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A cohort of 5072 patients with pernicious anaemia was identified in the Danish Hospital Discharge Register from 1977 to 1989 and, through linkage to the Danish Cancer Registry, the occurrence of cancer in the cohort was determined up to 1991. Observed numbers of cancer cases during 1-15 years of follow-up were compared with expected numbers based on national incidence rates. Besides the well-established increased risk for stomach cancer, the analysis also revealed a 2-fold increase in the relative risk for cancer of the buccal cavity and pharynx among pernicious anaemia patients in accordance with previous studies; previously reported elevated risks for other digestive tract cancers were not confirmed. There was a non-significantly increased risk for lymphatic and haematological malignancy but the risk tended to disappear after 5 years of follow-up, indicating a possible selection bias. Decreased risks for cervical cancer and non-melanoma skin cancer were also seen.

Removal of the spleen may possibly affect functions of the immune system. Cancer risk following splenectomy was evaluated by performing a linked register study in Denmark from 1977-89. From the Hospital Discharge Register we identified 1103 patients splenectomized after traumatic rupture of the spleen and 5212 patients splenectomized for various malignant or non-malignant disorders and both groups were followed for cancer occurrence in the Danish Cancer Registry. No increased risk for cancer was observed among patients who underwent splenectomy due to trauma. In contrast, there were excesses of a number of specific cancers among patients who underwent splenectomy for non-traumatic reasons, but to a large extent this could be explained by factors related to the underlying disease and/or treatment of the disease.

A cohort of 5,546 ulcerative colitis patients was identified from the Danish Hospital Discharge Register for 1977-1989. Patients not included in the cohort comprised those with proctitis, those treated in outpatient clinics and those for whom follow-up was less than 1 year. The cohort was linked to the Danish Cancer Registry in order to assess the risks for colorectal and other cancers. The linkage revealed a significant increase in the number of colorectal cancers over that in the general population (RR = 1.8; n = 42; 95% CI = 1.3-2.4) with consistent relative risks during early and late follow-up. The relative risk was considerably higher among younger (20-39 years: RR = 22; n = 8; 95% CI = 9.7-44) than older patients (> or = 60 years: RR = 1.3; n = 25; 95% CI = 0.8-1.9), but the risk difference between patients and the general population was approximately constant across all ages. In addition, we observed a significant increase in the relative risk of hepatobiliary cancers (RR = 2.3; n = 9; 95% = 1.0-4.3) and a slight but significant increase in the relative risk of non-melanoma skin cancer (RR = 1.4; n = 37; 95% CI = 1.0-1.9). In summary, our population-based study confirms the increased risk of colorectal cancer among patients with ulcerative colitis and provides new leads suggesting that hepatobiliary cancer and non-melanoma skin cancer should be considered as possible sites for future patient monitoring.

Polymyositis and dermatomyositis (PM/DM) have been associated with cancer, although the long-term risks are poorly understood. To evaluate the risk of cancer by time periods subsequent to PM/DM diagnosis, a cohort of 539 patients hospitalized with PM/DM in Denmark between 1977 and 1989 was identified from the Danish Central Hospital Discharge Register. Cancer incidence among cohort members was ascertained by linkage to the Danish Cancer Registry using a unique personal-identification number. The overall cancer risk was elevated significantly among patients with DM (standardized incidence ratio [SIR] = 3.8, 95 percent confidence interval [CI] = 2.6-5.4) and to a lesser extent PM (SIR = 1.7, CI = 1.1-2.4). Significant excesses were observed for cancers of lung, ovary, and lymphatic and hematopoietic system. However, the excess cancer incidence declined steadily with increasing years since initial diagnosis of PM/DM. The cancer risk was increased about sixfold (SIR = 5.9, CI = 3.8-8.7) during the first year, but was lower during the second year (SIR = 2.5, CI = 1.1-4.8), with no significant excesses in subsequent years of follow-up. These findings confirm that PM/DM may occur as a paraneoplastic syndrome that calls for steps aimed at early cancer detection and treatment. Among long-term survivors of PM/DM, however, there is little evidence to warrant extensive preventive and screening measures beyond those recommended for the general population.