Colon cancer starts from epithelial cells lining the rectum and colon, with mushroom-shaped adenomatous polyps of glandular origins in the appendix, rectum, or colon, and is the fourth most common form of the disease in the United States. Colon cancer may spread to regional lymph nodes, metastasize to distant sites, and cause mutations to the Wnt signaling pathway proteins typically damaging the tumor suppressing adenomatous polyposis coli gene brake that helps prevent cells from becoming cancerous, control beta-catenin proteins that maintain and create epithelial cell layers, regulate cell growths, and assist cellular adhesions.
Possibly based on the location of the tumor in the bowels, and metastatic spread to other organs, contributing factors leading to contracting colon cancer include such things as the age of the patient, diabetes, consuming alcohol (especially beer), high fat and cholesterol diets, ethnicity, family histories, gender, genetic mutations, sedentary lifestyles, polyps, smoking cigarettes, the Inflammatory Bowel Disease, women who have had previous cancer of the uterus, breast, or ovaries, the Gardner Syndrome, Familial Colorectal Polyposis, lithocholic bile acid, the Human Papilloma Virus, ulcerated colitis, Primary Sclerasing Cholangitis, chronic liver diseases, low levels of selenium, living in industrialized countries, hormone replacement therapies, Tamoxifen, oral contraceptives, and Vitamin B6.
Localized symptoms of colon cancer may occur if the tumor is found near the anus and include new on-set constipation or diarrhea, changes in bowel habits, rectal tenesmus, stool shape changes, bright red blood in the stools, lower gastrointestinal bleeding, melena, black stools, upper gastrointestinal bleeding, bowel obstructions, severe abdominal pains, abdominal distentions, bowel perforations, peritonitis, hydronephrosis, renal pelvis calyces dilations, bladder invasions, air or blood in the urine, female reproductive tract invasions, and vaginal discharges.
Whole body, or constitutional, symptoms of colon cancer may include iron deficiency anemia, chronic occult bleeding, palpitations, excessive fatigue, pale skin coloring, unexplained fevers, and a variety of paraneoplastic syndromes such as deep vein thrombosis.
Colon cancer may be diagnosed through such measures as fecal occult blood tests, digital rectal exams, sigmoidoscopies, colonoscopies, biopsies, tissue examinations, Double Contrast Barium Enemas, computed axial tomographies, Virtual Colonoscopies, assorted blood tests, various genetic tests, Positron Emission Tomographies, whole body PET screenings, stool DNA tests, High C-Reactive protein levels, and miRNA profiling based screenings.
Colon cancer may be treated by various surgeries, chemotherapies, radiotherapies, palliative resections, isolated liver metastasis removals, fecal diversions, tumor bypasses, laparoscopic assisted colectomies, physical fitness, good nutrition, and Vitamin D.
Approved by the US Food and Drug Administration medications given with chemotherapies that may be beneficial to colon cancer patients include Oxaliplatin, 5-Fluorouracil, folinic acid, Leucovorin, Capecitabine, Tegafur-Uracil, Panitumumab, Bevacizumab, Cetuximab, Erlatinib Hydrochloride, Bortezomib, Gefitinib, and Oblimersen.
Colon cancer is staged by the number of lymph nodes involved, distant metastasis, and the extent of local invasion by the disease, which can only be determined after surgery has been performed on the patient, and may involve CT scans, PET scans, abdominal ultrasounds, endoscopic ultrasounds, and colonoscopic polypectomies, with the American Joint Committee on Cancer’s Tumors/Nodes/Metastasis Staging System the most commonly used method.
Another staging system, the Dukes Classification System, stages colon cancer based on the tumor being confined to the intestinal wall, the tumor invading through the intestinal wall, lymph node involvement, and distant metastasis, while the Astler-Coller System stages colon cancer based on the tumor being limited to the mucosa, carcinoma in situ, the tumor grows through the muscularis mucosae but not through the muscularis propria, the tumor grows beyond the muscularis propria, regional lymph node metastasis, and distant metastasis.
The American Society of Clinical Oncology, and the National Comprehensive Cancer Network, recommend colon cancer follow-ups for physical examinations, carcinoembryonic antigen blood level measurements, and medical histories be performed every three to six months for two years, and every six months for five years, to monitor any tumors or metastasis that may occur after the initial treatment procedures have been conducted but did not originate from the original cancer. They also recommend a colonoscopy after one year, and CT scans of the abdomen, pelvis, and chest annually for up to three years for high risk patients.
This Article was compiled from several websites that provide much more information about colon cancer including: