Symptom burden, quality of life (QoL), social and behavioral characteristics in young patients (<40 years old) with cancer: A prospective cohort of 7323 patients across 110 sites in France and Belgium.

1615 Background: Cancer in individuals under 40 years old is increasingly recognized as a public health concern, characterized by unique etiologies, biology, and clinical behaviors compared to older populations. Young patients may also face specific physical, psychosocial, and socioeconomic challenges that can influence outcomes which are often suboptimally addressed in routine care. Digital health and specifically remote patient monitoring (RPM) offer a way to track and manage these challenges effectively, increasing access to supportive care. Methods: Prospective, observational cohort of 7323 adult patients with cancer participating in an RPM pathway across 110 hospitals in France and Belgium between Jun-2022 and Dec-2024. Patients were grouped by age ( < 40 vs. ≥40). At baseline, demographic, clinical, and social and behavioral data were collected. Longitudinal symptom burden (e.g., anxiety, pain, nausea) was assessed using validated patient-reported outcomes (PRO-CTCAE). High symptom burden was defined as PRO-CTCAE grade ≥3. QoL was measured by EORCT QLQ-C30 summary score. Linear mixed models, adjusted for relevant covariates, were used to compare changes in symptom burden over 12 weeks between age groups. Results: Younger patients (n = 350 pts < 40 years) were more often female (77 vs 62%, p < 0.001) and with localized disease (55 vs 45%, p < 0.001). The rate of breast, lung, colorectal and pancreatic cancers represented respectively 157%, 27%, 57% and 17% of the proportion in older adults (p < 0.001). Younger patients also presented with more unfavorable social and behavioral characteristics including higher alcohol consumption (26.3 vs. 15.3%, p= 0.005), tobacco consumption (23.2 vs. 13.8%, p < 0.001), unemployment (17.7 vs 7.2%, p < 0.001) and financial insecurity (23.2 vs 10.9%, p < 0.001). Similar QoL was found at baseline (mean [SD] 76.9 [16.8] vs 76.1 [17.0], p = 0.84). Adherence to RPM surveys was lower in the younger group (74 vs 84%, p = 0.001), who took also on average longer to answer (22 vs 10h, p<0.001). Younger patients had higher early (week 1 to 3) symptom burden (anxiety 16.7 vs 10.6%, p = 0.001], fatigue [36.1 vs 30.6, p = 0.05], nausea [30.4 vs 18.6%, p < 0.001], anorexia [16.7 vs 10.6, p = 0.004] and performance status decline [26.8 vs 18.7%, p = 0.012). At 12 weeks, symptom burden improved in both groups, and the between-group difference was no longer significant. Conclusions: In this large, multi-institutional cohort, younger patients faced unique physical, psychological and behavioral challenges and experienced higher early symptom burden. Interestingly, by 12 weeks, both groups demonstrated symptomatic improvement, with no remaining differential across age groups. These findings suggest that RPM and supportive interventions may help mitigate disparities in symptom burden over time.