Urticaria Linked to Higher Cancer Risk, Study Finds

TOPLINE:

Compared with the general population, patients with urticaria had a 49% higher risk of developing cancer in the first year following diagnosis, which decreased to 6% in subsequent years, in a cohort study using Danish healthcare databases.

METHODOLOGY:

• Researchers conducted a retrospective cohort study using data from Danish healthcare registries and compared the incident cancer risk between patients with urticaria and the risk in the general population.
• They identified 87,507 patients (58% women) with a primary or secondary first-time hospital outpatient clinic, emergency room, or inpatient diagnosis of urticaria between 1980 and 2022, who were followed for a median of 10.1 years.
• Incident cancers, including nonmelanoma skin cancer, were identified using the Danish Cancer Registry and classified by the extent of spread at the time of diagnosis.
• This study computed the absolute cancer risk within the first year of an urticaria diagnosis and standardized incidence ratios (SIRs), with 95% CIs standardized to Danish national cancer rates.

TAKEAWAY:

• For the first year of follow-up, the absolute risk for all cancer types was 0.7%, and it was 29.5% for subsequent years. The overall SIR for all types of cancer was 1.09 (95% CI, 1.06-1.11), which was based on 7788 observed cancer cases compared with 7161 cases expected over the entire follow-up period.
• Within the first year of follow-up, 588 patients with urticaria were diagnosed with cancer, for an SIR of 1.49 (95% CI, 1.38-1.62) for all cancer types.
• After the first year, the SIR for all cancer sites decreased and stabilized at 1.06 (95% CI, 1.04-1.09), with 7200 observed cancer cases.
• The risk was highest for hematological cancers in the first year, particularly Hodgkin lymphoma (SIR, 5.35; 95% CI, 2.56-9.85).

IN PRACTICE:

“Our study suggests that urticaria may be a marker of occult cancer and that it is associated with a slightly increased long-term cancer risk,” the authors wrote.

SOURCE:

The study was led by Sissel B.T. Sørensen, Departments of Dermatology and Rheumatology, Aarhus University Hospital, Aarhus, Denmark. It was published online on June 27, 2024, in the British Journal of Dermatology.

LIMITATIONS:

The study is limited by its observational design and reliance on registry data, which may be subject to misclassification or incomplete information. Additionally, the study could not assess individual patient factors such as lifestyle or genetic predispositions that may influence cancer risk, and the results may not be generalizable to other populations. Finally, the exact biologic mechanisms linking urticaria and cancer remain unclear, warranting further investigation.

DISCLOSURES:

The study did not receive any funding. The authors reported that they had no relevant conflicts of interest.

This article was created using several editorial tools, including AI, as part of the process. Human editors reviewed this content before publication.