Rectal cancer is not rare. It accounts for roughly 25% to 30% of all large bowel cancers, making it one of the more common cancer types worldwide. In the United States, colorectal cancer as a whole occurs at a rate of 37.1 new cases per 100,000 people each year, and rectal cancer represents a substantial share of that number. By any standard medical definition, this is a common disease.
How “Rare” Is Defined in Medicine
The U.S. Food and Drug Administration defines a rare disease as one that affects fewer than 200,000 people in the country. Rectal cancer far exceeds that threshold. With tens of thousands of new cases diagnosed each year in the U.S. alone, it doesn’t come close to qualifying. For context, colorectal cancer is the third most commonly diagnosed cancer in both men and women, and rectal cancer makes up nearly a third of those cases.
Rectal Cancer vs. Colon Cancer
The terms “colon cancer” and “rectal cancer” are often grouped together as “colorectal cancer,” but they are increasingly recognized as distinct diseases. The rectum is defined as the last 16 centimeters of the large bowel before the anus. Tumors in this segment behave differently, require different surgical approaches, and respond differently to treatment than tumors higher up in the colon.
In a large analysis of over 370,000 patients, about 70% had colon cancer and 30% had rectal cancer. So while rectal cancer is less common than colon cancer, it’s far from unusual. Researchers have argued that the two should be studied and classified separately because they differ in molecular biology, risk factors, and how they’re treated. For example, physical activity appears to help prevent colon cancer but doesn’t show the same protective effect for rectal cancer.
Who Gets Rectal Cancer
Men are diagnosed at higher rates than women. In the U.S., the age-adjusted incidence rate for colorectal cancer is 41.4 per 100,000 for men compared to 32.5 per 100,000 for women. This pattern holds globally: in Europe, which has the highest regional incidence, men develop colorectal cancer at a rate of 37.9 per 100,000 versus 24.6 per 100,000 for women.
Geography plays a significant role. Hungary, Slovakia, and Norway have the highest colorectal cancer rates in the world, exceeding 41 per 100,000 people. Countries in sub-Saharan Africa have the lowest, with Guinea at just 3.3 per 100,000. These differences likely reflect a mix of diet, screening access, lifestyle factors, and genetics. Broadly, rates are highest in Europe and Oceania, moderate in North America and Asia, and lowest in Africa.
Rising Rates in Younger Adults
One of the most concerning trends in cancer epidemiology is the increase in colorectal cancer among people under 50. A global analysis published in The Lancet Oncology found that early-onset colorectal cancer rates climbed in 27 countries over the most recent decade. New Zealand, Chile, Puerto Rico, and England saw the steepest increases, with annual rises of roughly 3.5% to 4% per year. In 23 other countries, rates remained stable, but nowhere were they declining significantly in this age group.
The reasons are still being investigated, but the trend has already changed screening recommendations. The U.S. Preventive Services Task Force now recommends that average-risk adults begin screening at age 45, down from the previous threshold of 50. Screening continues through age 75 at regular intervals, using colonoscopy or other approved methods.
What This Means for You
If you searched this question because you or someone you know was diagnosed, the diagnosis is unfortunately not unusual. Rectal cancer is well-studied, with established treatment pathways and a large body of clinical experience to draw from. The fact that it’s common also means there are extensive support networks, clinical trials, and specialist centers focused on it.
If you searched because you’re wondering about your own risk, the most actionable step is screening. Catching precancerous growths early, before they develop into cancer, is the single most effective way to reduce your risk. Starting at 45 for average-risk individuals, or earlier if you have a family history or other risk factors, gives you the best chance of prevention or early detection when outcomes are most favorable.