Objective: This study aimed to explore whether young adults with cancer have different functioning compared to older age groups with cancer. Methods: This study is a cross-sectional study including 654 adults (≥18 years) with cancer. Exposure was age groups categorised as (1) young adults (n = 121) = 18-39 years; (2) middle-aged adults (n = 406) = 40-64 years; and (3) older people (n = 127) = ≥65 years. Outcomes were physical, role, social and cognitive functioning. Analyses consisted of linear regression models. Results: Middle-aged adults had a statistically significant worse physical functioning compared to young adults (À3.90: [95% CI: À6.84; À0.95]). The older age group also had a statistically significant worse physical functioning compared to young adults (À7.63: [95% CI: À11.29; À3.96]). Young adults had statistically significant lower role functioning (À7.11: [95% CI: À1.13; À13.08]) and cognitive functioning (À13.82:[95% CI: À7.35; À20.29]) compared to the older age group. There was no statistically significant difference in social functioning between the age groups. Conclusion:Young adults with cancer seem to have other functioning problems compared with higher age groups. These findings support current research regarding the need to develop age-specific and appropriate rehabilitation services for young adults with cancer.

Purpose: To explore whether young adults with cancer have different activity limitations and participation restrictions compared to older age groups with cancer. Methods: A cross-sectional study including 654 people with cancer participating in a rehabilitation stay. Participants were in the age groups: 1) Young adults (n=121) = 18-39 years; 2) Middle-aged (n=406) = 40-64 years; and 3) older people (n=127) = ≥65 years. Outcomes were activity limitations and participation restrictions encompassing physical, role, social, and cognitive functioning, measured using the European Organization for Research and Treatment of Cancer Quality-of-Life Questionnaire Core 30. Mean differences between age groups were calculated using linear regression analyses. Results: Young adults had a mean age of 32.1 years (SD = 5.1); middle-aged adults 53.4 years (SD = 6.8); and the older people 71.1 years (SD = 4.8). The majority of the participants were women (81.9%) with breast cancer (42.9%). Young adults had a statistically significant higher physical functioning compared to those middle-aged (-3.90: (95% CI: -6.84; -0.95)) and the older age group (-7.63: (95% CI: -11.29; -3.96)). Young adults had statistically significant lower role functioning (7.11: (95% CI: 1.13; 13.08)) and cognitive functioning (13.82: (95% CI: 7.35; 20.29)) compared to older people. There was no statistically significant difference in social functioning between the age groups. Conclusion: Young adults had different activity limitations and participation restrictions compared with higher age groups. Our findings suggest the need for further research and an increased clinical rehabilitation focus on different activity and participation challenges across age groups.