Matsuo K, et al. - In this retrospective population-based study, researchers examined the Surveillance, Epidemiology, and End Results Program from 1988 to 2000, to distinguish mucinous borderline ovarian tumor (mucinous-BOT) and invasive well-differentiated mucinous ovarian cancer (mucinous-OC) in terms of clinico-pathological characteristics and outcomes. Using propensity score matching and multivariable analysis, they analyzed 2130 mucinous-BOT and 581 mucinous-OC cases. Findings revealed distinct variations in clinical features and patient survival between stage I mucinous-BOT and stage I invasive well-differentiated mucinous-OC. Older women, Eastern U.S. residents, and those having undergone hysterectomy or lymphadenectomy were more likely to be presented with mucinous-OC vs mucinous-BOT on multivariable analysis. Following propensity score matching, a significantly poorer cause-specific survival (CSS) was found in women with mucinous-OC vs those with mucinous-BOT on multivariable analysis (10-year rates: 92.7% vs 97.5%, adjusted-hazard ratio [HR] 2.03, P = 0.007).