Appendix cancer overview
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Soroush Seifirad, M.D.[2]
Overview
Historical Perspective
Appendix cancer was first described in the published literature by Sir George Thos. Beatson, an English surgeon, in 1913.[1]Development of surgical sciences revolutionized cancer care, appendix cancer was not an exception. Introduction of chemotherapy agents such as 5-fluorouracil (5-FU) Irinotecan, Oxaliplatin, Vascular endothelial growth factor receptor inhibitors (bevacizumab), Epidermal growth factor receptor inhibitors (cetuximab and panitumumab), Aflibercept, Regorafenib: inhibitor of angiogenic tyrosine kinases (including the VEGF receptors 1,2, and 3), Capecitabine as well as introduction of intraperitoneal chemotherapy including hyperthermic intraperitoneal chemotherapyadvanced appendix cancer treatment. Development of new Imaging modalities such as CT scan, MRI as well as specific imaging modalities such as Somatostatin scintigraphy also transfigured approaching to the patients with appendix cancer. Genetic studies introduced novel horizons in approaching patients with appendix cancer.
Classification
Appendix cancer is classified according to the histological findings. According to WHO classification there are four major groups of appendix cancer including epithelial tumors, non-epithelial tumors, secondary tumors, and hyperplastic (metaplastic) polyps.[2] Carcinoid (well differentiated endocrine neoplasm), and adenocarcinoma are two major subtypes of epithelial tumors, making the majority of appendix cancer cases.
Pathophysiology
The pathophysiology of appendix cancer depends on the histological subtype. There are two major subtypes of appendix cancer, adenocarcinomae and carcionid tumors. While carcinoid tumors arises from enterochromaffin cells (Kulchitsky cells), which are secretory cells that are normally involved in neuroendocrine hormonal secretions, adenocarcinomae are the result of mutations in mucous producing epithelial cells. Their physiology, pathophysiology, genetic pathways, prognosis as well as epidemiology are different and hence discussed separately. The progression to adenocarcinoma usually involves the KRAS, APC, TP53, and RAF pathways, While β-catenin, NF1, and MEN1 genes are major contributors of carcinoid tumor s progression.
Causes
Appendix cancer is a quit rare disorder. To study causality, cohort studies are needed. Because of very low incidence of appendiceal cancers, no cohort study was conducted to study casualty, and hence there are no established cause for appendix cancer. To review risk factors for the development of appendiceal cancers, click here.
Differentiating Appendix cancer from Other Diseases
Epidemiology and Demographics
Risk Factors
Alike other malignancies, common risk factors in the development of appendix cancer are a combination of environmental and genetic factors. Common risk factors in the development of appendix cancer include age, sex, smoking, familial cancer disorders such as MEN1 Syndrome and HNPCC, as well as long standing chronic inflammatory disorders such as ulcerative colitis and Crohn's disease.[3][4][5]
Screening
- There is insufficient evidence to recommend routine screening for appendiceal cancers. Meanwhile patients with certain conditions like familial cancer syndromes as well as patients with long standing chronic inflammatory disease like ulcerative colitis might drive a benefit from appropriate GI screenings according to the specific guidelines for their specific conditions.[3]
Natural History, Complications, and Prognosis
Because of the location and size of appendix most of the patients with appendix cancer may be initially asymptomatic. Early clinical features might include periodical unspecific abdominal pain, bloating, and nausea. Most of appendix cancer cases are discovered after surgical or histological evaluation of a patient with acute appendicitis, or are an accidental finding in imaging studies for the other reasons. Around one percent of all appendectomy specimens are malignant. Appendix cancer account for 0.5 percent of all intestinal neoplasms. If left untreated, the majority of patients with appendix cancer may progress to develop peritoneal carcinomatosis and metastases. Prognosis is generally excellent and good in carcinoid tumors and adenocarcinomae respectively. Prognostic factors including tumor stage, tumor size, histologic as well genetic characteristics of appendiceal tumors were discussed in details.
Diagnosis
Diagnostic Study of Choice
History and Symptoms
Physical Examination
Laboratory Findings
Electrocardiogram
X-ray
Echocardiography and Ultrasound
CT scan
MRI
Other Imaging Findings
Other Diagnostic Studies
Treatment
Medical Therapy
Interventions
Surgery
Primary Prevention
Secondary Prevention
References
- ↑ Beatson GT (1913) Note on a Case of Carcinoma of the Vermiform Appendix in a Girl, Aged 20 Years. Glasgow Med J 80 (6):418-422. PMID: 30435413
- ↑ Chapter 5: Tumours of the Appendix - IARC. https://www.iarc.fr/en/publications/pdfs-online/pat-gen/bb2/bb2-chap5.pdf Accessed on January 15, 2019
- ↑ 3.0 3.1 Odze RD, Medline P, Cohen Z (1994). "Adenocarcinoma arising in an appendix involved with chronic ulcerative colitis". Am J Gastroenterol. 89 (10): 1905–7. PMID 7942699.
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