Mastitis in Older Women Linked to Subsequent Breast Cancer

TOPLINE:
Mastitis in women over 50 years of age is a risk factor for development of breast cancer, according to a large retrospective cohort study of 2.4 million German women. Mastitis is an inflammation of breast tissue typically caused by a Staph infection.
METHODOLOGY:
This study was a retrospective cohort of 2,381,594 women in 315 office-based gynaecology practices in Germany (2005-2021).
Women with mastitis (n = 14,892) were compared with women without mastitis (n = 14,892) and followed from 7 months to 10 years.
The control group without mastitis was propensity score-matched on age, index year, average yearly consultation frequency during the follow-up period, and coexisting conditions.
The primary outcome was an initial diagnosis of breast cancer.
TAKEAWAY:
Over the follow-up period, 2.9% of the mastitis cohort and 2.4% of the matched non-mastitis cohort developed breast cancer.
While Cox regression analysis uncovered a significant association between mastitis and breast cancer (hazard ratio, 1.37; 95% CI, 1.11-1.70), the age-stratified analysis revealed a significant association only among women aged > 50 years. They had a 73% increase in the risk compared with women without mastitis (hazard ratio, 1.73; 95% CI, 1.25-2.40).
Women aged ≤ 50 years had no significant increase in the risk for breast cancer.
IN PRACTICE:
The authors concluded that “The findings of our retrospective cohort study support an association between mastitis and subsequent breast cancer diagnoses in women aged > 50 years. The pathophysiological basis and possibility of confounders however requires further investigation.”
SOURCE:
The corresponding author is Karel Kostev, University Hospital Marburg, Philipps-University, Marburg, Germany. The study appeared in Cancer Causes & Control.
LIMITATIONS:
Limitations included a retrospective observational design and possibility of unmeasured confounding factors.
DISCLOSURES:
The authors reported no conflicts of interest. The study received no funding.
 
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