Risk of bullous pemphigoid in patients with cancer

Abstract

Summary Bullous pemphigoid (BP) is a skin condition that causes rashes and itchy blistering in the skin. It is caused by the individual developing antibodies against their own skin – known as autoimmunity. Disease flare‐ups cause extreme discomfort, requiring effort from dermatologists and the family to care for the patients. People diagnosed with BP tend to be suffering already from other medical conditions such as diabetes, neurological diseases including Parkinson's and Alzheimer's and cardiovascular disease, and these are known risk factors for BP. However, the relationship between cancer and BP remains controversial. This study, from Taiwan, aimed to find out if there is an increased risk for subsequent BP among cancer patients. It also aimed to find out which type of cancer might have the strongest relationship. The authors used the Taiwan National Health Insurance Database, which includes one million randomly sampled beneficiaries, to perform this study. A total of 36,838 cancer patients and 147,352 people without cancer were chosen (the latter as a control group). To calculate incidence, broadly meaning rates of new cases of a disease, scientists calculate the incidence in ‘person years’ which takes into account both the number of people in the study and the amount of time each person spends in the study, and then how many of these develop the disease during the study time. Using this method, between 2002 and 2011, 22 people developed BP among the cancer patients (17.2 per 100,000 person‐years) and 171 among the control group (19.8 per 100,000 person‐years). The incidence of BP in the cancer patients was not higher than in the controls. Age, diabetes mellitus, and cerebrovascular disease were observed to be risk factors for BP. The study also observed that patients with brain and other nervous system cancers had a relatively higher incidence of subsequent BP (128.3 per 100,000 person‐years) than those with other types of cancer. The findings of this study provide solid evidence that cancer is not a risk factor for BP.