Association of cancer with functional decline at old age: a longitudinal study in Danish twins

Afsaneh Mohammadnejad; Jesper Ryg; Marianne Ewertz; Juulia Jylhävä; Jacob vB Hjelmborg; Angéline Galvin

doi:10.1177/14034948241240823

Association of cancer with functional decline at old age: a longitudinal study in Danish twins

Scand J Public Health. 2024 Apr 3:14034948241240823. doi: 10.1177/14034948241240823. Online ahead of print.

Authors

Afsaneh Mohammadnejad¹, Jesper Ryg^{2

3

4}, Marianne Ewertz^{2

4}, Juulia Jylhävä^{5

6}, Jacob vB Hjelmborg^{1

7}, Angéline Galvin^{1

8}

Affiliations

¹ Epidemiology, Biostatistics and Biodemography, Department of Public Health, University of Southern Denmark, Denmark.
² Academy of Geriatric Cancer Research (AgeCare), Odense University Hospital, Denmark.
³ Department of Geriatric Medicine, Odense University Hospital, Denmark.
⁴ Department of Clinical Research, University of Southern Denmark, Denmark.
⁵ Department of Medical Epidemiology and Biostatistics, Karolinska Institutet, Sweden.
⁶ Faculty of Social Sciences, Unit of Health Sciences and Gerontology Research Center, University of Tampere, Finland.
⁷ The Danish Twin Registry, University of Southern Denmark, Denmark.
⁸ University of Bordeaux, Inserm, Bordeaux Population Health Research Center, Epicene Team, France.

PMID: 38570302
DOI: 10.1177/14034948241240823

Abstract

Introduction: There is evidence that older adults with cancer have a higher risk of functional decline than cancer-free older adults. However, few studies are longitudinal, and none are twin studies. Thus, we aimed to investigate the relationship between cancer and functional decline in older adult (aged 70+ years) twins.

Materials and methods: Cancer cases in the Longitudinal Study of Aging Danish Twins were identified through the Danish Cancer Registry. Functional status was assessed using hand grip strength (6 years follow-up), and self-reported questions on mobility (10 years follow-up), and cut-offs were defined to assess functional decline. Cox regression models were performed for all the individual twins. In addition, we extended the analysis to discordant twin pairs (twin pairs with one having cancer and the other being cancer-free), to control to a certain extent for (unmeasured) shared confounders (genetic and environmental factors).

Results: The analysis based on individual twins showed that individual twins with cancer are at increased hazard of worsening hand grip strength (hazard ratio (HR) 1.37, 95% confidence interval (CI) 1.04, 1.80) than cancer-free twins. Among the discordant twin pairs, twins with cancer had a higher hazard of worsening hand grip strength (HR 3.50, 95% CI 1.15, 10.63) than cancer-free cotwins. In contrast, there was no evidence of a difference between the hazard of experiencing mobility decline for twins with cancer compared with cancer-free twins, in both individual twins and discordant twin pairs analyses.

Discussion: Cancer was associated with hand grip strength functional decline in old individual twins and discordant pairs. Our results strengthen the importance of comprehensive geriatric assessment in older adults with cancer, as well as the importance of routine assessment of functional status. Promoting physical activity through exercise training programmes could enable the prevention of functional decline in older adults with cancer.

Keywords: Older adults; cancer; functional decline; hand grip strength; mobility; twins.