A substantial excess risk of lymphomas and nonmelanoma skin cancer has been demonstrated following organ transplantation. Large sample size and long follow-up time may, however, allow more accurate risk estimates and detailed understanding of long-term cancer risk. The objective of the study was to assess the risk of cancer following organ transplantation. A nationwide cohort study comprising 5931 patients who underwent transplantation of kidney, liver or other organs during 1970 -1997 in Sweden was conducted. Complete follow-up was accomplished through linkage to nationwide databases. We used comparisons with the entire Swedish population to calculate standardised incidence ratios (SIRs), and Poisson regression for multivariate internal analyses of relative risks (RRs) with 95% confidence intervals (CI). Overall, we observed 692 incident first cancers vs 171 expected (SIR 4.0; 95% CI 3.7 -4.4). We confirmed marked excesses of nonmelanoma skin cancer (SIR 56.2; 95% CI 49.8 -63.2), lip cancer (SIR 53.3; 95% CI 38.0 -72.5) and of non-Hodgkin's lymphoma (NHL) (SIR 6.0; 95% CI 4.4 -8.0). Compared with patients who underwent kidney transplantation, those who received other organs were at substantially higher risk of NHL (RR 8.4; 95% CI 4.3 -16). Besides, we found, significantly, about 20-fold excess risk of cancer of the vulva and vagina, 10-fold of anal cancer, and five-fold of oral cavity and kidney cancer, as well as two-to four-fold excesses of cancer in the oesophagus, stomach, large bowel, urinary bladder, lung and thyroid gland. In conclusion, organ transplantation entails a persistent, about four-fold increased overall cancer risk. The complex pattern of excess risk at many sites challenges current understanding of oncogenic infections that might become activated by immunologic alterations.

Perioperative smoking cessation seems to be an effective tool to reduce postoperative complications even if it is introduced as late as 4 weeks before surgery.

Objective-To investigate a possible link between exposure to ultraviolet light and the almost epidemic increase in non-Hodgkin's lymphoma worldwide. Because ultraviolet light is known to cause skin cancers, the association between non-Hodgkin's lymphoma and skin cancer was studied.Design-Secondary occurrence of either malignant melanoma or squamous cell skin cancer in cohorts of patients with a first diagnosis of either non-Hodgkin's lymphoma or chronic lymphocytic leukaemia, and vice versa, were studied. Expected numbers of subsequent cancers were calculated by sex, age, and period specific national incidence rates multiplied by the person years under observation in the cohorts. Setting-Denmark (1943-89) and Sweden (1958-89).Subjects-Four population based cohorts identified in the nationwide cancer registries (34641 people with non-Hodgkin's lymphoma, 17400 with chronic lymphocytic leukaemia, 34989 with malignant melanoma, 25 980 with squamous cell skin cancer). A total of 562 085 person years were accrued for the analysis.Main outcome measures-The ratios of observed to expected cancers (the standardised incidence ratio) served as a measure ofthe relative risk.Results-The relative risk for developing squamous cell skin cancer was 5 5 (95% confidence interval 4*6 to 6 6) among patients with non-

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A history of high UV exposure was associated with reduced risk of non-Hodgkin lymphoma. The positive association between skin cancer and malignant lymphomas is, therefore, unlikely to be mediated by UV exposure.