An abdominal pain may be an indication that something is not right. Changes in bowel habits may also be a sign. Some people may notice blood in their stools. Doctors may chalk that symptom up to hemorrhoids, but for some people, it’s a sign of something more insidious: early-onset colorectal cancer.
Thejus Jayakrishnan treats many patients in their 30s and 40s who are establishing their careers, perhaps moving into a new home with their young children. When they find out they have colorectal cancer, they’re shocked, he says. “It’s not something you expect.” In some cases, the cancer, which takes root in the large intestine, has already spread through the body and encroached on the liver or lungs.
Though the number of colorectal cancer cases among people under 50 has been rising for decades, younger and middle-aged adults’ symptoms can still go overlooked, says Jayakrishnan, a physician at the Cleveland Clinic in Ohio. These people aren’t in the age group that doctors tend to be concerned about, he says.
That’s also been the experience of Christopher Lieu, a medical oncologist at the University of Colorado Cancer Center in Aurora. “For the last 10 years of my career, all my patients were told, ‘You’re just too young to have colorectal cancer. Don’t worry about it.’” In a June talk at the American Society of Clinical Oncology meeting in Chicago, Lieu noted that, by 2030, colorectal cancer could be the number one cause of cancer death in people ages 20 to 49. “This is a humongous issue,” he said.
The American Cancer Society has updated their guidelines in 2018 to reflect the increasing incidence of cancer. Start screening at 45, not 50.The organization now recommendsSN: 5/31/18). Yin Cao says younger people who have colorectal tumors that are early in their development may still fall through the cracks. “At least 50 percent of these cases are under age 45,” she says.
Scientists don’t know what’s driving the disease’s increase in younger adults, but they’ve been looking for answers. Recent research is starting to give some hints but the picture still remains murky.
Cao, Jayakrishnan and others are working to find ways to detect cancer earlier, before the disease has spread to other body parts. Cao’s team recently identified warning symptoms linked to the early-onset cancer. Jayakrishnan also presented a study at the ASCO June meeting, which suggested that there could be metabolic differences in people with early-onset cancers and those with average-onset.
Science News spoke with these and other doctors about what they’re learning about early-onset colorectal cancer and what questions remain. These doctors wish that more people were aware of three important aspects of this disease.
More younger adults are getting colorectal cancer, a trend that’s occurring around the world.
Cao explains that colorectal carcinoma has historically been a disease of the elderly in the United States. A landmark study in 2017 marked a significant change in the number of people diagnosed with colorectal cancer.
Scientists noted that although older people still accounted for the majority of cases, colorectal carcinoma incidence in those aged 50-64 had been trending downwards from 2000 to 2013. The rate of colorectal cancer in people aged 65 and over has dropped. However, there was a Increase of 22 percent in the number of cases among people under 50 (SN: 3/1/17). The rate of new cases increased from 59 per million young people to 72 by the end of the period.
“It’s really alarming because we saw this rising incidence in younger adults,” Cao says, and for a disease that hadn’t typically affected a younger population.
Lieu explains that the data reflected exactly what doctors observed in clinic. Looking back through the decades, scientists can track the rise’s origin to the late 1980s. Seeing the numbers creep up for a few years might have been a blip, but “what’s concerning is that [the trend] doesn’t seem to be reversing,” Lieu says. In fact, “this problem continues to get worse.” And it appears to be occurring more or less globally. Canada, Australia and United Kingdom are among the high-income nations that have seen a similar rise.
Scientists have noticed that people born in more recent generations tend to have a greater risk of developing colorectal cancer than people born in earlier generations, what’s known as a birth cohort effect. Lieu says that this means that someone who is 40 years old today faces a higher risk of colorectal carcinoma than someone born a decade earlier. The pattern, and the fact that most early-onset cases lack a hereditary link, has doctors and scientists scrambling to answer a singular question: “What are younger individuals being exposed to that could account for that risk?” he asks.
The increase in colorectal cancers that develop early may be due to a number of factors.
It’s not easy to take a magnifying glass to people’s lives and deduce what may be causing their disease. Sifting through a person’s diet history and past environmental exposures is complicated, Lieu says. “People have difficulty remembering what they ate yesterday, let alone their entire lives.”
