Colon Cancer vs Colorectal Cancer
Large bowel is medically known as the colon. The colon consists of the caecum, ascending colon, transverse colon, descending colon and sigmoid colon. The sigmoid colon is continuous with the rectum. Rectum and the colon share many microscopic and macroscopic features. Therefore, cancers at the colon affect the rectum just as similarly. Colon cancer and colorectal cancer are simply two names. When the cancer is limited to the colon it is a colon cancer. When the cancer involves the rectum as well as the colon it is a colorectal cancer. Here, we will talk about colon / colorectal cancer in detail, highlighting their clinical features, symptoms, causes, investigation and diagnosis, prognosis, and also the course of treatment they require.
Colorectal cancers present with bleeding per rectum, feeling of incomplete evacuation, alternative constipation and diarrhea. There may be associated systemic features such as lethargy, wasting, loss of appetite and loss of weight.
There are many risk factors for colorectal cancers. Inflammatory bowel diseases (IBD) lead to cancer due to a high rate of cell division and repair. Genetics play a key role in carcinogenesis because with rapid cell division the chance of cancer gene activation is high. First degree relatives with colorectal cancers suggest a significantly higher chance of getting colorectal cancers. There are genes called proto-oncogenes, which result in malignancies if a genetic abnormality transforms them into oncogenes.
When a patient presents with such symptoms, a sigmoidoscopy or a colonoscopy is indicated. Using the scope, a small piece of the growth is removed to be studied under the microscope. Cancer spread should be assessed to decide on treatment methods. Imaging studies like magnetic resonance imaging (MRI), computed tomography, and ultrasound scans help assess the local and distant spread. Other routine investigations should also be done in order to assess the fitness for surgery and other relevant factors. Full blood count may show anemia. Serum electrolytes, blooard sug levels, liver and renal function should be optimized before surgical procedures. There are special tumor markers that be used to detect the presence of a colorectal cancer. Carcinoembryonic antigen is one such investigation. Most of the colorectal cancers are adenocarcinomas.
Colorectal cancers are preventable. High intake of fruits and vegetables, low intake of red meat and regular physical activity significantly reduce the colorectal cancer risk. Aspirin, celecoxib, calcium and vitamin D reduce the colorectal cancer risk. Familial adenomatous polyposis increases the risk of colorectal cancer. Flexible sigmoidoscopy is a reliable investigation to screen for suspicious lesions in the colon.
Treatment plan varies according to the stage of the cancer. Currently used classification for colorectal cancer staging is the Duke Classification. This classification takes into consideration the presence or absence of metastasis, regional lymph node, and local invasion.
For localized cancers, the curative treatment option is complete surgical resection with adequate margins to either side of the lesion. Localized resection of a large bowel segment can be done via laparoscopy and laparotomy. If the cancer has infiltrated lymph nodes, chemotherapy increases life expectancy. Fluorouracil and Oxaliplatin are two commonly used chemotherapeutic agents. Radiation is also of significant benefit in advanced disease.
Colon cancer and colorectal cancer are the same. When the cancer is limited to the large bowel, it is called a colon cancer while the cancer involving the large bowel, as well as the rectum, is called a colorectal cancer.