Disorders of the Gastrointestinal System, 2nd Edition
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● Molecular testing of the tumor : Identifying the tumor type at the molecular level has recently gained traction and is proving to be an effective way to guide the treatment of cancers. Therapy can be targeted to the specific type of tumor present, increasing the chances that it will be effective. Surgery is the most effective method for curing early-stage colorectal cancer. In very early cases, polyp removal and anal- ysis of adjacent tissues to determine if the disease is localized may be sufficient. The mucosal lining surrounding the polyp can also be removed if it is affected. Lymph nodes may also be removed to deter- mine if cancer has invaded the lymphatic system (Dragovich, 2022). Depending on the extent of the disease, colon resec- tion (removal of parts of the colon) may be necessary. In some cases, colostomy (complete colon removal) is necessary, and a permanent stoma with an external collection device may be placed (Dragov- ich, 2022). Metastatic disease or inoperable tu - mors indicate the need for chemother- apy. Recent studies have shown a 30% decrease in cancer recurrence at the five-year mark when 5-fluorouracil with leucovorin or levamisole chemotherapy agents are used (Dragovich, 2022). Add- ing oxaliplatin to the treatment regimen has also shown promise and decreased recurrence rates (Rodriguez et al., 2022). Ablation may also be an option in the treatment of metastatic disease. This is done by using cryotherapy, which comes with a higher risk of mortality, or radiofre- quency, which does not have a high risk of mortality but a higher risk of recurrence (Dragovich, 2022).
In addition to a history and physical, several diagnostic tests are conducted to identify colorectal cancer (Dragovich, 2022): ● Scopes : Proctoscopy, sigmoidoscopy, and colonoscopy are performed to visualize tumors, detect and remove polyps, and biopsy suspicious tissues and lesions. The colonoscopy is preferable because this allows for visualization of the entire large bowel. ● CT and MRI, imaging of the pelvis and abdomen : CT and MRI scans are generally conducted to identify areas of metastasis or the presence of polyps and assist with staging. A colonoscopy is generally done once an area of concern is identified. ● PET scan : This can provide a more detailed assessment of the stage and location of cancers and is increasingly used in the diagnostic process. A fusion PET–CT scan can be especially helpful and is a newer approach that allows for better visualization of metastatic deposits. ● High-sensitivity fecal occult blood and stool DNA tests : Chemicals or antibodies are used to determine the presence of blood or cancer cell DNA in stool. Although not diagnostic for colorectal cancer on their own, they can aid in choosing diagnostic tools and treatment. ● Blood tests : General assessment of the patient’s overall nutritional, liver, renal, and hemodynamic status is typically done using blood tests. In addition, a serum carcinoembryonic antigen (CEA) level can be drawn. This protein is often present in higher
levels in the blood of those with certain types of cancers. It helps assess if cancer is present and if cancer treatment is effective.
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