Colorectal cancer, which includes both colon and rectal cancers, is the third most common cancer worldwide. This disease begins when abnormal growths, called polyps, form in the lining of the large intestine, often taking many years to develop into cancer. The lifetime risk for an average person is about one in twenty-five, but a family history of the disease can substantially change that outlook. Understanding the specifics of your family history is the initial step toward creating a clear, actionable plan for prevention and early detection and managing your personal risk.
Understanding Familial Colon Cancer Risk
A diagnosis in a family member, even a grandparent, does elevate your risk above the general population level, making your history relevant to a physician. The degree of increased risk depends primarily on the affected relative’s distance from you and their age at diagnosis. First-degree relatives include parents, siblings, and children, while second-degree relatives include grandparents, aunts, and uncles. A grandfather’s diagnosis means you have a second-degree relative with the disease.
While the highest risk increase is associated with a first-degree relative, especially one diagnosed before age 50, a second-degree relative’s diagnosis is still relevant. For example, studies suggest that individuals whose second-degree relative had early-onset cancer (before age 50) are approximately three times more likely to develop early-onset colorectal cancer. The seriousness of your family history increases if there are multiple affected relatives across different generations or if any were diagnosed at a young age.
Gather details including the exact age your grandfather was diagnosed, the location of the tumor, and if there are any other affected relatives on either side of your family. This information allows a healthcare provider to accurately calculate your risk level. In a small percentage of cases, a strong family history may suggest a hereditary cancer syndrome, such as Lynch Syndrome, which requires specialized genetic counseling and an accelerated screening schedule.
Adjusted Screening Schedules Based on Family History
For individuals whose family history places them at a higher risk, medical guidelines recommend starting screening earlier than the standard age of 45 for the general population. The most common rule is to begin a colonoscopy either at age 40 or ten years before the age of the youngest affected first-degree relative, whichever comes first. Although your grandfather is a second-degree relative, discuss your family history with a doctor to determine if the pattern of cancer warrants this accelerated schedule. You may qualify for earlier screening if you have a first-degree relative diagnosed before age 60, or if you have two or more first-degree relatives diagnosed at any age.
A colonoscopy is the preferred method for high-risk individuals because it is both diagnostic and therapeutic. During the procedure, the physician can directly visualize the entire colon and remove any precancerous polyps before they develop into cancer. If your initial colonoscopy is clear, the recommended interval for repeat screening is typically every five years, which is shorter than the ten-year interval suggested for those at average risk.
Alternative screening methods exist, such as the Fecal Immunochemical Test (FIT), which looks for blood in the stool, and various stool DNA tests that detect genetic changes. While these are options for average-risk individuals, they do not allow for the removal of polyps at the time of the test, nor do they provide the same level of direct visual inspection as a colonoscopy. Consulting with a primary care physician or a gastroenterologist is necessary to establish a personalized, evidence-based screening timeline that accounts for your family history.
Proactive Lifestyle Measures for Risk Reduction
Alongside timely medical screening, there are several lifestyle changes you can implement to reduce your risk profile. Maintaining a healthy body weight is important, as excess body fat is linked to an increased risk of colorectal cancer. Combining a healthy diet with regular physical activity is the most effective way to manage your weight and lower your risk.
Aim for at least 30 minutes of moderate-intensity activity most days of the week. Dietary adjustments should focus on increasing your intake of fiber, which is found in whole grains, fruits, and vegetables. Fiber helps keep the digestive system regular and may decrease the colon’s exposure to potential carcinogens.
Limiting the consumption of red meats, such as beef and lamb, and especially processed meats like bacon and sausages, is a recommended preventive measure. Avoiding tobacco use entirely and limiting alcohol intake are important, as both smoking and excessive alcohol consumption are risk factors for colorectal cancer. These proactive measures are beneficial for your overall health but are intended to complement, not replace, the personalized medical screening plan you establish with your healthcare provider.