Cancer outcome among adolescents in Canada.

10024 Background: Adolescents and young adults (AYA) with cancer, commonly defined as patients aged 15–39 years at diagnosis, experience higher morbidity and mortality compared with other age groups. In this study, we compared outcomes of adolescents with newly diagnosed cancer treated at Canadian pediatric oncology centers with those of younger children. Methods: We conducted a retrospective cohort study using the population-based CYP-C database, including children aged 1–18 years with newly diagnosed cancer across Canada (2015–2020). Event-free survival (EFS) and overall survival (OS) were compared between adolescents (15–18 years) and younger children (1 to <15 years) across cancer subtypes using Kaplan–Meier analyses and univariable and multivariable Cox proportional hazards models. Results: Of the 6,794 patients, adolescents aged 15–18 years comprised 16% (n=1,075) of the cohort. Median age at diagnosis was 16 years (IQR: 15.7–17.2), and among those with solid tumors, 26% (n=150) had metastatic disease at diagnosis. The most frequent adolescent cancers were Hodgkin lymphoma (20%), gliomas and other glioneuronal tumors (12%), acute lymphoblastic leukemia (11%), osteosarcoma (6%), thyroid carcinoma (6%), malignant extracranial germ cell tumors (5%), and Ewing sarcoma (4%). Adolescents with leukemia had comparable 5-year EFS (71% vs. 79%; p=0.06) and OS (83% vs. 89%; p=0.07) to younger children, as did those with non-central nervous system (CNS) solid tumors for EFS (65% vs. 65%; p=0.55) and OS (74% vs. 75%; p=0.23). Among patients with sarcomas, adolescents had similar 5-year EFS (50.7% vs. 52.0%, p=0.55) and OS (55.6 vs. 59.7%, p=0.14) to younger children. Adolescents with CNS tumors had superior EFS (83% vs. 66%; p=0.005) and OS (89% vs. 73%; p=0.006), primarily driven by ependymoma and choroid plexus tumors, and other gliomas/glioneuronal tumors excluding pilocytic astrocytoma. Conclusions: Although AYA with cancer are often reported to have poorer outcomes, adolescents aged 15–18 years treated exclusively in Canadian pediatric oncology centers did not have inferior outcomes to younger children, underscoring the effectiveness of pediatric treatment approaches. 5-year EFS and 5-year OS of adolescents (≥15 years-old) vs. younger children (1 to < 15 years old) across major cancer categories. - Adolescents 5-year EFS (%) [95% CI] Younger children 5-year EFS (%) [95% CI] p-value Adolescents 5-year OS (%) [95% CI] Younger children 5-year OS (%) [95% CI] p-value All cancers 76.4 [72.8-79.9] 72.6 [70.8-74.3] 0.12 84.7 [81.4-87.4] 81.1 [79.6-82.7] 0.13 Leukemias 71.2 [58.7-80.5] 79.0 [75.8-81.9] 0.06 83.2 [73.3-89.7] 88.6 [86.2-90.6] 0.07 Lymphomas 88.5 [82.6-92.5] 87.3 [82.6-90.7] 0.63 96.2 [91.9-98.3] 95.5 [92.7-97.3] 0.50 Non-CNS solid tumors 65.4 [58.6-71.3] 65.2 [61.8-68.3] 0.55 73.5 [66.7-79.0] 74.8 [71.5-77.9] 0.23 CNS tumors 83.1 [74.2-89.1] 66.3 [62.5-69.8] 0.005 89.1 [82.0-93.5] 72.5 [68.8-75.9] 0.006