What Causes Colon Cancer?

While there are several lifestyle factors that play a role in the genesis of colon cancer, there are a series of stepwise genetic mutations that lead to this disease. Generally speaking, colon cancer develops over a long period of time. Most times we can catch colon cancer before it develops with various screening measures, including a colonoscopy. Let’s find out why colon cancer takes so long to develop and how we can use this to our advantage.

Colon cancer develops when the chromosomes in the cells that make up our colon lining become unstable. A chromosome contains the genetic material of our bodies. In fact, our DNA is densely packed and folded into a structure called a chromosome. With colon cancer, the cells of our intestinal lining can lose a portion of or a complete copy of a chromosome. Approximately 85% of all colon cancers are due to an instability in the DNA, or chromosomes, that make up our colon lining. (1) Many genetic mutations need to occur in a stepwise fashion over time for colon cancer to develop. When these mutations build up over time, a small section of our normal colon lining can turn into an adenoma. Once an adenoma develops, colon cancer is in its infancy. Therefore, this term adenoma is very important. Let’s find out what it means.

An adenoma can be thought of as the “middle-man” in the development of colon cancer. Adenomas can turn into cancer within 7 – 10 years. The goal of colonoscopy is to detect adenomas and remove them before they become cancer. Remember, up to half of men and women will have adenomas found on colonoscopy. Therefore, adenomas are very common.  Yet, only about 5% of adenomas will turn into cancer over time. (2) The most effective way to treat colon cancer is to prevent this disease with the removal of adenomas. We should not wait until cancer has developed. At which time, surgery and chemotherapy are our only options. This is where an ounce of prevention is worth a pound of cure.

When we look at the development of colon, we know that there are a series of mutations that need to take place before an adenoma is develop. An adenoma can be seen as the birth of colon cancer. In 7-10 years, this adenoma will grow up to become cancer. With more time, colon cancer will mature to spread throughout the body. Remember, although a small percentage of adenomas will turn into cancer, adenomas are so common that this small number adds up over time. As a result, colon cancer has become more frequent that we realize. Defeat colon cancer in its infancy with a colonoscopy and removal of adenomas. Do not wait until disease has become fully grown and mature. Use the wisdom of prevention to your advantage.

REFERENCES 1. In Alguire, P. C., & American College of Physicians, (2018). MKSAP 18: Medical knowledge self-assessment program. 2. Heitman SJ, Ronksley PE, Hilsden RJ, Manns BJ, Rostom A, Hemmelgarn BR. Prevalence of adenomas and colorectal cancer in average risk individuals: a systematic review and meta-analysis. Clin Gastroenterol Hepatol. 2009 Dec;7(12):1272-8.