Progress against childhood and adolescent acute lymphoblastic leukaemia in the Netherlands, 1990-2015

Abstract

We assessed the epidemiologic progress against childhood and adolescent acute lymphoblastic leukaemia (ALL) in the Netherlands over a 26 year period. ALL patients <18 years were selected from the Netherlands Cancer Registry and the Dutch Childhood Oncology Group. Trend analyses were performed over time and by age group and ALL subtype. Between 1990 and 2015, 2997 ALL patients were diagnosed, i.e. 115 patients (range 87-147) per year. Overall incidence remained stable at 37 per million children, despite increases for B-cell precursor ALL (BCP-ALL) at age 10-14 years (AAPC + 1.4%, p = 0.04) and T-cell ALL at 15-17 years (AAPC + 3.7%, p = 0.01). Five-year survival increased from 80% in 1990-94 to 91% in 2010-15 (p < 0.01). Mortality decreased by 4% annually (p < 0.01). Patients 15-17 years were increasingly treated in a paediatric oncology centre, from 35% in 1990-94 to 87% in 2010-15 and experienced a 70% reduction of risk of death compared to those treated outside such a centre (p < 0.01). Significant progress against childhood ALL has been made in the Netherlands, visible by improved survival rates coinciding with declining mortality rates. These outcomes were accompanied by stable incidence rates, despite increases for BCP-ALL at age 10-14 years and T-cell ALL at age 15-17 years.

Fig. 1. Time trends in incidence of patients aged <18 years with ALL by age groups in the Netherlands, 1990–2015.

Three-year moving averages of the age-standardised incidence rate of ALL (standardised according to the World Standard Rate, WSR) and age-specific incidence rates are shown. The average annual percentage change (AAPC) was estimated for each year of diagnosis with linear regression analyses.

Fig. 2. Time trends in overall survival of patients aged <18 years with ALL in the Netherlands, 1990–2015.

The 1-year overall survival did not improve over time, p = 0.70. The 5- and 10-year overall survival did improve over time, both p < 0.01. The p for trend was tested with streg and adjusted for follow-up time.

Fig. 3. Time trends in overall survival of patients aged <18 years with ALL by age groups in the Netherlands, 1990–2015.

Five (a) and 10-year (b) overall survival with corresponding confidence intervals, corrected for follow-up time. Ten-year overall survival for infants, patients aged <0 years is not given due to <20 patients in this group. And for patients diagnosed in the last period, follow-up time is not sufficient to report 10-year survival. * Indicates significant improvement of survival over time for that age group, p ≥ 0.01 and p < 0.05 ** Indicates significant improvement of survival over time for that age group, p < 0.01 P for trend adjusted for follow-up time.

Fig. 4. Proportion of patients with ALL treated at a paediatric oncology centre by age groups, 1990–2015.

Age groups are displayed in dark gray as age <15 years and light gray age 15–17 years, respectively.