Objective: To determine changes in the characteristics of low-grade serous ovarian cancer (LGSOC) and serous borderline ovarian tumor (serous-BOT) in a time-specific manner.
Methods: We conducted a population-based retrospective study examining the Surveillance, Epidemiology, and End Results Program from 1988 to 2000. Trends, demographics, and outcomes of 775 women with well-differentiated serous ovarian cancer, used as a surrogate for LGSOC, were compared to 3937 women with serous-BOT.
Results: In the multivariable analysis, women with LGSOC were more likely to be older, have stage II-IV disease, and have undergone hysterectomy at surgery, but less likely to be a Western U.S. resident compared to those with serous-BOT (all, adjusted-P < 0.05). During the study period, the number of LGSOCs decreased by 25.9%, particularly stage I disease (37.6% relative decrease) compared to stage II-IV disease (21.1% relative decrease) (all, P < 0.05). With a median follow-up of 16.9 years, there was a decreasing trend in the 15-year overall survival rates among LGSOC (28.7% relative decrease, P = 0.056) but not in serous-BOT (2.5% relative increase, P = 0.416) as a whole cohort. The magnitude of hazard risk from all-cause death for women with LGSOC compared to those with serous-BOT increased by 68.9% from 1988 to 2000 (P < 0.001). LGSOC remained an independent prognostic factor for decreased overall survival compared to serous-BOT (adjusted-P < 0.05).
Conclusion: Our study suggests that the decreasing number and survival of LGSOC over time may be due to a diagnosis-shift from LGSOC to serous-BOT. Given the distinct characteristics and outcomes of LGSOC compared to serous-BOT, our study endorses the importance of making the correct diagnosis upfront. Whether this diagnostic-shift supports a hypothesis that serous-BOT is a precursor lesion of LGSOC merits further investigation.