Histologic distribution of borderline ovarian tumors worldwide: a systematic review

Objective: The histologic types of borderline ovarian tumors (BOTs) exhibit striking differences in clinical behavior and prognosis. Yet, there is no information available on the histologic distribution of BOTs according to geographic region. The purpose of this study was to systematically review this issue worldwide. Methods: A comprehensive search of the literature was conducted using electronic databases. Studies were eligible if BOTs were investigated and the histologic distribution of the data was shown. The studies were grouped by geographic region and totaled by country. Results: Of 487 potentially relevant studies, 51 met our inclusion criteria, as follows: 8 studies from North America (2 countries); 26 studies from Europe (14 countries); 7 studies from the Middle East (3 countries); and 10 studies from East Asia (5 countries). The histologic distribution of BOTs was considerably different in different parts of the world, but follows specific patterns. In general, serous-type BOTs were the predominantly identified histology in North America, the Middle East, and Europe, while mucinous-type BOTs predominated in East Asia. Conclusion: Significant geographic variation is evident among BOT histology in different parts of the world. More research is needed to understand this phenomenon.