A review of colorectal cancer and its treatment

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Szerzők
Mukan, Shroutee
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Absztrakt

Colorectal cancer is the third most common cancer affecting both man and woman and it is ranked as the third leading cause of death in the United States. It is due to an abnormal growth of cells that are able to invade or to spread to other parts of the body. Symptoms associated with colorectal cancers are alterations in the bowel habits, bloody stool, abdominal discomfort, anemia, unexplained weight loss and fatigue. Many factors are attributed to colorectal cancer such as genetics, age, bad social habits (smoking and alcohol), diabetes, obesity, inflammatory bowel diseases (such as Ulcerative Colitis and Chron’s disease) and inherited conditions such as familial adenomatous polyposis and hereditary non-polyposis colon cancer. Screening of people has shown to detect assymptomatic early stage malignancy and it has shown to decrease the mortality rate. The main tests used in the screening of colorectal cancer are the fecal occult blood testing, flexible sigmoidoscopy and colonoscopy. If the fecal occult blood testing shows abnormal results, patient is referred for a follow-up colonoscopy examination. Tumour markers such as carcinoembryonic antigen (CEA) and CA 19-9 are associated with CRC. CEA levels should be obtained preoperatively. Diagnosis is often made by colonoscopy which is a procedure involving visualisation of the entire colon prior to surgery and it has prime importance in localising the tumor and characterising the lesion. If colonoscopy cannot be performed, barium enema or CT or MR colonography can be used. There are various treatment options depending on the stage of the CRC namely surgery, chemotherapy, targeted therapy and radiation therapy. There are several surgical treatments such as laparoscopic assisted colectomy, polypectomy and protectomy for localised cancer. The prognosis of the newly diagnosed colorectal cancer patient is determined by the clinicopathologic stage of the disease. Most commonly used chemotherapeutic drugs are the 5- Fluorouracil, Leucovorin, Capecitabine , Irinotecan, Oxaliplatin, Cetuximab and Panitumumab. 5-fluorouracil is an antimetabolite that works by irreversibly inhibiting thymidilate synthase and it is usually given together with vitamin-like drug leucovorin (folinic acid), Capecitabine is a prodrug and is converted to 5-fluorouracil, a fluoropyrimidine carbamate with antineoplastic activity, Irinotecan is an inhibitor of topoisomerase1 and it inhibits the DNA from unwinding, Oxaliplatin is a platinum based antineoplastic agent having a diaminocyclohexane (DACH) ring and the two epidermal growth factor receptors inhibitors such as Cetuximab and panitumumab. Cetuximab being is an IgG1 chimeric monoclonal antibody and panitumumab is an IgG2 fully human monoclonal antibody. Neoadjuvant (preoperative) chemotherapy is a common approach for locally advanced colorectal cancer and it includes the delivery of chemotherapy at full systemic doses and its beneficial for the early treatment of micrometastatic disease,mostly used combination is the 12 weeks of capecitabine and oxaliplatin (XELOX). Adjuvant (postoperative) chemotherapy namely the FOLFOX (5-FU , leucovorin and oxaliplatin) is used in patients having undergone a resection of the colon and it aims at eradicating micrometastases, the treatment options includes a combination of chemotherapy drugs which are given intravenously or in specific days . Adjuvant chemotherapy is mostly used for stage II and III of colorectal cancers. For cancers that have spread the most common combination of treatment are FOLFOX, FOLFIRI (5-FU, leucovorin and irinotecan) and XELOX (Capecitabine and oxaliplatin). Colorectal cancers gives metatastasis mostly to the liver and to the lung, and ultrasound is required every 3 months for a period of 2 years to monitor any liver metastasis.

Leírás
Kulcsszavak
Colorectal
Forrás