Mucinous tumor of the appendix with limited peritoneal spread: is there a role for expectant observation?

Background: Cytoreductive surgery (CRS) and hyperthermic intraperitoneal chemotherapy (HIPEC) is now the standard management for mucinous tumors of appendiceal origin at many centers. We examined the role of expectant observation (EO) in patients who had undergone an initial resection at the time of referral to our center and who had limited residual disease.

Methods: We performed a retrospective review of patients referred to Mount Sinai/Princess Margaret Hospitals, Toronto, for consideration of surgical management of peritoneal malignancy between January 1998 and December 2009. One hundred and three patients with primary mucinous appendiceal malignancy were identified. EO, consisting of regularly scheduled imaging and clinical review, was selected for asymptomatic patients with low-grade tumor and no/limited disease on imaging. Overall survival (OS) and progression-free survival (PFS) were determined.

Results: Management consisted of supportive care in 7 patients, systemic chemotherapy in 7, referral for CRS with HIPEC in 8, CRS without HIPEC at our center in 51, and EO in 30. In the CRS group, 5-year OS was 74 % and PFS was 56 %; both OS and PFS were predicted by extent of residual disease after cytoreduction (p = 0.014 and p = 0.011, respectively). In the EO group, 5-year OS and PFS were 95 and 82 %, respectively. Two patients in the EO group subsequently underwent CRS for progression on imaging.

Conclusions: In well-selected patients who have undergone initial resection for low-grade mucinous tumor of the appendix with limited peritoneal spread, a formal program of observation can result in excellent 5-year OS and PFS. Longer-term follow-up will help define the benefits and risks of this approach.