Maja Pohar Perme1, Berta Jereb. 1. Institute of Biomedical Informatics, University of Ljubljana, Ljubljana, Slovenia. maja.pohar@mf.uni-lj.si
Abstract
OBJECTIVES: To evaluate childhood cancer survival in Slovenia, to provide results comparable to ACCIS studies, and to study the effect of recorded variables on 5-year survival. METHODS: The data are registry-based and present a unique collection in terms of control and homogeneity. Survival was explored using Kaplan-Meier estimates and the Cox model. Restricted cubic splines were used to illustrate the nonlinearity of the age and year of diagnosis effect for the four chosen diagnoses. RESULTS: The data set includes 1827 children examined from 1957 to 2002 with the follow-up ending 2007. The overall 5-year survival increased from 0.26 (95%CI [0.21, 0.33]) before 1973 to 0.8 (95% CI [0.74, 0.85]) for patients diagnosed in the period 1998-2002. It is best for Hodgkin disease and leukemia; for non-Hodgkin lymphoma (NHL) and intracranial and intraspinal neoplasms (CNS) the rate of improvement has been slowing down since 1990. Survival is significantly associated with age at diagnosis for patients with leukemia, CNS, NHL, and neuroblastoma (p < .001), the association varies between diseases. Hazard decreases with age for children with CNS and NHL, increases for children with neuroblastoma, and is quadratic with its lowest point at the age of about 5 years for children with leukemia. CONCLUSIONS: The survival experience in Slovenia compares well with those of large samples in the United States SEER program 1975-1995 and the data collected by ACCIS from 62 population-based cancer registries in Europe. The hazard of dying has been decreasing constantly, mainly due to improvements in leukemia treatment.
OBJECTIVES: To evaluate childhood cancer survival in Slovenia, to provide results comparable to ACCIS studies, and to study the effect of recorded variables on 5-year survival. METHODS: The data are registry-based and present a unique collection in terms of control and homogeneity. Survival was explored using Kaplan-Meier estimates and the Cox model. Restricted cubic splines were used to illustrate the nonlinearity of the age and year of diagnosis effect for the four chosen diagnoses. RESULTS: The data set includes 1827 children examined from 1957 to 2002 with the follow-up ending 2007. The overall 5-year survival increased from 0.26 (95%CI [0.21, 0.33]) before 1973 to 0.8 (95% CI [0.74, 0.85]) for patients diagnosed in the period 1998-2002. It is best for Hodgkin disease and leukemia; for non-Hodgkin lymphoma (NHL) and intracranial and intraspinal neoplasms (CNS) the rate of improvement has been slowing down since 1990. Survival is significantly associated with age at diagnosis for patients with leukemia, CNS, NHL, and neuroblastoma (p < .001), the association varies between diseases. Hazard decreases with age for children with CNS and NHL, increases for children with neuroblastoma, and is quadratic with its lowest point at the age of about 5 years for children with leukemia. CONCLUSIONS: The survival experience in Slovenia compares well with those of large samples in the United States SEER program 1975-1995 and the data collected by ACCIS from 62 population-based cancer registries in Europe. The hazard of dying has been decreasing constantly, mainly due to improvements in leukemia treatment.