January 20, 2012 — The presence of chronic urticaria increased the risk for cancer among Taiwanese patients, according to the findings of a recent retrospective population-based cohort study.
Yi-Ju Chen, MD, from National Yang-Ming University in Taipei, Taiwan, and colleagues published their findings in the January issue of the Archives of Dermatology.
The authors mention that the link between chronic urticaria and cancer has not yet been definitively confirmed. "Although there have been case reports of urticaria associated with malignant tumor, a study of more than 1000 patients showed no association between chronic urticaria and malignant tumor," the authors write. "Only limited epidemiologic information is available about the exact extent of the association between chronic urticaria and cancer."
Among 12,720 eligible patients who were observed for a period of 69,305 person-years, chronic urticaria was associated with an increased risk for cancer (standardized incidence ratio [SIR], 2.2; 95% confidence interval [CI], 2.0 - 2.3), and this risk was similar among men (SIR, 2.1; 95% CI, 1.9 - 2.3) and women (SIR, 2.3; 95% CI, 2.1 - 2.6). The greatest risk for cancer was observed in the 20- to 39-year-old (SIR, 5.8; 95% CI, 4.1 - 8.1) and 40- to 59-year-old (SIR, 3.8; 95% CI, 3.3 - 4.3) age groups.
The authors based the study on data obtained from the National Health Insurance Research Database in Taiwan between January 1, 1996, and December 31, 2008. The authors included patients with a diagnosis of urticaria who had received long-term antihistamine therapy, defined as the use of antihistamines for at least 6 months during a 2-year period. The authors excluded patients who did not have a diagnosis of cancer as confirmed by the issuance of a cancer catastrophic illness certificate.
Chronic urticaria was associated with an increased risk for hematologic cancer (SIR, 4.1; 95% CI, 3.1 - 5.4). The risk for hematologic cancer among patients with chronic urticaria tended to decrease with age, with the highest risk observed among patients younger than 20 years (SIR, 7.0; 95% CI, 2.8 - 14.4). The risk for hematologic cancer was highest in the first year after of a diagnosis of chronic urticaria (SIR, 16.5; 95% CI, 11.4 - 23.2).
In addition, chronic urticaria was also associated with an increased risk for nonhematologic cancer (SIR, 2.1; 95% CI, 1.9 - 2.3). Among nonhematologic cancers, brain (SIR, 5.0; 95% CI, 2.4 - 9.2), retroperitoneal (SIR, 5.0; 95% CI, 1.6 - 11.7), vulvar (SIR, 4.0; 95% CI, 1.1 - 10.2), and kidney and other urinary system (SIR, 3.3; 95% CI, 2.2 - 4.8) cancers were most significantly associated with chronic urticaria.
Limitations of the study include lack of data regarding patient information including signs and symptoms, laboratory abnormalities, chronic common urticarial vs urticarial vasculitis, and personal information such as family history of cancer, body mass index, lifestyle choices, and smoking and alcohol use.
The authors note that previous studies did not examine the relationship between the onset age of chronic urticaria and cancer risk. "Our study demonstrated that younger patients (aged <40 years) tend to have the greatest risk of cancer development, especially for hematologic cancers" the authors write. "These results suggest that thorough and periodic assessment may be needed in younger patients."
The study was supported by grants from the Tai-chung Veterans General Hospital. The authors have disclosed no relevant financial relationships.
Arch Dermatol. 2012;148:103-108. Abstract
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