Spatiotemporal variations in childhood lymphoma cancer incidence and its survival rate in Iran, 2005-2015: a cross-sectional study.

Background: Childhood lymphoma is the second leading cause of cancer in children under 15 years of age in Iran. The aim of this study was to investigate the spatial and time variations in lymphoma incidence as well as the children's survival time in Iran.

Method: This cross-sectional study was conducted using lymphoma cases (children under 14 years of age) from 2005 to 2015, and the data were obtained from the National Cancer Registry Center. The frequency, age-standardised incidence rate (ASIR), spatial clustering in national level and the survival rate (1 year and 5 years) using Kaplan-Meier method were evaluated. We used Spatial and Temporal Scan statistics software in order to detect statistically significant clusters in spatial analysis.

Results: A total number of 746 girls and 1610 boys were diagnosed with lymphoma during a 10-year period. ASIRs (per 100 000 people) for girls ranged from 0 in Ilam to 3.47 in Yasuj, and it ranged from 0.19 in Ilam to 5.91 in Yazd for boys from 2005 to 2015. Spatial analysis result showed a large statistically significant cluster (the most likely cluster) for both boys (relative risk (RR)=2.37) and girls (RR=2.49) located in the northwest of Iran. Fortunately, survival rate for both boys and girls was over 95.5%.

Conclusion: Lymphoma incidence rates had heterogeneous geographical distribution, and some significant clusters were identified which strengthens the role of possible aetiological factors, and further studies are needed to clarify this ambiguity. Fortunately, the survival rate of this cancer in Iran was good and it was similar to the high-income countries.