pathoscribe

Written by Diya Desikan | Art by Diya Desikan

Colorectal cancer is the leading cause of cancer deaths in the United States. It is a disease in which colon or rectum cells rapidly grow, creating tumors that invade and destroy healthy cells. This March is recognized as a month to increase public awareness and mitigate stigma surrounding colorectal cancer. Colorectal cancer is a highly prevalent disease, affecting an estimated 1 in 23 men and 1 in 25 women at some level, as reported by the American Cancer Society. Usually, colorectal cancer only presents itself in those over 45, which is why regular screening is mandatory at that age, but still occurs in younger demographic groups, making it crucial to be aware of its symptoms.

This cancer can be spotted through symptoms such as a change in bowel habits, blood in stool, diarrhea, constipation, an insistent feeling that the bowel is not empty, abdominal pain that lingers, or unexplained weight loss. If these symptoms are prevalent, visit a doctor or another professional. 

The chances of having colorectal cancer can increase with age, experiencing inflammatory bowel disease (see article: IBS: More than Diarrhea), family history of such cancer, lack of physical activity, low fiber and high-fat diet, obesity, alcohol consumption, tobacco use, and cancer radiation therapy. 

How exactly does colorectal cancer occur? Colorectal cancer refers to both colon and rectal cancer. Both cancers have the same symptoms and prognosis, but the difference lies in where the cancer spreads. 

The colon and rectum form the large intestine, a part of the gastrointestinal (GI) or digestive system. The colon is around five feet long and has two main parts — the proximal and distal colons. The proximal colon contains the ascending colon, where the undigested food from the small intestine goes through, and the transverse colon, which lies across the body, connects the ascending colon to the descending colon from left to right. The distal colon is made of the descending colon and the sigmoid colon, which joins the rectum and connects it to the anus. 

Cancer develops due to an abnormal change in DNA. DNA holds instructions for cells, and this change tells the cells to multiply rapidly. Usually, cells form and die at a constant rate. If cells develop too fast, more cells are forming than dying. This excess of cells becomes a tumor that kills healthy cells. In colorectal cancer, this growth of cells occurs on the inner lining of the rectum or the colon and forms polyps.

Polyps are usually benign, or non-cancerous, but they can become cancerous. Adenomatous polyps are an example of cancerous polyps. Tubular adenomatous polyps are the most common, while villous adenomatous polyps are more likely to become cancerous. Hyperplasticity and inflammatory polyps are usually not precancerous but may require screening with a colonoscopy if the polyp is larger than one centimeter. Sessile serrated polyps and traditional serrated adenomas are treated like adenomatous polyps and have higher chances of developing cancer. If a polyp is larger than one centimeter or contains dysplasia, in which cells look abnormal, or if there are more than three polyps found, there is a higher chance that these polyps are cancerous. 

These polyps grow into the wall of the colon, resulting in colon cancer, or the rectum, leading to rectal cancer. They start in the innermost layer, the mucosa, and can extend outward to all the layers—mucosa, submucosa, thick muscle layers, subserosa, and the serosa. Polyps grow into the blood and lymph vessels, which carry waste and fluid and travel to nearby lymph nodes or other parts of the body. This process of moving cancer cells to other body parts is called metastasis. 

The types of colon cancers include adenocarcinomas, carcinoid tumors, gastrointestinal stromal tumors (GISTs), lymphomas, and sarcomas. Adenocarcinoma is the most common type of colon cancer and starts in the cells that produce mucus that lubricates the inside of the colon and the rectum. Carcinoid tumors stem from cells that produce hormones in the intestine. GISTs start from the nerve cells in the gastrointestinal tract. Some GISTs are benign. Lymphomas are immune system cell cancers that begin in the lymph nodes and travel to the colon, rectum, or other organs. Sarcomas are the rarest type of colon cancer and can start in blood vessels or other connective tissues in the walls of the colon or rectum. 

Colorectal cancer has both local and systemic treatments. Local treatments directly treat the tumor without affecting the body and are most beneficial during the early stages of cancer. These treatments include surgery and radiation therapy. The systemic treatments reach the cells throughout the body, and their treatments include chemotherapy, drugs, and immunotherapy. 

While colorectal cancer may seem like an unpleasant topic to discuss, it is crucial to be aware of its prevalence and impacts. By promoting awareness and reducing the stigma surrounding this disease, we can build a supportive community for those experiencing colorectal cancer! 

Works Cited:

“What Is Colorectal Cancer?” Centers for Disease Control and Prevention, Centers for Disease Control and Prevention, 23 Feb. 2023, http://www.cdc.gov/cancer/colorectal/basic_info/what-is-colorectal-cancer.htm#:~:text=Colorectal%20cancer%20is%20a%20disease,large%20intestine%20or%20large%20bowel. 

“What Is Colorectal Cancer?: How Does Colorectal Cancer Start?” How Does Colorectal Cancer Start? | American Cancer Society, http://www.cancer.org/cancer/types/colon-rectal-cancer/about/what-is-colorectal-cancer.html. Accessed 23 Mar. 2024. 

“What Are the Risk Factors for Colorectal Cancer?” Centers for Disease Control and Prevention, Centers for Disease Control and Prevention, 23 Feb. 2023, http://www.cdc.gov/cancer/colorectal/basic_info/risk_factors.htm. 

“What Are the Symptoms of Colorectal Cancer?” Centers for Disease Control and Prevention, Centers for Disease Control and Prevention, 23 Feb. 2023, http://www.cdc.gov/cancer/colorectal/basic_info/symptoms.htm. 

“Colon and Rectal Cancer Guide: If You Have Colorectal Cancer.” Colon and Rectal Cancer Guide | If You Have Colorectal Cancer | American Cancer Society, http://www.cancer.org/cancer/types/colon-rectal-cancer/if-you-have-colon-rectal-cancer.html. Accessed 23 Mar. 2024. 

“Colorectal Cancer Treatment: How to Treat Colorectal Cancer.” Colorectal Cancer Treatment | How to Treat Colorectal Cancer | American Cancer Society, http://www.cancer.org/cancer/types/colon-rectal-cancer/treating.html. Accessed 23 Mar. 2024.