A growing body of literature indicates that the incidence of colorectal cancer is rising among people under age 50, according to Jason A. Zell, DO, MPH. Dr. Zell is the corresponding author of one of the two recent studies finding significant increases in colorectal cancer among adults aged 20 to 49.1,2 Writing in the Journal of Adolescent and Young Adult Oncology, Dr. Zell and colleagues from the University of California (UC), Irvine, noted the study also found that colorectal cancer in young adults “was more likely to be diagnosed at an advanced stage and therefore less likely to be cured.” The investigators suggested, “greater focus on early detection among young, symptomatic individuals may be warranted.”1
Among the several possible explanations proposed “for the concerning increase in colorectal cancer incidence among adults younger than 50” is a “low index of suspicion from physicians.” Asked by The ASCO Post if this study should serve to raise that index of suspicion, Dr. Zell replied, “I certainly hope so. But not just this study. There have been numerous reports showing that colon cancer is rising in those under 50. Our study shows a little more granularity, even looking at the very young, age 20 to 29, but overall I think there is enough literature out there to help inform the public and also primary care physicians that this is a problem.” Dr. Zell is Assistant Professor, Department of Medicine and Department of Epidemiology, and Program Director, Hematology/Oncology Fellowship Program, Division of Hematology/Oncology at the UC Irvine Medical Center.
A recent article in JAMA Surgery2—“which shows very similar findings—[and] our article essentially were published at the same time and are spawning a lot of interest right now,” Dr. Zell noted. Both studies found that the significant increase in colorectal cancer in young adults occurred amid a decline in colorectal cancer incidence among people older than 50. This decline has been attributed to colorectal cancer screening and removal of polyps among the over-50 age group. While both studies recognize the importance of early detection and avoiding treatment delays, neither concludes that colorectal cancer screening should be generally extended to people under 50.
‘Considered on the Differential Diagnosis’
A Health Day article about the increasing incidence of colorectal cancer among younger adults quoted Dr. Zell as saying, “We need more awareness of the trend among patients and doctors. Because at this point, key symptoms among young adults, like blood in the stool, weight loss, or other complaints, are often ignored.”3
Dr. Zell expanded on this comment during an interview with The ASCO Post: “Patients come in with symptoms, and it is important for physicians not to ignore those symptoms in patients who are young, simply because they are young. This is a message that we can promote without being very controversial at all: Colon cancer is rising in the young. The risk is still low, but if a young patient presents with bleeding, pain, or some of these other symptoms you would associate with colon cancer, it should be considered in the differential diagnosis.”
Identifying High-Risk Groups
Data from the California Cancer Registry were used to examine colorectal cancer incidence with a focus on young adults in order to identify high-risk subgroups, the investigators explained. “We assessed age-specific incidence rates by race/ethnicity, gender, and colorectal tumor location and calculated the biannual percent change to monitor change in incidence over the 22-year study period.” The study population from the California Cancer Registry was 71% white, 12% Hispanic, 10% Asian/Pacific Islander, and 7% African American.
The study found that the absolute incidence of colorectal cancer was far lower for young adults than for adults aged 50 and over. Among the 231,544 incident colorectal cancer cases, just 5,617 were among young adults. Rates ranged from 0.7 per 100,000 among Hispanic and African American females aged 20 to 29 up to 5.0 per 100,000 among Asian/Pacific Islander males aged 30 to 39. Those rates increased over time. Regional disease was the most common stage for all race/ethnicity and age groups, but young adults had a greater proportion of colorectal cancer diagnosed at a distant stage compared with any other age group.
Unexpected Findings
The biannual percent change in colorectal cancer significantly decreased among people 50 years and older, but the biannual percent change significantly increased among pre–screening age adults aged 20 to 29, 30 to 39, and 40 to 49, the researchers reported. “Although we found Hispanics to have the lowest overall rates of [colorectal cancer], this group also had the largest increase in incidence over the 1988–2009 study period,” the researchers wrote. “Of note, the greatest observed biannual percentage changes were for distal colon cancer among Hispanic females aged 20 to 29 [biannual percent change = +15.9%, P = .042] and Hispanic males aged 30 to 39 [biannual percent change = +10.4%, P < .001].”
These “dramatic increases in the young Hispanics were unexpected findings,” Dr. Zell said. “We think it is important to analyze our data by race and ethnicity for a number of reasons. Historically, it is known that African Americans are at a higher risk of colon cancer, which is why several societies actually recommend lower screening ages for that population. But Hispanics have been essentially ignored by those types of recommendations.”
The American College of Gastroenterology and the Colon Cancer Alliance recommend screening for colorectal cancer start at age 45 for African Americans. The recommendations from the Colon Cancer Alliance, a national patient advocacy group that Dr. Zell works with, also state: “People with a personal or family history of colon cancer, inflammatory bowel disease, or who are experiencing symptoms are considered ‘high risk’ and should begin screening before age 50.”
