Cancer incidence and stage at diagnosis in children and adolescents in the Community of Madrid, 2015-2018.

Background: Cancer is the leading cause of death in children aged 1-14 and the second in 15-19-year-old adolescents in Spain. The Paediatric Population-Based Cancer Registry of the Community of Madrid was created to monitor its incidence and survival.

Objectives: This study presents the incidence of childhood and adolescent cancer (0-19 years) in Madrid at a population level by sex, age group, type of tumour and stage at diagnosis.

Methods: This study was a retrospective analysis of the total number of cases registered in the Paediatric Population-Based Cancer Registry of the Community of Madrid. The registry employs passive and active case finding: by cross-referencing hospital discharge data, primary healthcare data, mortality data and administrative information; and by validation of all potential incident cases through a review of electronic medical charts. All new diagnoses of malignant neoplasms, non-malignant neoplasms of the Central Nervous System, and uncertain and in situ neoplasms of the bladder, identified in 2015-2018 in individuals under age 20 residing in Madrid, were included. Patient information was collected along with tumour characteristics, including stage at diagnosis according to the Toronto Childhood Cancer Stage Guidelines. Age-specific and age-standardised incidence rates were computed with 95% confidence intervals (CI).

Results: A total of 1002 tumours were registered in 5,269,524 person-years, yielding an age-standardised rate of 192.7 (95% CI 184.3, 201.4) cases per million person-years. Male/female rate ratio was 1.1. The most common cancers across all ages comprised CNS tumours, leukaemias and lymphomas (primarily Hodgkin): 45.5 (95% CI 39.9, 51.7), 41.1 (95% CI 35.7, 47.1) and 35.8 (95% CI 30.9, 41.3) cases per million person-years, respectively. The proportion of metastatic tumours at diagnosis was similar for ages 0-14 (18.6%) and 15-19 (18.7%).

Conclusions: This study provides a comprehensive understanding of childhood and adolescent cancer incidence in Madrid. The registry provides high-quality data and consolidates epidemiological surveillance of cancer in the region.