The risk of epithelial ovarian cancer (EOC) is increased by pelvic inflammatory disease (PID) history, according to a recent study published in the American Journal of Obstetrics & Gynecology.
Takeaways
- The study found a significant association between a history of pelvic inflammatory disease (PID) and an increased risk of epithelial ovarian cancer (EOC). This highlights the potential role of PID in the development of EOC.
- Early identification of EOC remains challenging because of a lack of presenting symptoms. The absence of a validated screening method contributes to diagnoses occurring at later stages when tumors have spread within the abdominal cavity.
- While there is evidence linking PID to EOC risk, it is currently limited. This emphasizes the need for further research to explore the biological explanations and temporal relations between PID and EOC.
- The investigators conducted a population-based case-control study in Sweden, involving women with an EOC diagnosis from 1999 to 2020. This approach allowed for a comprehensive examination of the association between PID history and EOC risk.
- The study revealed that PID history was specifically associated with an increased risk of serious carcinoma and clear cell carcinoma. No significant associations were identified for other histotypes, indicating potential variations in the impact of PID on different types of EOC.
EOC is difficult to identify in its early stages because of a lack of presenting symptoms. A validated screening method has not been established, and diagnosis often occurs when tumors have already spread throughout the abdominal cavity.
PID, caused by ascending microorganisms from the lower genital tract, presents as inflammation of the female reproductive organs.Approximately 15% to 20% of all cancers have been linked to microorganisms.There is evidence associating PID with EOC risk, but this evidence is currently limited.
To determine the association between PID history and EOC risk, investigators conducted a population-based case-control study. Participants included women residing in Sweden with an EOC diagnosis from January 1, 1999, to December 31, 2020.
The Swedish National Cancer Register was evaluated to determine cases. Women with EOC were considered cases, with tumor sites including ovary, fallopian tubes, and primary peritoneum. These patients were matched with controls using the Swedish Register of the Total Population.
Exclusion criteria included diagnosis before 1999, not being a Swedish resident since aged 18 years, and having undergone bilateral oophorectomy, bilateral salpingo-oophorectomy, or major gynecologic surgery before the index date. PID was determined using the National Patient Register, which included inpatient and specialized outpatient care.
Investigators defined PID as female upper reproductive tract inflammation. This included salpingitis, oophoritis, and tubo-ovarian abscess diagnosed using International Classification of Diseases, Ninth Revision (ICD-9) and ICD-10 codes.
Covariates included age, education level, parity, menopausal hormone therapy, hormonal contraceptives, and previous gynecologic surgical procedures. Categories for exposures included number of PID episodes, number of children, and education level.
There were 15,072 cases and 141,322 controls included in the final analysis. Of cases, 83.4% had ovarian cancer, 11.4% tubal, and 5.2% primary peritoneal cancer. Women diagnosed with EOC were aged a mean 65.5 years.
The most common histotype was serious EOC in 60.4% of women with EOC, followed by adenocarcinoma not otherwise specified in 13.3%, endometrioid in 10.2%, mucinous in 7.7%, clear cell in 5.2%, and unspecified carcinoma in 3.1%.
One or more clinically verified PID episodes were reported in 1.1% of cases and 0.9% of controls. Cases and controls were aged a mean 43.3 and 41.8 years at first PID, respectively. A single PID episode was reported in 71.4% vs 77.6%, respectively, 2 episodes in 19% vs 16.5%, respectively, and 3 or more episodes in 9.5% vs 5.8%, respectively.
PID history was associated with increased EOC risk, with an adjusted odds ratio (aOR) of 1.39. For serious carcinoma risk, the aOR was 1.46, and for clear cell carcinoma risk the aOR was 1.83. Significant associations were not identified for any other histotypes.
These results indicated an association between PID history and EOC risk. Investigators recommended future studies on biological explanations and temporal relations be conducted.
Reference
Jonsson S, Jonsson H, Lundin E, et al. Pelvic inflammatory disease and risk of epithelial ovarian cancer: a national population-based case-control study in Sweden. Am J Obstet Gynecol. 2024;230:75.e1-15. doi:10.1016/j.ajog.2023.09.094
