Demographic, social and lifestyle risk factors for cancer registry-notified cancer of unknown primary site (CUP)

Authors

C Vajdic, University of New South Wales
O Perez-Concha, University of New South Wales
Timothy Dobbins, University of New South Wales, University of Sydney
Robyn L. Ward, University of SydneyFollow
Andrea L. Schaffer, University of New South Wales
M van Leeuwen, University of New South Wales
Joel J. Rhee, University of New South Wales, University of WollongongFollow
M Laaksonen, University of New South Wales
G Craigen, Cancer Voices NSW
Sallie-Anne Pearson, University of New South Wales

RIS ID

135150

Publication Details

Vajdic, C., Perez-Concha, O., Dobbins, T., Ward, R. L., Schaffer, A. L., van Leeuwen, M. T., Rhee, J. J., Laaksonen, M. A., Craigen, G. & Pearson, S. A. (2019). Demographic, social and lifestyle risk factors for cancer registry-notified cancer of unknown primary site (CUP). Cancer Epidemiology, 60 156-161.

Abstract

Background: Little is known about the risk factors for cancer of unknown primary site (CUP). We examined the demographic, social and lifestyle risk factors for CUP in a prospective cohort of 266,724 people aged 45 years and over in New South Wales, Australia.

Methods: Baseline questionnaire data were linked to cancer registration, hospitalisation, emergency department admission, and mortality data. We compared individuals with incident cancer registry-notified CUP (n = 327) to two sets of controls randomly selected (3:1) using incidence density sampling with replacement: (i) incident cancer registry-notified metastatic cancer of known primary site (n = 977) and (ii) general cohort population (n = 981). We used conditional logistic regression to estimate adjusted odds ratios (ORs) and 95% confidence intervals (CIs).

Results: In a fully adjusted model incorporating self-rated overall health and comorbidity, people diagnosed with CUP were more likely to be older (OR 1.05, 95% CI 1.04-1.07 per year) and more likely to have low educational attainment (OR 1.77, 95% CI 1.24-2.53) than those diagnosed with metastatic cancer of known primary. Similarly, compared to general cohort population controls, people diagnosed with CUP were older (OR 1.10, 95% CI 1.08-1.12 per year), of low educational attainment (OR 1.69, 95% CI 1.08-2.64), and current (OR 3.42, 95% CI 1.81-6.47) or former (OR 1.95, 95% CI 1.33-2.86) smokers.

Conclusion: The consistent association with educational attainment suggests low health literacy may play a role in CUP diagnosis. These findings highlight the need to develop strategies to achieve earlier identification of diagnostically challenging malignancies in people with low health literacy.