As we approach March and National Colorectal Cancer Awareness Month, it’s the perfect time to schedule a colorectal cancer screening. Colorectal cancer is the second-leading cause of cancer death in the United States, and each year 140,000 people are diagnosed and over 50,000 die from it. The sad truth is that simple screens can dramatically increase the chances of catching it early when treatment options are diverse and the 5-year survival rate is 90%. If you are an adult aged 50 or older, getting screened is the simplest way to make sure you’re healthy and cancer-free.
What Does the Colon Do?
To really understand the cause and progression of colorectal cancer, it’s helpful to first understand the role of the colon for digestion. The colon is the largest part of the large intestine, which also includes the cecum, rectum and anal canal. (Sometimes the terms colon and large intestine are used interchangeably since the colon encompasses so much of the large intestine.) The colon is attached to the end of the small intestine via the cecum, and the ascending colon, transverse colon, descending colon, and sigmoid colon follows in succession and terminate at the rectum and anal canal.
In terms of the digestive system as a whole, the colon is the final stop in a somewhat elaborate process. It begins, naturally, with food being chewed up in the mouth and making its way down the esophagus to the stomach. Once in the stomach, digestive juices and a series of muscle contractions work to break down the food into a semi-liquid substance called chyme. The chyme then moves to the small intestine where additional digestive juices with digestive enzymes break it down even further and allow nutritional components to be absorbed by the small intestine and then carried around the body by the bloodstream.
After the digestive process in the small intestine is complete, the resulting mix of waste materials moves into the colon. Even though the colon doesn’t technically play a role in the digestion of nutrients, the gut microbiota present in the colon can utilize the waste materials to synthesize valuable vitamins. Primarily, though, the colon serves to absorb water and electrolytes from the waste. And by the time this material has reached the sigmoid colon, the mostly solid stool has formed that will be ready to be passed through the rectum and anus.
What is Colorectal Cancer?
Like any cancer, colorectal cancer is a condition where an abnormal overgrowth of mutated cells grows and can eventually spread throughout the body, causing substantial damage to tissues and organs. In this case, cancer begins in the colon or rectum; both types are often grouped together due to their similarity and proximity. As noted earlier, colorectal cancer affects tens of thousands of Americans every year, typically those are aged 50 or older.
In the vast majority of cases, colorectal cancer begins with small growths on the inner lining of the colon called polyps. These fleshy masses are often benign at first, but they can become cancerous over time. Some polyps, such as the inflammatory variety that can accompany irritable bowel syndrome, are very unlikely to lead to cancer; hyperplastic polyps are another type that has low malignancy potential. One type that is considered precancerous (and thus likely to lead to cancer) is an adenomatous polyp, and its subtype villous adenoma is the most likely to lead to cancer.
The symptoms of colorectal cancer often only present after cancer has progressed or spread to other areas, so they aren’t very useful as diagnostic tools. Additionally, many of the symptoms are shared by other gastrointestinal diseases like irritable bowel syndrome, inflammatory bowel disease, or hemorrhoids. But when symptoms of colorectal cancer do appear, they typically present in the following ways:
- Bowel habit changes lasting more than a few days
- Rectal bleeding
- Bloody stool
- Unexpected weight loss
- Abdominal pain or cramping
What is the Cause of Colorectal Cancer?
Unfortunately, doctors don’t fully understand the cause of colorectal cancer or cancer in general. Some research has shown strong links between certain risk factors and colorectal cancer, but the full story of their impact is still being studied. What is known with a fair amount of confidence, however, is that cancer starts because of mutations in the DNA of certain cells. Oncogenes provide cells with instruction for cell division and growth, and tumor suppressor genes regulate the potential for cellular overgrowth; mutations to both types of genes are thought to be involved at the beginning of cancerous growth.
Where the research starts to get unclear is why these mutations occur in the first place. One possibility is that they are inherited from ancestors; an example of this is familial adenomatous polyposis (FAP), a condition that can lead to colorectal cancer due to the presence of numerous adenomatous polyps. A more likely scenario is that the mutations aren’t passed on and instead can be acquired during the course of life. In both cases, a type of tumor suppressor gene called APC seems to be involved in the initial mutation; this gene is likely because of its function as a “brake” on cellular overgrowth.
Risk Factors for Colorectal Cancer
The risk factors for colorectal cancer are important considerations, especially when a doctor needs to determine the frequency of testing as people get older. Those with higher risk are encouraged to get tested earlier (typically age 45) and more often. The main risk factors identified by the American Cancer Society are divided into factors one can control and factors one can’t control:
- Factors that can be controlled
- Being obese or overweight
- Having a diet high in red meat or processed meats
- Being a smoker
- Being a heavy drinker
- Being inactive or not exercising regularly
- Factors that can’t be control
- Age (most cases are in patients 50 years or older)
- Being African American (highest rate among racial groups)
- Being Jewish of Eastern European descent (highest rate among ethnic groups)
- Having an inherited condition like FAP
- Having type 2 diabetes
- Having a family or personal history of colorectal cancer
- Having inflammatory bowel disease
Treatment Options for Colorectal Cancer
In order to organize options for treatment and the progression of cancer in patients, doctors use a staging system. Treatment varies based on the stage of development, and it runs from stage 0 (very early) to stage IV (very advanced):
- Stage 0
- Status: Polyps or small tumors exist in the mucosal lining of the colon
- Treatment: Surgery is the main treatment to remove the polyps, tumors, or a portion of the colon if necessary
- Stage I
- Status: Cancerous cells have grown into the wall of the colon, but they still haven’t spread to the lymph nodes or elsewhere in the body
- Treatment: Surgery is still the main treatment to remove any parts of the colon that are necessary
- Stage II
- Status: Cancerous cells have spread through the wall of the colon and possibly to nearby tissues, but they still haven’t reached the lymph nodes
- Treatment: Depending on the nature of how the cancerous cells have spread, a combination of surgery and chemotherapy may be used
- Stage III
- Status: Cancerous cells have spread to the lymph nodes but not elsewhere in the body
- Treatment: Surgery, chemotherapy, and radiation therapy are options based on the amount of spread and whether or not the patient is healthy enough for surgery
- Stage IV
- Status: Cancerous cells have spread beyond the colon to distant parts of the body
- Treatment: Chemotherapy is the main treatment with surgery as necessary
It’s Time to Schedule a Screening
The goal of National Colorectal Cancer Awareness Month is to raise awareness of both colorectal cancer and the importance of getting screened early. If you are 45-50 years old and have yet to be screened for colorectal cancer, contact Savannah Gastro to make an appointment. Our board-certified gastroenterologists are passionate about making sure that any incidences of colorectal cancer are caught early so that patients have the best chance to get the treatment they need.