The Role of Crohn Disease on Breast Cancer Incidence: A Clinical Analysis.

Background: Crohn disease is a chronic inflammatory disease that can affect the entire gastrointestinal tract. The pathophysiology of this disease characteristically involves transmural inflammation, which predisposes patients to various gastrointestinal cancers such as colon cancer. Although the increased risk of gastrointestinal cancers in Crohn disease has been well established, the risk of extra-gastrointestinal cancers remains unknown. We sought to study the risk of breast cancer in patients with Crohn disease.

Methods: The data for this retrospective study were compiled using the International Classification of Disease Ninth Revision (ICD-9) and ICD 10th Revision (ICD-10) codes from the national Health Insurance Portability and Accountability Act (HIPAA)-compliant PearlDiver database from 2010 to 2019. Patients were matched for age, sex, and Charlson Comorbidity Index (CCI). Statistical analyses were implemented to assess Chi-squared, logistic regression, and odds ratio.

Results: The database query resulted in 70,027 patients in both the control and Crohn disease groups. The incidence of breast cancer was 4,087 in the control group compared to 654 in the Crohn disease group. The P value was < 2.2 × 10^-16 and the odds ratio was 0.15 (95% confidence interval (CI)). Patients without Crohn disease had an increased prevalence of breast cancer throughout all age ranges compared to patients with Crohn disease. Additionally, patients without Crohn disease had higher rates of breast cancer throughout the four major regions of the United States. In terms of healthcare costs, patients with breast cancer and a history of Crohn disease paid $23.87 more per hospital visit compared to patients with breast cancer and no history of Crohn disease.

Conclusions: The results of this study indicate a statistically significant correlation between Crohn disease and a reduced incidence of breast cancer. This finding is true across all age groups and across the United States. Further study is required to investigate a possible mechanism between the pathophysiology of Crohn disease ultimately leading to reduced tumorigenesis in the breast.