The overall completeness of the SCR is high and comparable to other high quality registers in Northern Europe. For most uses in epidemiological or public health surveillance, the underreporting will be without major impact. However, for specific research questions our findings have implications, as the degree of underreporting is site specific, increases with age, and does not seem to be random, as diagnoses without histology or cytology verification are overrepresented. An annual comparison of the SCR against the HDR could point to hospitals, geographic areas or specific diagnoses where organizational and administrative changes should be introduced to improve reporting.

The theory that cancer may arise under conditions of reduced immune capacity is supported by observations of humans with immune deficiencies such as occur following organ transplants. However, no study on humans has been done in which the reference population was the same as that in which the cancer cases arose and in which there was a sufficiently long period of follow-up. Information on 5,692 Nordic recipients of renal transplants in 1964-1982 was linked with the national cancer registries (1964-1986) and population registries. Person-years at risk were calculated from the date of first transplantation until death or the end of the study period and were multiplied by the appropriate age- and calender-specific incidence rates to obtain the expected numbers of cancers. Standardized incidence ratios (SIR) were calculated after stratification by a number of recorded variables. Altogether, 32,392 person-years were accrued, and 471 cancers occurred, yielding overall SIR of 4.6 (95% CI, 4.0 to 5.2) for males and 4.5 (95% CI, 4.0 to 5.2) for females. Significant overall 2- to 5-fold excess risks in both sexes were seen for cancers of the colon, larynx, lung and bladder, and in men also for cancers of the prostate and testis. Notably high risks, 10-fold to 30-fold above expectation, were associated with cancers of the lip, skin (non-melanoma), kidney and endocrine glands, also with non-Hodgkin's lymphoma, and in women also with cancers of the cervix and vulva-vagina. Among a number of donor and recipient variables studied, including tissue types and compatibility (ABO, HLA, DR), age below 45 years at the time of transplantation was the most important determinant for increased risk at most sites. Kidney transplantation increases the risk of cancer in the short and in the long term, consistent with the theory that an impaired immune system allows carcinogenic factors to act. The tumor risk is small in comparison with the benefits of transplants, but patients should be followed up for signs of cancer.

PURPOSE: To assess the risk of death in patients who survive more than 5 years after diagnosis of childhood cancer and to evaluate causes of death in fatal cases. PATIENTS AND METHODS: This was a population-based study in the five Nordic countries (Denmark, Finland, Iceland, Norway, and Sweden) using data of the nationwide cancer registries and the cause-of-death registries. The study cohort included 13,711 patients who were diagnosed with cancer before the age of 20 years between 1960 and 1989 and who survived at least 5 years from diagnosis. By December 31, 1995, 1,422 patients had died, and death certificates were assessed in 1,402. Standardized mortality ratios (SMRs) for validated causes of death were calculated based on 156,046 patient-years at risk. RESULTS: The overall SMR was 10.8 (95% confidence interval [CI], 10.3 to 11.5), mainly due to high excess mortality from the primary cancer. SMR for second cancer was 4.9 (95% CI, 3.9 to 5.9) and was 3.1 (95% CI, 2.8 to 3.5) for noncancer death. The pattern of causes of death varied markedly between different groups of primary cancer diagnoses and was highly dependent on time passed since diagnosis. Overall late mortality was significantly lower in patients treated during the most recent period of time, 1980 to 1989, compared with those treated from 1960 to 1979 (hazard ratio, 0.61; 95% CI, 0.54 to 0.70), and there was no increase in rates of death due to cancer treatment. CONCLUSION: Long-term survivors of childhood cancer had an increased mortality rate, mainly dying from primary cancers. However, modern treatments have reduced late cancer mortality without increasing the rate of therapy-related deaths.