Colon Health

By Mel Ona, M.D.

March is Colorectal Cancer Awareness Month. Colorectal cancer is the second most lethal cancer in men and women in the United States. Imagine Aloha Stadium at capacity (50,000 seats) – that’s how many people die of colorectal cancer every year! Gastroenterologist, Dr. Mel Ona, answers common questions about colorectal cancer.

What is colorectal cancer?
Colorectal cancer is a malignant tumor in the colon (large intestine) or rectum. Cancer occurs when cells grow out of control and invade through normal body tissue and possibly spread throughout the body (metastasis).

What causes colorectal cancer?
While some cancers are caused by genetic mutations that are passed through family generations, most colorectal cancers start as small pre-cancerous growths or polyps. If these pre-cancerous polyps grow and invade the deeper layers of the colon or rectum, then they are considered colorectal cancer.

What are symptoms of colorectal cancer?
Symptoms may include change in bowel habits, bleeding from the rectum, unexplained weight loss, or abdominal pain. However, you may have no symptoms particularly with early stages of colorectal cancer.

What can I do to reduce the risk for colorectal cancer?
Stop smoking, avoid drinking excessive alcohol, lose excess body fat, be physically active, consume less processed foods, and get screened!

When should I get screened for colorectal cancer?

If you have no symptoms and no specific risk factors such as family history of colorectal cancer, then screening is performed at age 50. If you are Black/African-American, screening is recommended at age 45. If you have specific risk factors (personal history of inflammatory bowel disease such as ulcerative colitis or Crohn disease, family history of colorectal cancer, family history of colon polyps) then you should be screened earlier.

What are different screening options for colorectal cancer?

  • Colonoscopy every 10 years 
  • Fecal Immunochemical Testing (FIT) for occult blood in stool every year 
  • Sigmoidoscopy every 5 years with FIT every year 
  • FIT with stool DNA every three years 
  • CT colonography every five years.

What’s the best screening test for colorectal cancer?
The one that gets done!

How does a colonoscopy prevent colorectal cancer?

Most colorectal cancers start as polyps that grow over time. During colonoscopy, a flexible tube with a video camera is inserted into the rectum and the entire colon is carefully evaluated. We can detect precancerous polyps and remove them before they become cancer.

Is colonoscopy safe?
Colonoscopy is a safe procedure with a complication rate of less than ½ of one percent. Adverse events may include bleeding, infection, perforation (injury), or anesthesia complications.

Can colorectal cancer be cured?
Colorectal cancer can be treated with chemotherapy, radiation, and/or surgery. Most clinicians refer to a five-year survival statistic when discussing prognosis. If colorectal cancer is diagnosed early when the tumor is localized in the large intestine or rectum only, the five-year survival is 92%. In other words, 92% of people who are diagnosed with localized cancer (stage I) are still alive five years after initial diagnosis. Those with distant metastases (stage IV) or tumor that has traveled through the bloodstream or through lymph nodes and spread from the colon or rectum to other organs such as lung or liver have approximately 12% to 14% five-year survival.

I know someone who got a colonoscopy and said it was painful. Is this true?
Colonoscopy is the most accurate method for detecting polyps and preventing colorectal cancer (by removing precancerous polyps). There are nearly 22 million people in the U.S. ages 50 to 75 who have not yet been screened for colorectal cancer. If you want more information about colonoscopy, please visit my YouTube channel (Dr. Mel Ona) to watch me undergo the procedure without sedation. (Spoiler alert: it was painless!) Again, the best screening test is the one that gets done!

DR. MEL ONA is a gastroenterologist in private practice with offices in Kapolei and Honolulu. He is a member of the Philippine Medical Associate of Hawaii and is the author of several books related to medical education and nutrition/fitness. Website:

Leave a Reply

Your email address will not be published.

This site uses Akismet to reduce spam. Learn how your comment data is processed.