Cancer following cardiac catheterization in childhood

Abstract

Background: Low-dose ionizing radiation is one of the definitive risk factors for cancer development. Nevertheless, only a few follow-up studies of children subjected to cardiac catheterization have been performed, yielding inconsistent results.

Methods: Our study group included 674 children who underwent cardiac catheterization due to congenital anomalies, between the years 1950-1970 in three major medical centres in Israel. A registered nurse conducted a review of the children's medical files in each hospital. Demographic data and vital status were ascertained from the Israeli National Registry, using a unique identity number. Subsequently, the study cohort was linked with the Israeli National Cancer Registry, in order to identify cancer cases that had been diagnosed through December 1996, the last follow-up date of the study.

Results: Over 75% of the study participants were native-born; 56.2% were males. Approximately 78% of the cohort subjects were alive at the end of follow-up; 28.6% of the participants underwent more than one procedure. All of the diagnosed cases occurred in males. Expected number of malignancies for all sites was 4.75, while the observed number was 11.0 (standardized incidence ratio [SIR] = 2. 3; 95% CI : 1.2-4.1). Of the 11 cancer cases, 4 lymphomas were observed (0.63 were expected, SIR = 6.3; 95% CI : 1.7-16.2). One of these was Hodgkin's Disease. There were also three cases of melanoma as opposed to 0.62 expected (SIR = 4.9; 95% CI : 1.0-14.2).

Conclusions: This finding is compatible with current knowledge about the carcinogenic effect of low-dose irradiation but differs in the occurrence of an excess of lymphoma in the absence of an excess of leukaemia, which has not been reported before. The dissonance between males and females is yet to be resolved.

Implications: Radiation doses that are used currently during cardiac catheterization are lower than in the past. Yet, the procedure is more common and frequently involves longer duration due to therapeutic interventions. The possible long-term results of such an exposure should be kept in mind.