Overview of Colorectal Cancer
Colorectal cancer is a type of malignant tumor that affects the colon or rectum, part of the large intestine. The large intestine consists of the appendix, cecum, colon, rectum, and anal canal. When a tumor develops in the colon or rectum, it is referred to as colorectal cancer. The majority of colorectal cancers are adenocarcinomas, which form in the gland cells of the mucous membranes lining the colon. Other, rarer types include lymphomas, carcinoid tumors, and leiomyosarcomas.
Types of Colorectal Cancer
Colorectal cancers primarily originate from adenomatous polyps, benign tumors that develop in the gland cells of the colon’s mucous membrane. Polyps can overgrow and eventually transform into cancer if left untreated. About 5-15% of colorectal cancers are believed to have a hereditary component. In addition to adenocarcinoma, other rare types include lymphomas (less than 1% of gastrointestinal malignancies) and neuroendocrine tumors, which may arise from neuroendocrine cells located in the appendix and rectum. Although these tumors are typically slow-growing and asymptomatic, they can metastasize in rare cases. Kaposi’s sarcoma is another rare form that can affect the colon, often seen in patients with AIDS.
Anatomy and Function of the Colon
The colon, about 150 cm long, is divided into the ascending colon, transverse colon, descending colon, and sigmoid colon, followed by the rectum and anal canal. The colon absorbs water and minerals from waste, forming solid stool. It houses over 700 types of bacteria that play a role in digesting complex carbohydrates and producing vitamins like B and K.
Statistics on Colorectal Cancer
According to the 2022 Central Cancer Registry in South Korea, colorectal cancer accounted for 11.2% of all new cancer cases in 2020, making it the third most common cancer. The incidence rate was 54.3 cases per 100,000 people, with a higher occurrence in men. Age-wise, those in their 60s represented the largest proportion of patients, followed by individuals in their 70s and 50s.
Risk Factors
Dietary Factors
A diet high in animal fats, processed meats like bacon and sausage, and low in fiber increases the risk of colorectal cancer. Some research also suggests that cooking meats at high temperatures may produce carcinogenic compounds.
Physical Inactivity and Obesity
Lack of physical activity and obesity are significant risk factors. Being overweight increases the risk of colorectal cancer by 1.5 to 3.7 times, and greater waist circumference is also linked to higher risk.
Alcohol Consumption
While studies are mixed on the relationship between alcohol and colorectal cancer, heavy drinking is suspected to increase the risk.
Genetics
Approximately 5-15% of colorectal cancer cases are thought to have a genetic component. Hereditary conditions like familial adenomatous polyposis (FAP) and hereditary non-polyposis colorectal cancer (HNPCC) significantly raise the risk of developing the disease.
Prevention and Early Detection
Dietary Prevention
Reducing the intake of high-calorie and processed foods, increasing fiber intake, and consuming more calcium-rich foods may lower the risk. Regular physical activity and moderate alcohol consumption also contribute to prevention.
Screening
For average-risk individuals, regular colonoscopies are recommended starting at age 45, every 5-10 years. High-risk groups, such as those with inflammatory bowel diseases or genetic predispositions, may need earlier and more frequent screenings.
Treatment Options
Surgical Treatment
Surgery is the primary treatment for colorectal cancer, often involving removal of the affected section of the colon along with nearby lymph nodes. In some cases, minimally invasive laparoscopic surgery is an option, which offers faster recovery and less postoperative pain.
Chemotherapy and Radiation
For patients with advanced cancer, chemotherapy, and radiation therapy are often used. Radiation is particularly common in rectal cancer to shrink tumors before surgery or to prevent recurrence.
Targeted Therapies
Newer treatments include targeted therapies like bevacizumab and cetuximab, which specifically attack cancer cells and can be combined with chemotherapy.
Living with Colorectal Cancer
Post-Surgery Lifestyle
After surgery, patients are encouraged to resume physical activity gradually and follow a nutritious diet rich in fiber to regulate bowel movements. Regular follow-ups, including colonoscopies, are crucial for monitoring recurrence.
Managing Side Effects
Chemotherapy and radiation may cause side effects such as fatigue, nausea, and diarrhea. Managing these side effects with proper diet, hydration, and medication can improve the patient's quality of life.
Prognosis and Survival Rates
The 5-year survival rate for colorectal cancer patients diagnosed between 2016 and 2020 was 74.3% in South Korea. Early detection significantly improves outcomes, with localized cases having a 94% 5-year survival rate compared to 20% for distant metastasis cases.
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