While some may know March is colorectal cancer awareness month, many may not know the disease is the third most common cancer in both genders and a top performer in cancer-related deaths.
And while colorectal cancer is still a disease process of the aging population, recent literature has uncovered new trends giving researchers a new field to investigate and a window to apply this information to clinical practice and improve survival.
The current risk of developing colorectal cancer is about 1 in 21 with a slightly higher risk in men than in women. The American Cancer Society has estimated about 95,520 new cases of colon and 39,910 rectal cancers will be diagnosed for 2017. Close to 50,260 people will die from their disease this year in the United States. Georgia will be among the top 10 states with the highest incidence (4,040) and cancer deaths (1,540) related to colorectal cancer.
Due to the magnitude of these numbers, health groups such as the American Society of Colon and Rectal Surgeons, American College of Gastroenterology, ACS and others have developed screening guidelines for early detection of colorectal polyps and cancer. Since the conception of these guidelines and the increased awareness and understanding that the vast majority of colorectal cancers are preceded by a polyp, the incidence of colorectal cancer has had a slow but steady decline in the overall population. This is mainly due to the increased use of screening tools in the average risk population of people 50 years of age and older.
Through a recent study published by the Journal of the National Cancer Institute, close to 500,000 patients 20 years old or older with invasive colorectal cancer were retrospectively analyzed from 1974-2013 using nine of the nation’s oldest cancer registries. The data, analyzed by complex statistical models, resulted in findings which may change the way we think about colorectal cancer and its current practices.
The study noted an increase of 1 percent to 2 percent in the incidence of colon cancer and 4 percent of rectal cancer in younger patients (younger than 50). There was also a decline in the incidence of both types of cancers during the study period in patients older than 50.
Among other investigational endpoints, tumor location was established as an important finding of this study with an increase incidence in distal colon and rectal cancers in younger patients. While this trend can be explained in part by the epidemic of obesity and low activity levels in younger patients, more research is needed to find the complex interactions between risk factors that lead to colorectal cancer.
While the direct cause-effect of colorectal cancer is not known as with most of the other cancers, several modifiable risk factors may increase the susceptibility of an individual to develop colorectal cancer. The most accepted etiologic theory is most colorectal cancers develop from a polyp, which suffers precancerous molecular changes. If it is not removed, it may become an invasive cancer. Certain dietary and environmental factors may trigger molecular changes in a genetically susceptible individual, which can lead to unregulated cell growth and cancer. The rate or speed at which these changes occur is not known, but people with well-defined genetic syndromes or carriers of certain genes can have a faster progression to colorectal cancer.
Based on recent findings, our current colorectal screening guidelines may prove to fall short in providing earlier detection for young people. However, this information will help lead the path to developing newer recommendations, which will be vital in diagnosing this disease at an earlier, more curable stage for all ages.
Fernando Aycinena is a board-certified colorectal surgeon at Longstreet Clinic in Gainesville.