ADENOCARCINOMA OF THE APPENDIX

Abstract

Primary adenocarcinoma of the appendix is a rare, seldom diagnosed neoplasm, even as incidental finding during appendectomy. Relatively little is known about its pathology and management. It is found in approximately 0.1% of appendectomies, with an incidence rate of 0.2 per 100, 000 people per year. The mean age at presentation is around 60 years old and males are affected 1.5 times more frequently than females. It presents as either a colonic type tumor, which is poorly differentiated and more aggressive, or as a mucinous type, which may show abundant extra-cellular mucin and is well differentiated. Clinically, it usually presents as acute appendicitis or as an abdominal mass. It is often associated with other synchronous malignancies, such as colonic or ovarian lesions, as well as a higher incidence of metachronous tumors, creating a need for lifelong follow-up after treatment. Right hemicolectomy is the preferred treatment for both colonic and mucinous type lesions. Some studies still suggest that an appendectomy is sufficient if the tumor is confined to the mucosa or if no residual tumor is found in the colon in the mucinous type. However, the high rate of perforations argues against this approach. For the mucinous type of cancer, bilateral oophorectomy, especially if the patient is post-menopausal, is sometimes advised. Post-operative chemotherapy, with or without radiotherapy, may improve the morbidity and mortality rates of pseudomyxoma peritonei. The prognosis, as in colonic tumors, is defined by stage and histology. The overall 5-year survival rates are 71% for the mucinous type and 41% for the colonic type, and 100%, 67%, 50%, and 6% for stages A, B, C, and D, respectively, or 68%, 51%, and 7% for grades I, II, and III respectively.