Colorectal Cancer: Drugs Administered, Mechanism of Action, and Detection Technologies

Running header: COLORECTAL CANCER 1
Colorectal cancer
Student’s name
Institutional

Colorectal cancer
Colon and rectum tumors are mostly common; the colorectal area is now the third most common
site of cancer cases and deaths globally (Bailey and You, 2014). Cancer of the colon and rectum
develops from the epithelial lining of the intestine. It usually begins as a benign polyp which
later becomes a malignant which penetrates and destroys the normal tissues. The frequency of
occurrence is highest for individuals older than 85 years of age and is higher for individuals who
have had a history of colon cancer in the family. The specific cause of colorectal cancer is still
not known but the risk factors have been identified. The risk factors include breast cancer in
women, high fat and beef intake, and medical record of inflammatory bowel disease and lastly
family history of colon cancer (Ponteri-lewis, 2013). If this disease is detected early and treated,
it could save three people out of four with colon cancer. This essay is going to talk about the
drugs administered to Nelly their mechanism of action and lastly the technologies used to detect
colorectal cancer.
Drugs administered
Colorectal cancer therapy depends on the stage of the disease and it usually done by removal of
the tumor through surgery, adjuvant therapy and supportive therapy. Nellie had a stage IVA
cancer and she was referred to a colonoscopy and it was discovered that nelly had polyps in the
colon which were surgically removed. She later came for adjuvant therapy which included 5-
Fluorouracil, Irinotecan and lastly Oxaliplatin. This kind of therapy was used to reduce the
chances of the cancer coming back after surgery. Pain medication was initiated after targeted
radiotherapy failed to shrink the tumor, the severe back pain was as a result of cancer that had
spread to the spinal cord and was compressing the spinal cord. Pain medication included
paracetamol and morphine. Spinal tumor increased each day which caused more pain and the

dose of morphine was difficult to titrate due to severe side effects it caused. End of life pathway
drugs were commenced which included levomepromazine and sublingual clonazepam.
Mechanism of action
5- Fluorouracil (5-FU) is an antimetabolite which exerts its action on cells undergoing cycling. It
kills tumor cells which are in the cycling and resting phase of the cell cycle. In the cell
fluorouracil is changed to 5- fluoro-2-deoxyuridine-5-monophosphate (5-FdUMP), which causes
the suppression of thymidylate synthase which later leads to the death of thymineless of cells.
DNA synthesis is inhibited by the penetration of FdUMP. RNA synthesis and function is
inhibited by 5-fluorouradine-5-triphosphate (FUTP) which is a fluorouracil metabolite. In the
tumor cell the mechanism of resistance include an increased thymidylate synthase activity, a
reduced activation of 5-FU, and lastly a decreased drug sensitivity of this enzyme. As a result the
cell is unable to divide and dies.
Irinotecan is a plant derived cell cycle specific (CCS) drugs which is found in the camptothecins
group. It is converted to an active form SN-38 which requires carboxyl esterase (Huangg,
Wuerzberger-Davis and Seufzer, 2012). it inhibits topoisomerase 1 activity hence causing
damage to the DNA. The DNA is damaged by an inhibiting enzyme that cuts and the single
DNA strands during the normal DNA repair process (Maureen, Beidler and cheng, 2013).
Oxaliplatin is a chemotherapeutic agent that contains 1, 2- diaminocyclohexane ligand. Like the
other platinum based compounds it exerts its effect by damaging the DNA and also by inhibition
of RNA synthesis. It induces three types of links which include DNA intra-strand link, DNA
inter-strand crosslinks and DNA-protein crosslinks. Intra-strand links act by the induction of
DNA lesions while the inter-strand link are said to bring about the cytotoxicity of cisplatin. The