# Association of Autoimmune Diseases With Pancreatic Cancer: A Nationwide Follow‐Up Study From Sweden

## TL;DR

This study finds that certain autoimmune diseases are linked to a higher risk of developing and dying from pancreatic cancer in Sweden.

## Contribution

The study identifies new associations between specific autoimmune diseases and increased pancreatic cancer risk and mortality.

## Key findings

- 12 autoimmune diseases were positively correlated with pancreatic cancer incidence.
- 15 autoimmune diseases were linked to higher pancreatic cancer mortality.
- The risk of pancreatic cancer in patients with autoimmune diseases was highest within the first year of diagnosis.

## Abstract

The incidence of pancreatic cancer (PC) and autoimmune diseases (ADs) has been increasing worldwide. While certain associations between specific ADs, such as pancreatitis, and PC have long been well confirmed, population‐focused research investigating the broader spectrum of ADs and their relationship with PC risk remains limited.

We implemented a cohort study based on population data to analyze the relationships between ADs and PC susceptibility. Diagnostic information on 43 ADs was obtained from the Swedish Inpatient Register (1964–2018), while cancer incidence and mortality data were sourced from the National Cancer Registry and Cause of Death Register starting in 1997. Relative cancer risks were quantified using standardized incidence ratios (SIRs) and standardized mortality ratios (SMRs).

Within the study's total population of 16.4 million, 1.1 million cases of ADs were identified, and 3257 patients were later diagnosed with PC accounting for 5.42% of all cancer cases in the cohort. The SIRs for PC in patients with ADs were 1.24 (men) and 1.19 (women); 12 ADs were positively correlated with the incidence of PC. The SMRs for PC in patients with ADs were 1.28 (men) and 1.22 (women); 15 ADs were positively correlated with PC mortality. When the follow‐up time was less than 1 year, the overall risk of PC in patients with ADs was 3.88; over 10 years, the risk reached 1.12.

We have newly discovered the relationship between several ADs and the risk of PC incidence and mortality, including discoid lupus erythematosus, lupoid hepatitis, giant‐cell arteritis, and rheumatic fever. The results of this study back the notion that ADs may have a role in promoting the onset of PC.

Graphic abstract illustrating the nationwide cohort design used to investigate the association between autoimmune diseases and the risk of pancreatic cancer in Sweden.