Colon Cancer - Paper Example

Human beings are multicellular organisms. These cells have a life span and, therefore, can die either naturally, or secondary to injury. This injury can be from different agents which include chemicals, ionizing radiations, and oxygen radicals among others. The body has an intrinsic ability to regenerate cells to replace the dead ones in a coordinated and regulated fashion. During this process, many gene mutations occur thereby necessitating correction of the errors or killing of the cell via a natural process called apoptosis. However, this cell regeneration or growth can become dysregulated and uncontrolled giving rise to cancer due to increased chances of mutations within the tissue. The propagation of this growth is mainly because of the unmasking of oncogenes and suppression of tumor suppressor genes, which makes the human being more susceptible to tumor growth and transformation into malignancy CITATION Cro16 \l 1033 (Crosta, 2016). As a result of increased exposure to these harmful agents in this century, there has been a remarkably high increase in cases of cancer.

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Cancer has become a public health issue due to its increasing incidence and the large numbers of registered fatalities. The growth rate may be confounding to increasing screening or may truly be increasing within the population. Many factors have been attributed to the rise in cases of various cancers. The discovery of this associated factors has, thus, helped in public health education. There are different treatment modalities of these cancers. The treatment of choice also depends on various factors of the tumor, including the tumor staging, the patients age, and the presence of metastasis. From the above-stated factors, it is empirical that the early detection of the tumors has the best treatment outcome and prognosis CITATION Ken05 \l 1033 (Kendall, et al., 2005). Detection of various precancerous lesions can help in the prevention from progression to cancerous lesions. Below is a description of colon cancer, which is of a substantial public importance due to its rising incidence CITATION May16 \l 1033 (Mayo Clinic Staff, 2016).

The Colon

The colon, commonly known as the large intestines is a hollow viscus that forms part of the gastrointestinal tract. As the rest of the alimentary canal, it is involved in the passage and propulsion of remnants of digested food and waste products from the small intestines to the rectum awaiting excretion through defecation. Functionally, it is involved in the absorption of water and mineral salts from the remnants. The embryological origin of the colon is the hindgut. The mucosa lining the lumen is of columnar cells, which is of significance for the determination of the cancer type affecting the structure. The colon is divided into three major parts of clinical and surgical importance. These parts are the ascending, transverse and descending colon. The blood supply of the large intestines is the superior mesenteric artery through the right, middle and ileocolic branches, and also from the inferior mesenteric artery through its left branch. Pain within the colon is poorly localized and is traced around the umbilical region since the colon is a visceral organ and is innervated by the autonomic system. The lymphatic follows the arterial supply with nodes along the terminal arterial branches, the main branches from the aorta, and finally the preaortic nodesCITATION Sne08 \l 1033 (Snell, 2008). The understanding of the lymphatic drainage is of pathological and surgical importance in the staging of cancer and detection of metastasis. The stage of cancer affects the overall management of the patient.

Colon Cancer

Merging the terms colon and cancer, colon cancer, therefore, means uncontrolled cell growth within the large intestines. More often than not, this condition has been proved to have polyps as the precursor lesion CITATION Cro16 \l 1033 (Crosta, 2016). Polyps are masses of variable sizes that form due to abnormally increased proliferation of cells of a given tissue. The masses can either be stalked or pedunculated as a result of traction as waste food products are propelled through peristalsis down the gut to the rectum. Another variant of the polyps is the sessile polyp which lacks a definite stalk. The trigger of these polyps may be inflammation, abnormal cell growth or a familial predisposition through conditions grouped as familial polyposis syndromes. The primary culprit in the transformation into malignancy are the sessile adenomatous polyps found in the ascending colon (right side of the colon). The incidence of these adenomatous lesions rises with age. The peak incidence is between the ages of 60-70 years. Other predisposing factors include a low-fiber diet, alcohol, smoking and diet in high animal fat content. High-fiber diet reduces the transit time of the waste products through the colon thereby lessen the duration of exposure of the mucosa to harmful agents CITATION Kum13 \l 1033 (Kumar, et al., 2013).

Pathogenesis

The development of colon as in all other cancers has been associated with the accumulation of mutations within cells. Two molecular pathways have been used to explain the development of this disease. The Adenoma-carcinoma pathway involves the accumulation of mutations in the tumor suppressor genes and oncogenes, which leads to chromosomal instability. This stage progresses to localized epithelial proliferation with abnormal cells which form adenomas. These adenomas undergo dysplasia to different degrees and finally turns to invasive cancerous lesions. The second pathway involves the accumulation of errors within DNA mismatch repair genesCITATION Wil15 \l 1033 (William & Sanford, 2015). This defect in the repair genes impairs the correction of defective DNA and leads to a state of increased risk of mutations which are then propagated through all the successive cells. The abnormal cells have an invasive potential thus making the cancerous.