That’s one reason the early-onset colorectal cancer picture is still so cloudy. Scientists today are looking at a wide range of possible disease drivers. These include obesity, antibiotics the gut microbiome alcohol consumption cesarean sections and a diet high in red meat and sweets.
Cao’s team, for example, has linked drinking Women who drink sugar-sweetened beverages are at an increased risk for colorectal early-onset cancer. Her group, as well as others, have reported a link between the disease People with Metabolic SyndromeThis includes conditions such as high blood pressure, excess abdominal fat and others. Western diet eatersThe other factors that affect the cost of a home include
Some teams have noted changes in the gut microbiome of people with early onset disease. They have a Different communities of gut microbesAccording to a study published in 2022, people who are diagnosed with colorectal cancer earlier may have fewer symptoms than those diagnosed at a later age. Though many scientists are exploring the microbiome’s role in early-onset colorectal cancer, so far “nothing definitive has been determined,” says Cathy Eng, a medical oncologist at the Vanderbilt-Ingram Cancer Center in Nashville.
It seems that the risk factors identified by scientists are all consistent with this. It’s also possible that younger generations are somehow more susceptible to environmental insults that kick colorectal cancer into action. “I think it’s really hard to draw a conclusion at this point,” Cao says. Lieu agrees. Scientists are still “at the hypothesis-generating stage,” he says.
Some data is even confusing. One study linked Oral antibiotics are associated with an increased colon cancer risk, but a decreased risk of rectal carcinoma.. “Even in the same study, you’re getting two very different answers,” Lieu says.
The risk factors associated with obesity and diet are not the same for everyone. In Lieu’s experience in Colorado, many of his young colorectal cancer patients are otherwise “incredibly healthy,” he says. “They’re [Division 1] athletes; they’re triathletes; they’re pretty remarkable.”
Colorectal cancer can be triggered by a combination of factors, but the exact recipe will vary from person to person. Doctors want to be able to say, “If we stop doing this one thing, then we can prevent the cancer,” Lieu says. But, he adds, “I don’t think there’s going to be a single smoking gun.”
Four ‘red flag’ symptoms may be signs of early-onset colorectal cancer.
Although scientists have yet to identify a single cause of colorectal early-onset cancer, they do have some early warning signals.
Up to two-years before diagnosis, patients with cancer may experience symptoms Abdominal pain, rectal bleed, diarrhea, and iron deficiency are all symptoms of anemia., Cao’s team reported in the Journal of the National Cancer InstituteMay is a month of celebration.
Researchers examined insurance claims from over 27,000 people, both with and those without the disease. They were looking for patterns in patients’ records — telltale symptoms documented in people under 50 who were later diagnosed with the cancer. The four signs Cao’s team identified stood out because they seemed specific to early-onset cases, and they often preceded a diagnosis by months to years. Lieu adds that unexplained loss of weight could be another symptom.
Being able to recognize the early warning signs of the disease could allow people to get ahead of the disease. A 2019 survey of more than 1,200 early onset patients and survivors found that: More than seven out of ten patients were diagnosed in an advanced stage.When their cancer had already spread to distant locations in the body or into adjacent tissues, they were diagnosed. Patients often waited several months to see their doctor. They then went to multiple doctors in order for a diagnosis.
Cao says many cases of early-onset are diagnosed at emergency rooms. “The bottom line is if someone has at least two [red flag symptoms], they really need to be aware of it,” she says. “It will definitely be worth a conversation with their primary care doctor.”
Other doctors are looking for ways to detect cancers before they spread. In a study involving 170 patients, researchers found that the The metabolic signatures of early-onset and moderate-onset disease are different.Jayakrishnan’s team reported on the findings in June to ASCO. His team observed differences in the chemical reactions between citrate and amino acid arginine among young cancer patients. If Jayakrishnan’s results hold up, such metabolic signatures could one day help doctors screen people for the disease.
“If you can detect it early,” he says, “colorectal cancer has really good treatment options. It really makes a huge difference.”
One key part of early detection may simply be wider knowledge that the early-onset disease is on the rise, says Colorado’s Lieu. Most cases of abdominal pain probably won’t be cancer, he says, but “you just don’t want to ignore it.” Raising awareness of the disease and its symptoms among both patients and doctors could “save somebody’s life.”
