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Duodenal adenocarcinoma
Overview
Duodenal adenocarcinoma (DA) is a rare malignancy that accounts for less than 1% of all gastrointestinal (GI) cancers and occurs at a rate of less than 6 cases per million person years. In 2018 it was estimated that within the United States there were 10,470 cases of small bowel cancer with 1450 deaths. Even though the duodenum comprises a relatively small portion of the small intestine, DA represents the majority of small bowel adenocarcinomas (SBAs), with reported rates ranging between 55% and 82% of cases. With regard to histology, adenocarcinoma accounts for approximately 40% of all small bowel cancers, and it is the most common histologic subtype of malignancy of the duodenum compared with lymphoma, carcinoid, and GI stromal tumors. , Interestingly, epidemiologic studies suggest there may be an increasing incidence of DA. ,
Unfortunately, prognosis for DA remains poor, with 5-year overall survival less than 50%, even with attempted curative surgical resection, and with 5-year survival rates between 15% and 33% when patients at all stages at diagnosis are considered. , , One persistent challenge to advancing treatment for DA is its rarity, which is why many studies include DA alongside analysis of all small bowel cancers or periampullary tumors. In fact, clinical practice guidelines for SBA were only recently published, first by a French intergroup in 2018 and then by the National Comprehensive Cancer Network in 2019. ,
Presentation
DA demonstrates a slight male predominance with the most common presentation during the 6th or 7th decade of life. The clinical presentation of DA may be delayed until the tumor has grown large enough to cause symptoms. The most common symptoms are bleeding or those related to gastric outlet obstruction, such as nausea, vomiting, anorexia, early satiety, and weight loss. Nonspecific or vague abdominal pain is also commonly reported. Additionally, patients may be seen with jaundice if the cancer is in the second portion of the duodenum. A retrospective Japanese study of 205 patients with SBA found that 64 patients (43.0%) with DA were asymptomatic at the time of diagnosis, because 85.9% of asymptomatic cases were found by esophagogastroduodenoscopy (EGD) completed for unrelated reasons. In contrast, 47 patients (83.8%) with jejunoileal adenocarcinoma were symptomatic at the time of diagnosis. This asymptomatic progression of DA leads to high rates of late stage or unresectability at the time of diagnosis, with 24.2% of new DA cases found to be stage 3, and 20.8% found at stage 4 disease in the Japanese cohort study. In Western countries where EGD for gastric cancer surveillance is not routine, the risk for late presentation of DA may be even higher. As a consequence, a significant proportion of DA patients do not proceed to curative intent surgical resection, with a recent systematic review indicating 29% of patients with DA receiving palliative treatment only. Similarly, a recent prospective cohort study from France demonstrated that less than 60% of SBAs were resectable at the time of diagnosis. Periampullary tumors often present earlier than extra ampullary tumors, and perhaps for this reason, a slightly greater percentage of these lesions are resectable at presentation.
Grossly, DAs appear as circumferential “napkin-ring” type masses or as polypoidal fungating masses ( Fig. 63.1 ). Median tumor size at presentation is approximately 4.0 to 4.6 cm. , , However, it is important to note that size may not be a factor in resectability of DA.
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