The marked increases in colorectal cancer among young Hispanics need to be confirmed by additional studies, Dr. Zell added. “But the data are real. The state of California cancer registry database contains the highest quality reporting standards. So I do believe this is a true effect that is happening in California.”
The finding highlights the value of doing this kind of research, Dr. Zell noted. “Occasionally you will find things that are new and unsuspected, which need to be confirmed. But it is also showing us that what we know in older adults is not necessarily the same for younger adults.”
Predisposing Risk Factors
Another possible reason cited for the increase in colorectal cancer among adults younger than 50 was a “a higher prevalence of predisposing risk factors that allow for accelerated tumorigenesis in younger patients.” These risk factors include a family history of hereditary colorectal cancer syndromes such as familial adenomatous polyposis and hereditary nonpolyposis colorectal cancer.
“The greatest limitation of our study is that we cannot address how many of these people have either hereditary colon cancer syndrome, which we would expect to occur in up to 5% of patients, but also a simple family history of colon cancer in a first-degree relative, known as familial colon cancer,” the investigators noted. “We cannot determine from our data set who has familial colon cancer and who doesn’t.”
Even if family history was known, that wouldn’t be enough to adequately assess colorectal cancer risk among adults younger than 50. A previous study found that among 180 patients younger than 50 diagnosed with colorectal cancer, only 8% had a first-degree family member with colorectal cancer,4 “which clearly demonstrates that using family history alone is inadequate in prognosticating risk among the [young adult] and unscreened population,” Dr. Zell and his coauthors wrote.
Access to Care and Health Insurance
“So 92% would go undetected if we solely relied on family history,” Dr. Zell told The ASCO Post. “We need to look at other things.” In addition to the patient’s symptoms, they include access to care and insurance coverage. Colon cancer patients under age 50 are more likely to be underinsured, an important factor that “relates to our study in two ways,” Dr. Zell noted.
“First, we found that young patients with colorectal cancer had higher-stage disease at diagnosis. That is the number 1 predictor of survival outcome—stage at diagnosis. It is expected in an unscreened population that you would find colon cancer at a more advanced stage, but it is also very concerning because colon cancer is a curable disease when detected early. So the lack of insurance could easily explain the higher stage at diagnosis,” he said.
“The other thing that it hints at is that patients without insurance are very unlikely to have early detection,” he continued. “If you don’t have access to care and you rely on an emergency room, for example, even if you do have signs of colon cancer, it is unlikely to be detected at an early stage.”
As more information about the rising incidence of colon cancer is published and reported in the news, raising awareness among primary care physicians and their patients, Dr. Zell expected more cases of colorectal cancer among people under 50 would be detected early. In addition, “as access to care increases, it will be easier to effectively do early detection,” Dr. Zell said. The study looked at colorectal cancer incidence from 1988 through 2009, so the impact of the Affordable Care Act would not be reflected. “But certainly 5 years from now, we might start seeing the very beginning of those changes,” Dr. Zell noted.
Requires Further Investigation
The role of diet among younger patients who develop colorectal cancer is “an important area of investigation that requires further study. Diet “also may inform some of the differences by race ethnicity, because we know diet is related to cultural background and race/ethnicity,” Dr. Zell stated. “We know that processed meats, red meats, are associated with colon cancer incidence, but interestingly, they are also associated with poor outcomes among survivors.”
The study concludes, “More research is needed to characterize individuals with young-onset [colorectal cancer] and to determine how these individuals differ from young people who do not develop [colorectal cancer].”
Now that large population-based studies have been completed, Dr. Zell suggested that it is time to focus on cohort studies, “not just looking at patients we already know have young onset colon cancer, particularly those without Lynch syndrome or [familial adenomatous polyposis], because there is already a lot of interest and research in that area—but broadening the focus to include both familial and sporadic colorectal cancer. I think that would be really important.” ■
Disclosure: Dr. Zell reported no potential conflicts of interest.
References
1. Singh KE, Taylor TH, Pan CG, et al: Colorectal cancer incidence among young adults in California. J Adolesc Young Adult Oncol 3:176-184, 2014.
2. Bailey CE, Hu C-Y, You YN, et al: Increasing disparities in the age-related incidences of colon and rectal cancers in the United States, 1975-2010. JAMA Surgery 150:17-22, 2015.
3. Mozes A: Colon cancer rates rising among Americans under 50. Health Day, January 30, 2015.
4. Myers EA, Feingold DL, Forde KA, et al: Colorectal cancer in patients under 50 years of age: A retrospective analysis of two institutions’ experience. World J Gastroenterol 19:5651-5657, 2013.
