Colorectal and Gastric Cancer Rates Increase in Young Adult Patient Population

Although the overall rate of colorectal and gastric cancers has gone down in the past 20 to 30 years, the rate for both cancers have risen in young adults, according to Dr. Amir Khan.

Khan, a fellow in surgical oncology at City of Hope National Medical Center in Duarte, California, was a part of a study that analyzed a large database of information regarding colorectal and gastric cancer diagnoses to determine what age group was experiencing a rise, and if there were any links to these diagnoses, such as comorbidities like smoking and diabetes.

In an interview with CURE® during the annual American Society of Clinical Oncology Gastrointestinal Cancers Symposium, Khan discussed the study results and what they mean for a younger population of patients.

CURE®: Can you discuss trends in the rate of gastric and colorectal cancer diagnoses?

Khan: Looking at the trends over the past 20 to 30 years, the overall rate of gastric and colorectal cancers has gone down in the general population. In colorectal cancer, a lot of that is due to the improved efforts in endoscopic screening and finding pre-cancerous lesions and removing them early.

The decreasing rate of gastric cancer is more because of better food storage practices and decreased smoking, but the interesting part that my project pertains to is that despite there being a decrease in the general population in both of these malignancies, there's been an increase in young adults with both gastric and colorectal cancers over the past two to three decades.

How was the database analysis conducted?

We looked at the California cancer registry, which is linked to an inpatient database within (the state). We looked at patients from 2000 to 2012 that had either a diagnosis of gastric cancer or colorectal cancer and were between the ages of 18-90. That was our basic data set to cover both malignancies and cover young adults and older adults within that population.

It's a large database study. There was close to 120,000 patients in the colorectal cancer group. There were about nearly 20,000 patients in the gastric cancer group. We did both the unit variable analysis and a multi-variable analysis to look for differences between the young patients and the older patients in terms of their demographic features, clinical features and histopathologic characteristics of their tumor.

We also looked at survival. And I think one of the most important things we did in this study was we didn't define just a vague cut off of this means early onset and cancer in young adults, and above this age is older adults. We broke our patients up into four groups based on their age.

So patients were divided at ages 18-40, 41-49, 50-64 and 65-90. Then we compared each of those three older groups to the 18-40 group individually to see how much the difference was between each group.

What did the study show?

We found that the youngest age group, 18-40, (that there were) ethnic and socio-economic disparities. Hispanic ethnicity was much more common in the younger population. In the group that was aged 65-90 maybe about 20% of gastric cancers were among Hispanics as opposed to the 18-40 group (where) 50% of patients were Hispanic.

We also found that younger patients were more likely to be uninsured and of low socio-economic status. We found that these patients may present with later stage disease — stage 3 and stage 4 — and they had certain histopathologic features that suggested a more aggressive disease process. They had more poorly differentiated tumors, (and) in terms of gastric cancer they had diffuse type pathology and poorly differentiated tumors as well.

Are there factors contributing to the rise of gastric and colorectal cancers in young adults?

At this time, it's really unclear what the mechanisms behind this rise are. There's been a lot of theories that have been thrown out in the literature. Is it because of comorbidities are increasing within the younger population, such as diabetes, smoking and obesity?

However, (when) we looked at these factors as well these comorbid conditions, we found that the younger population, 18-40 and even the 41-49 age group, actually had a much lower rate of these diseases and comorbidities like obesity, diabetes and smoking. But I think that's one of the goals that moving forward is to try and determine that. However, at this point, it is still unclear what's causing the rise in the young adult population.