Frozen shoulder and risk of cancer: a population-based cohort study

Frozen shoulder might be a complication or a presenting symptom of cancer. We examined the risk of a cancer diagnosis after an incident diagnosis of frozen shoulder.

We used prospectively collected data from Danish registries to identify patients with frozen shoulder during 1995-2013 and followed them for the development of cancer.

We observed 2572 incident cancers among 29 098 frozen shoulder patients. The expected number of incident cancers in the general population was 2434. The 6-month cumulative incidence of any cancer was 0.70%, corresponding to a standardised incidence ratio (SIR) of 1.38 (95% confidence interval (CI): 1.19-1.58). Risk increases were highest for lung cancer (SIR=2.19, 95% CI: 1.48-3.13), breast cancer (SIR=1.51, 95% CI: 1.02-2.15), and non-Hodgkin's lymphoma (SIR=2.28, 95% CI: 1.09-4.20). The cumulative incidence of any cancer during the remainder of follow-up (>6 months to a maximum 18.9 years) was 24.8% with an SIR of 1.04 (95% CI: 1.00-1.08).

Frozen shoulder might be an early predictor for a subsequent cancer diagnosis.