The natural history and role of surgical cytoreduction and systemic chemotherapy in high-grade mucinous adenocarcinomas of the appendix

199 Background: The natural history, clinical presentation, and impact of cytoreductive surgery (CRS) or systemic chemotherapy for high grade MAA has been poorly studied. Methods: A retrospective chart review of patients (pts) with moderate or poorly differentiated AA was completed from 1994-2010. Radiographic response was assessed semi-quantitatively form physician records and complete cytoreductive surgery (CRS) was defined as a completeness of cytoreduction score of 0 or 1. For CRS and chemotherapy subgroups efficacy endpoints were calculated from date of CRS or first chemotherapy dose, respectively. Results: 288 (136 moderate and 152 poor grade) pts were identified with a median age of 52 years (range: 25-82). Mucinous histology was present in 110 pts (38%) and differed by grade: 55% of moderate and 23% of poor. Stage IV presentation (n=163) occurred in 76% of poor grade but only 35% of moderate grade. Both median OS (4.5 vs. 2.7 yrs, P=0.04) and median OS for the stage IV subgroup (3 vs 1.9yrs, P=0.005) were improved for MAA vs. non-MAA. Moderate compared to poor grade had improved median OS (3.7 vs 1.9 yrs, P=0.002) for Stage IV disease, but this differed by mucinous histology (moderate mucinous 6.2yr vs. poor mucinous 1.6yr, P=0.001; moderate nonmucinous 1.4yr, poor nonmucinous 2yr). 39 MAA pts underwent a complete CRS (30 moderate and 9 poor) with a median time to recurrence of 1.5yrs and median OS of 9.2yrs. Improved OS was seen for pts with a complete CRS compared to pts with an incomplete CRS, Pth edition use of a single mucinous high-grade category. The use of systemic chemotherapy appears to be a viable treatment option for these pts and a complete CRS is associated with improved OS.