Colorectal cancer is often linked to a combination of lifestyle and genetic factors, including diet, obesity, smoking, alcohol consumption and lack of physical activity. However, genetics can also play a critical role, with some individuals inheriting a higher risk of developing the disease.
Its hereditary risk remains a lesser-known aspect. According to Dr. Zee Ying Kiat, a distinguished oncologist from Parkway Cancer Center, said that about 5 to 10 percent of colorectal cancer cases are hereditary, passed down through faulty genes that increase a person’s risk of developing the disease.
Can cancer be inherited? For most people, colorectal cancer develops gradually due to acquired genetic mutations — DNA changes that happen over time due to lifestyle, environment or other unknown factors. But for a small percentage of individuals, the risk is written in their genes from birth.
“Some people develop polyps at an early age, no matter how healthy their lifestyle is, simply because they were born with a faulty gene,” Dr. Zee explained. “They have a hereditary predisposition to colorectal cancer. If you have a family history of colorectal cancer, it’s crucial to consult a doctor early.”
To understand this better, it helps to know how DNA mutations work. Our DNA contains genes that control how cells grow, divide and die. Oncogenes encourage cell growth and division. Tumor suppressor genes keep cell growth under control and signal when a cell should die.
When DNA mutations activate oncogenes or turn off tumor suppressor genes, cells start growing uncontrollably leading to cancer. While most of these mutations happen randomly over a person’s lifetime, inherited mutations are present from birth and increase the likelihood of cancer forming much earlier than usual.
Genetic testing can detect these inherited mutations, allowing high-risk individuals to take preventive steps before cancer even starts.
Dr. Zee stressed that early detection is the key to beating colorectal cancer. Regular screening, such as colonoscopies, can identify and remove polyps before they become cancerous. In fact, studies show that early detection increases survival rates significantly, with localized colorectal cancers having a 5-year survival rate of up to 90 percent.
According to Dr. Zee, with increased awareness and screening efforts, colorectal cancer deaths have declined over the past 15 years. Advances in treatment also mean that patients diagnosed early have a much better chance of survival and even a complete cure.
“Even if you have no symptoms or family history, screening is still important,” he emphasized. “The majority of colorectal cancer cases occur due to genetic changes acquired during a person’s lifetime and we don’t always know what triggers them.”
Given these uncertainties, routine screenings remain the best way to detect and prevent colorectal cancer before it’s too late. Aside from screenings, Dr. Zee also highlighted that vaccinations — applicable to certain types of cancer, like the HPV vaccine for cervical cancer — can help provide protection against infections that most commonly cause cancer.
While genetics may influence colorectal cancer risk, adopting a healthier lifestyle can also play a crucial role in prevention. Quitting smoking reduces the risk of tobacco-related cancers and HPV infection, while moderating alcohol intake lowers the chances of liver disease, cirrhosis and hepatitis B or C. Maintaining a balanced diet, staying physically active and managing weight can also help minimize cancer risks across the board.
Whether inherited or acquired, cancer is best fought with knowledge, vigilance and proactive healthcare. If you or a loved one has a family history of colorectal cancer or if you’re over 50, consider speaking to a doctor about genetic counseling or screening — it could be a life-saving step.