nearly 117,500 patients with CRC and 20,000 patients with gastric cancer were included in the trial and were stratified into 4 age groups: 18 to 40 years, 41 to 49 years, 50 to 64 years, and 65 to 90 years.

Of note, the trial showed that Hispanic ethnicity was more common in young adults aged 18 to 40 compared with older patients aged 41 to 90 with both gastric cancer and CRC.

Additionally, young adults had distinctly worse clinical and histopathologic features compared with older patients. A higher incidence of poorly differentiated tumors, signet ring features, and synchronous peritoneal metastases, as well as higher-grade disease at presentation, were seen in younger patients versus older patients across both tumor types.

Moreover, young adults with gastric cancer or CRC had a greater 5-year survival than older patients. However, results of a subgroup analysis revealed that young adult patients with stage I gastric cancer had a lower 5-year survival rate at 65.1% (95% CI, 49.7%-76.9%) compared with adults aged 41 to 49 years at 70.7% (95% CI, 62.5%-77.3%), and adults aged 50 to 64 years at 69.1% (65.2%-72.7%).

In an interview with OncLive, Khan, a general surgery specialist at City of Hope, discussed the results of the database analysis and the remaining questions with young adult patients with CRC and gastric cancer.

OncLive: What trends have emerged in gastric cancer and CRC diagnoses over the past few decades?

Khan: Over the last 20 to 30 years, the overall rates of gastric cancer and CRC have gone down in the general population. In CRC, that is largely due to the improved efforts in endoscopic screening, [which allows us] to remove precancerous lesions early. In gastric cancer, it is more because of better food storage practices and decreased smoking.

Despite there being a decrease in the general population for these malignancies, there has been an increase in young adults [who develop] gastric cancer or CRC over the past 3 decades.

What was the methodology for this database analysis?

We looked at the California Cancer Registry, which is linked to an inpatient database within California. We looked at patients from 2000 to 2012 who had either a diagnosis of gastric cancer or CRC and were between the ages of 18 and 90. Our basic dataset covered younger and older adults in both malignancies.

It is a large database study. There were close to 120,000 patients in the CRC group and nearly 20,000 patients in the gastric cancer group. We did a univariate analysis and a multivariate analysis to look for differences between the younger and older patients in terms of demographic features, clinical features, and histopathologic characteristics of their tumors. We also looked at survival outcomes.

Importantly, we did not define a vague cutoff for early onset cancer in young adults and older adults. Instead, we broke our patients into 4 groups based on age. Patients were divided at ages 18 to 40, 41 to 49, 50 to 64, and 65 to 90. We compared the 3 older groups to the youngest group to see any differences.

What were the results of the analysis?

The youngest age group had a high ethnic and socioeconomic disparity. The Hispanic ethnicity was more common in the younger population. In the age 65 to 90 group, about 205 of the gastric cancers were among Hispanics. In the age 18 to 40 group, 50% of patients were Hispanic.

Additionally, we found that the younger patients were more likely to be uninsured and of low socioeconomic status. They may present with stage III or stage IV disease.

Finally, younger patients had certain histopathologic features that suggested a more aggressive disease process. They had more poorly differentiated tumors and a diffuse-type pathology.

What factors may have contributed to the increased rate of gastric and CRC among a younger population?

At this time, the mechanisms behind this rise are unclear. There have been a lot of theories [posed] in the literature. Is it because of comorbidities, such as diabetes, obesity, and smoking are increasing within the younger population?

We looked at these comorbid conditions [in our analysis] and found that the younger populations, including the age 18 to 40 group and 41 to 49 group, had a lower incidence of these diseases. One goal moving forward is to determine what is causing this rise [of gastric cancer and CRC] in the young adult population.

What are the next steps of this research?

We are working toward writing the manuscript and publishing this paper. Moving forward, [we want] to look at the genomic profiles of these patients to study the molecular characteristics [of their disease]. Additionally, [we want] to look at the actual tumor specimens to see what genetic factors are common between patients with either gastric cancer or CRC. Perhaps there is some molecular basis that is driving this disease process in young adults.

Khan AA, Ituarte PHG, Paz IB, et al. The alarming rise in gastric and colorectal cancers in young adult patients: analysis of large databases. J Clin Oncol. 2020;38(suppl; abstr 805). doi: 10.1200/JCO.2020.38.4_suppl.805.