Intraperitoneal disease dissemination patterns are associated with residual disease, extent of surgery, and molecular subtypes in advanced ovarian cancer.

OBJECTIVE: To investigate the association between intraperitoneal (IP) disease dissemination patterns, residual disease (RD), surgical complexity, and molecular subtypes in advanced high-grade serous ovarian cancer (HGSOC).
METHODS: 741 patients with operable stage III-IV HGSOC undergoing primary debulking surgery at Mayo Clinic from 1994 to 2011 were categorized into four mutually exclusive IP disease dissemination patterns: upper abdominal (60%), miliary (16%), lower abdominal (15%), and pelvic (9%). Surgical complexity was classified as high, intermediate, or low; RD status was defined as 0, 0.1-0.5, 0.6-1.0, or >1cm; molecular subtype assignments were derived from expression profiling of tumors from 334 patients.
RESULTS: Patients with either miliary or upper abdominal dissemination patterns were less likely to achieve RD0 compared to patients with pelvic and lower abdominal dissemination patterns (25% vs. 9% and 62%, each P<0.001) despite higher surgical complexity (39% vs. 6% and 20%, each P<0.001). Among the subset with molecular subtype data, patients with mesenchymal subtype of tumors were more likely to have upper abdominal or miliary dissemination patterns compared to patients with differentiated, proliferative, or immunoreactive subtypes (90% vs. 77%, 70%, 69%, respectively, P<0.05).
CONCLUSIONS: IP disease dissemination patterns are associated with RD, surgical complexity, and tumor molecular subtypes. Patients with upper abdominal or miliary dissemination patterns are more likely to have mesenchymal HGSOC and in turn achieve lower rates of complete resection. This provides a plausible model for how the biologic behavior of molecular subtypes is manifest in disease and oncologic outcomes.