# Cancer Burden in Adolescents and Young Adults in Belgium: Trends to Incidence Stabilisation in Recent Years with Improved Survival

## TL;DR

This study examines cancer trends in adolescents and young adults in Belgium from 2004 to 2020, finding that while cancer incidence stabilized after 2015, survival rates improved, though some cancers still have lower survival compared to other age groups.

## Contribution

The study provides a detailed epidemiological analysis of cancer trends in adolescents and young adults in Belgium, highlighting survival improvements and incidence stabilization.

## Key findings

- Cancer incidence stabilized after 2015 except for specific cancers like Hodgkin lymphoma and testicular cancer.
- Five-year relative survival exceeds 80% overall but remains lower for certain cancers compared to children or older adults.
- Belgian trends align with neighboring countries like the Netherlands, France, and Germany.

## Abstract

While the cancer burden in adolescents and young adults (AYA) is increasing, cancer is the fourth leading cause of death among AYA globally. AYA represent a distinct patient population that is often overlooked in favour of paediatric and older adult patients. It is therefore crucial to better understand AYA cancers. This study aims to provide an overview of the specific epidemiological trends of AYA (15–39 years) cancer patients in Belgium over the period 2004–2020 by age sub-groups and by placing these trends in an international context. The increased cancer burden is mostly due to improved survival, while incidence is stabilised after 2015. Although varying by cancer type, survival outcomes for AYAs are generally lower than those observed in children with similar malignancies and not systematically better than in the older age group, 40–49 years. These results offer valuable insights to support policymakers in optimizing AYA cancer management in Belgium.

Background/Objectives: This population-based study examined epidemiological trends of primary cancers in adolescents and young adults (AYAs) to enhance the understanding of the specific spectrum of cancers impacting AYAs in Belgium. Methods: Data on incidence, prevalence, mortality, and survival were obtained from the Belgian Cancer Registry (2004–2020, N = 43,535). (A)APC statistics were compared with children (5–14 years) and adults (40–49 years). Results: Cancer incidence increased by 0.4% annually from 66 to 80 per 100,000 person-years (ESR2013) but stabilised after 2015, except for Hodgkin lymphoma, chronic myeloid neoplasms, and testicular and breast cancer, which continued to rise. Mortality decreased by 1% annually, from 10 to 7 per 100,000 person-years (2004–2019). Five-year relative survival (RS) was 87% but remained low for certain cancers, including ovary (78%), central nervous system (67%), precursor haematopoietic neoplasms (64%), gastrointestinal (excl. colorectal) (49%), and lung-bronchus-trachea cancers (42%). Conclusions: From 2004–2020, the cancer burden among AYAs in Belgium increased due to improved survival, while incidence stabilised after 2015. Five-year RS exceeds 80% overall but remains lower for some cancers compared to children (e.g., precursor haematopoietic neoplasms) or older adults (e.g., breast cancer, sarcoma). The Belgian epidemiological trends align with those in neighbouring countries (Netherlands, France, Germany).