Pelvic inflammatory disease increases the risk of a second primary malignancy in patients with cervical cancer treated by surgery alone

As the number of long-term cervical cancer survivors continues to increase because of improvements in treatment, concerns about second primary malignancy have grown. The high-risk area of second primary cancers in cervical cancer survivors is the pelvis. Pelvic inflammatory disease (PID) could be a useful marker for gynecological cancers. Thus, we designed a large-scale, nationwide, controlled cohort study to investigate whether PID or other risk factors increased the risk of second primary cancers in patients with cervical cancer treated by surgery alone.Between 2000 and 2010, a total of 24,444 cervical cancer patients were identified using the Registry Data for Catastrophic Illness and the National Health Insurance Research Database (NHIRD) of Taiwan. Patients who received definite surgery were selected. To exclude the effect on second primary malignancy by treatment modalities, all cervical patients who ever having received adjuvant or definite radiotherapy or chemotherapy for primary cervical cancer were excluded. Finally, 3860 cervical cancer patients treated by surgery alone without adjuvant treatments were analyzed.Cox proportional hazards model was used for multivariate analysis and the Kaplan-Meier method was used to assess the cumulative risks. Regarding the incidence of second primary cancers, the standardized incidence ratio (SIR) was used.The median follow-up time was 56.6 months. The 6-year cumulative risk of second primary cancers is 0.16% and 0.12% for PID and without PID, respectively. After adjustment for confounders, age of less than 50 years, the presence of diabetes mellitus, and PID were significantly positivity associated with the risk of second primary cancers. The hazard ratios (HRs) of age less than 50 years, diabetes mellitus, and PID were 1.38 (95% CI = 1.11-2.04), 1.40 (95% CI = 1.06-1.85), and 1.35 (95% CI = 1.00-1.81), respectively. A higher incidence of second primary cancers was observed in the genitals, bladder, and colon.In conclusion, the incidence of second primary cancers was higher in the genitals, bladder, and colon in patients with cervical cancer treated with surgery alone. The patients with PID had a higher risk of second primary cancers.