Pathology

Microscopically, this lesion is of columnar epithelial origin. Colon cancer may take up to four form macroscopically. These types include the annular, tubular, ulcerative and the cauliflower lesions. The cauliflower has the least potential to metastasize. The main presentation of the annular type is obstructive symptoms, whereas the other forms present with bleeding and anemia. The incidence of the lesions along the colon is 38% in the rectum, 21% in the sigmoid colon, 12% at the cecum, 5.5 on the transverse colon, 5% on the ascending colon, while the rest is distributed along the flexures CITATION Kum13 \l 1033 (Kumar, et al., 2013).

Spread

Colon cancer is a slow-growing tumor. However, it may become invasive and spread locally or to distant organs (metastasis). The tumor grows longitudinally, transverse or even radially within the substance of the colon before the invasion of surrounding structures. Spread to distant organs may follow blood vessels, lymphatics or trans-coelomic route where the lesion may seed off and fall on other organs within the peritoneal cavity. Nodal involvement is graded to measure the progression of the tumor, which may, in turn, give a direction on the type of treatment to be offered to the patient and also guide on the expected prognosis CITATION Dra16 \l 1033 (Dragovich, 2016). The invasion of nodes within the vicinity of the colon is put under the N1 category. The second stage of nodal invasion is the N2 stage where the nodes along the right, mid, left, sigmoid and ileocolic arteries. The final stage with the poorest prognosis is the N3 where nodes from the superior and inferior mesenteric arteries branch off the aorta.

Clinical presentation

Colon cancer is a condition that mainly affects individuals above the age of 50. However, younger patients can also present with it. The main complaints of patients with colon cancer are usually symptoms of intestinal obstruction. These include prolonged constipation, abdominal. Abdominal pain that is colicky in nature may also be reported. Right-sided colon cancer presents earliest. The main symptoms of the right sided lesion are associated with iron-deficiency anemia and diarrhea. On the contrary, left-sided lesions take longer to show and are mainly related to bowel habit changes. The patient may also report pencil-like stools due to narrowed lumen. The patient might also complain of a feeling of incomplete emptying on defecation. Metastatic disease may first present with liver metastasis. The symptoms for this metastasis are hepatomegaly, carcinomatosis peronei-induced ascites, and jaundice CITATION Dra16 \l 1033 (Dragovich, 2016).

In the family and social history, a history of inflammatory bowel diseases, colon cancer or familial polyposis syndrome within the nuclear or extended family may be reported. The patient may have a history or prolonged alcohol intake and smoking. Moreover, the diet of the patient may reveal continued used of low-fiber foods and high animal fat content. All these raise the suspicion of colon cancer due to a project risk and susceptibility CITATION May16 \l 1033 (Mayo Clinic Staff, 2016).

Investigations

The baseline laboratory tests for colon cancer patients include: Full hemogram (FHG), kidney function tests, liver function tests (LFTs), serum chemistries and assay for levels of serum carcinoembryonic antigen (CEA).

Moreover, other tests with high sensitivity include a guiac-based fecal test for occult blood, DNA tests and, also, fecal immunochemical test (FIT) CITATION Wil08 \l 1033 (Williams, et al., 2008 ).

Flexible sigmoidoscopy

This method is frequently used in the outpatient clinics. The procedure does not necessitate sedation. Flexible sigmoidoscopy enables visualization of the lesions size, shape, location, among other features.

Colonoscopy

Colonoscopy is the chest of choice in colon cancer. It can detect the primary cancerous lesion, synchronous polyps or even multiple carcinomatous lesions. This characteristic gives it an edge over the flexible sigmoidoscopy. On the contrary, colonoscopy involves sedation and bowel preparation.

Radiology

In cases of contraindicated colonoscopy, double contrast barium enema is indicated. A constant filling defect that is irregular in shape is the main feature in colon cancer. Other modalities of radiology include ultrasonography and spiral CT. The latter being used mainly in geriatric patients.

Management

The management of colon cancer is entirely dependent on the staging of the disease. The only treatment known to cure colorectal cancer is surgical resection. Adjuvant chemotherapy is also used to enhance the surgical treatment in stage III cancer patients. Chemotherapy is the standard modality of treatment in cases of metastatic cancer CITATION Ken05 \l 1033 (Kendall, et al., 2005).

Preoperative management of the patient by the nurse involves dietary restriction for forty-eight hours before surgery. The patient is also administered two sachets of Picolax to enable purging of the colon. A discussion on the stoma site is done with the nurse specialist in stoma care. The patient is also fitted with anti-embolus stockings. Prophylactic antibiotics and subcutaneous heparin are administered to the patient. A test of operability is also conducted to find out the fitness of the patient for surgery CITATION Wil08 \l 1033 (Williams, et al., 2008 ).

Surgically, the tumor is resected to leave an R0 margin. An R0 margin means no cancerous cells can be detected along or beyond the margins of resection of the tumor. Locoregional lymph nodes are also resected. Colonic anastomosis or stoma can then be performed with consideration the extent of colonic involvement CITATION Wil08 \l 1033 (Williams, et al., 2008 ).

References

BIBLIOGRAPHY \l 1033 Crosta, P., 2016. Colorectal Cancer. [Online] Available at: http:/...