Historically, physicians have often attributed colorectal cancer in young adults to genetic factors, particularly Lynch syndrome. However, 75% of young adults with colorectal cancer have no family history or other genetic factors. In addition, the majority of colorectal cancers due to Lynch syndrome are located in the right side of the colon, while the majority of non-hereditary, early-onset colorectal cancers are located in the left side of the colon and rectum. Therefore, although both are colorectal cancers, there are definitely differences in biological characteristics. The biology of each colorectal cancer patient is not always the same. Even though the cancers originate from the same organ, they all have their own unique genetic characteristics. To explore the complexity of colorectal cancer, some researchers are conducting retrospective genetic profiling of about 5,000 patients, mainly comparing how the genetic profiles differ between young and old people, and the results will be presented at the American Society of Clinical Oncology Gastrointestinal Oncology (ASCOGI) symposium. Others will address the epidemiological features and risk factors of early-stage colorectal cancer. Colorectal cancer in young adults is more common in inflammatory bowel disease and in people of African descent, predicting a possible association with genetic susceptibility and family history. But beyond these known risk factors, what else do we not know? The incidence of colorectal cancer has increased over the past three decades along with the increased incidence of obesity and diabetes in young adults; whether there is a causal relationship between the two is unknown but should not be ignored. Similarly, the increased consumption of sugary beverages and the decrease in milk (calcium is protective against colorectal cancer) during this period may also be a factor in the increased incidence of colorectal cancer in young people. Effective diet, nutrition, and obesity management in young adults can reduce not only the incidence of diabetes but also the incidence of colorectal cancer. Other factors that increase the incidence of colorectal cancer in older adults include physical inactivity, high protein and high calorie, high fat diets and alcohol consumption, but whether these factors contribute to colorectal cancer in young adults is unclear and data are still limited. Several other studies are exploring the changing patterns of colorectal cancer in young people in relation to gut microbes, exposure to environmental toxins, and use of statins and antibiotics over the past few decades. Early prevention and diagnosis Most of the colorectal cancers in young people are already advanced when detected, which is a challenge for treatment and long-term survival, so how to make early diagnosis? The most important point is to pay attention to it. One of the characteristics of colorectal cancer is that it is hidden, and many people have got it without knowing it in early stage. Since colorectal cancer has no symptoms or the symptoms are not obvious in early stage, it is also mistaken as chronic colitis, hemorrhoids, dysentery, adhesive bowel obstruction, intestinal polyps and ulcerative colitis. Another point is to educate young people, especially doctors, about what risk factors can lead to colorectal cancer, what are the early symptoms of colorectal cancer, to change dietary patterns and lifestyles as early as possible, and to seek early medical treatment once symptoms appear. To prevent colorectal cancer, colonoscopy should also be advocated earlier. Colorectal cancer is the best prevented cancer in the digestive system because it has a clear precancerous lesion – polyps, which can be detected by colonoscopy and most of them can be removed under colonoscopy. It is recommended that people who have a family history of colorectal cancer and have frequent symptoms such as abdominal pain, diarrhea and blood in the stool should have a colonoscopy. Colonoscopy is not as painful and scary as most people think, especially with the improvement of endoscopic equipment and examination methods, most of them can be done in a relatively easy way, and with the popularity of anesthesia endoscopy, more and more patients can do the examination in their sleep.