Risk of second primary malignancies and causes of death in patients with adenocarcinoma and carcinoid of the small intestine.

We studied risk of second malignancies and causes of death in 1829 cases of adenocarcinoma and 3055 cases of carcinoid tumours in the small bowel reported to the Swedish Cancer Registry from 1960 through to 2000. Data on causes of death were analysed as from 1966 whereas data on second tumours was available during the whole registry-period. Follow-up was available until 2001. Standard mortality ratio (SMR) and standard incidence ratio (SIR) were calculated. Female patients with adenocarcinoma had increased risk of acquiring cancer in the female genital organs (SIR 3.2; 95% confidence intervals (CI) 1.9-5.0) and breasts (SIR 2.7; 95% CI 1.1-5.4). Both sexes combined had increased risk of second tumours in the gastrointestinal tract (SIR 1.5; 95% CI 1.1-2.1) and skin (SIR 4.6; 95% CI 1.2-12). Men with carcinoid tumour had increased risk of prostate cancer (SIR 2.8; 95% CI 1.6-4.6). Increased risk was seen for both sexes with carcinoid for malignant melanoma (SIR 6.3; 95% CI 2.7-12), malignant skin tumours (SIR 3.6; 95% CI 1.7-6.7) and malignancies of endocrine organs (SIR 2.3 95% CI 1.3-3.8). Patients with adenocarcinoma had increased risk of dying from malignant diseases other than the primary cancer (SMR 9.5; 95% CI 8.6-10) and gastrointestinal disease (SMR 2.6 95% CI 1.6-4.2). The cohort with carcinoid had higher than expected risk of dying from malignant disease (SMR 4.3; 95% CI 4.0-4.6), gastrointestinal disease (SMR 2.8; 95% CI 2.1-3.6) and cardiovascular disease (SMR 1.1; 95% CI 1.0-1.3). The increased risk of second malignant tumours is an indication of common aetiology, or possibly, a general vulnerability to malignant disease for these patients. A detailed analysis of causes of death in a population-based cohort of small intestinal malignancies has not been presented before in the literature.