New research from Stanford University suggests most colon cancer that spreads to other parts of the body has already spread before it has been diagnosed.
In the past, researchers commonly thought metastasis (cancer spreading to other parts of the body) usually happens after a tumor has grown to a certain size, but the Stanford study contradicts this belief. According to a new study published in Nature Genetics, 80 percent of metastatic colorectal cancer spreads before the growth is larger than a poppy seed and long before it can be detected in a screening.
The researchers examined patterns of genetic mutations in colorectal tumors of 21 patients and compared them to the mutations in metastatic growths in the brain or liver. Using the data, the researchers created a timeline to predict when the mutant cell separated from the main tumor. Surprisingly, the separation occurred in early tumor development in 17 out of 21 patients.
Christina Curtis, Ph.D., Assistant Professor of Medicine and Genetics at Stanford and leader of the study, remarked, “This finding was quite surprising. In the majority of metastatic colorectal cancer patients analyzed in this study, the cancer cells had already spread and begun to grow long before the primary tumor was clinically detectable."
How will this study affect the use of traditional colon cancer detection methods like colonoscopies? Richard C. Wender, M.D., Chief Cancer Control Officer at the American Cancer Society, says the results of the Stanford study prove not all colon cancers are equal. “This doesn’t mitigate the lifesaving value of screening,” he observes, “but it does say that screening alone is not adequate to do everything possible to reduce mortality rates from colorectal cancer (Forbes).”
To gain further insight, the Stanford research team studied data from 3,000 colon cancer patients and found certain combinations of gene mutations were predictive of metastatic colorectal cancer. Not everyone with the mutation will develop metastatic colorectal cancer, but now specialists have a better indication of why colon cancer can behave so differently.
Currently, there are more than a dozen clinical trials involving new treatments for metastatic colorectal cancers, but the best way to prevent colon cancer is to know the symptoms of colon cancer, visit your doctor regularly and schedule routine colonoscopies and screenings.
The American Cancer Society suggests all adults at average risk for colorectal cancer get a baseline screening at age 45, but those with a family history of colon cancer should get tested earlier. Talk to your doctor about when you should get your first screening. If you need help finding a fellowship-trained gastroenterologist to help you make decisions for your digestive health, click here to get a list of our GI centers near you.