(PM P6) Incomplete Cytoreductive Surgery for Appendiceal and Colorectal Peritoneal Carcinomatosis: Characteristics and Outcomes of an Overlooked Group

Background: Cytoreductive surgery (CRS) followed by intraperitoneal chemotherapy (IPC) may prolong survival for select patients with appendiceal and colorectal peritoneal carcinomatosis (PC). However, little has been reported regarding outcomes following incomplete cytoreduction.

Methods: Patients who were explored with the intention of optimal CRS but had incomplete CRS (CC 2/3) for appendiceal and colorectal PC between 2008 and 2015 at a single academic center were reviewed. Demographics, surgical details, perioperative complications, and overall survival (OS) were analyzed. Subgroup analysis was performed comparing well-differentiated appendiceal cancer (WD), moderate/poorly-differentiated appendiceal cancer (M/PD), and any colorectal cancer (CRC).

Results: Fifty-eight patients were included (11 CC2, 47 CC3). Patients in the WD group were less likely to receive neoadjuvant systemic chemotherapy and had longer operative times compared to patients with M/PD or CRC. The estimated 3-year OS from diagnosis for the WD, M/PD, and CRC subgroups was 86%, 33%, and 11%, respectively (p=0.010). Twenty (11.6%) patients required at least one subsequent palliative procedure, and the time to that intervention was significantly longer for the WD group compared to the M/PD or CRC groups. Grade 3-4 complications occurred in 5.8% of patients and were not associated with a difference in OS. Four percent (4%) of patients received palliative IPC postoperatively and those patients had similar overall survival compared to those who did not receive postoperative IPC.

Conclusion: Incomplete CRS is associated with low morbidity, a low incidence of subsequent palliative procedures, and better than expected overall survival. Oncologic outcomes correlated with histologic subtype; patients in the WD group had superior outcomes. These data may help guide expectations in the setting of incomplete CRS.