Abstract
BackgroundSmall intestinal cancer is less common than some other gastrointestinal malignancies. Tumours of different histological types and anatomical sites of origin have therefore often been described together. The aim of this study was to investigate the epidemiology for each of the four main subtypes: duodenal adenocarcinoma (D-AC), duodenal neuroendocrine tumour (D-NET), jejunoileal adenocarcinoma (J/I-AC), and jejunoileal neuroendocrine tumour (J/I-NET).MethodsAll patients with small intestinal cancer diagnosed between 1960 and 2015 were identified from the Swedish Cancer Register. The age-adjusted incidence rate with incidence rate ratios, as well as overall (OS) and net (NS) survival, were determined and temporal trends were analysed.ResultsThe incidence rate was highest for J/I-NET, with 9.98 clinical diagnoses per million in 2010–2015. Clinical diagnosis of D-AC increased more than 10-fold and surpassed J/I-AC as the second most common subtype. D-NET was by far the least common subtype. Diagnosis at autopsy became less common over time, whereas clinical diagnoses increased significantly for all four subtypes. All subtypes except J/I-AC affected men more often than women. The age distribution was similar between subtypes, although patients with adenocarcinomas were slightly older. Survival was generally much better for patients with NET than for those with adenocarcinoma. Both OS and NS showed a negative association with advancing age. Survival improved only for J/I-NET from a 5-year NS of 0.69 in the 1960s to 0.81 in 2010–2015.ConclusionThe incidence of small intestinal cancer is increasing, particularly for D-AC and in the elderly. Survival of patients with small intestinal cancer has improved only for J/I-NET over the last decades.
Highlights
The incidence rate was highest for jejunoileal neuroendocrine tumour (J/I-neuroendocrine tumour (NET)), with 9.98 clinical diagnoses per million in 2010–2015
duodenal neuroendocrine tumour (D-NET) was by far the least common subtype
DNETs were more common in men than in women, and virtually nonexistent before the age of 40 years, the incidence increased with age (Fig. 2)
Summary
Small intestinal cancer represents less than 2.5 per cent of all gastrointestinal cancer. Most previous epidemiological studies grouped tumours of different histological types and/or anatomical sites of origin. This is inappropriate as adenocarcinoma and NET have distinctly different tumour biology, treatment and prognosis. Small intestinal cancer is less common than some other gastrointestinal malignancies. Diagnosis at autopsy became less common over time, whereas clinical diagnoses increased significantly for all four subtypes. Survival was generally much better for patients with NET than for those with adenocarcinoma. Both OS and NS showed a negative association with advancing age. Survival of patients with small intestinal cancer has improved only for J/I-NET over the last decades
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