Purpose: We evaluated the 7th edition of the American Joint Committee on Cancer (AJCC) staging classification in terms of overall survival (OS) in patients with PMP treated with cytoreductive surgery (CRS)/hyperthermic intraperitoneal chemotherapy (HIPEC).
Methods: A total of 208 PMP patients treated with CRS/HIPEC were identified from a prospective database. Patients with peritoneal mucinous carcinomatosis (PMCA) were retrospectively staged at time of diagnosis according to AJCC staging classification. Patients with disseminated peritoneal adenomucinosis (DPAM) were evaluated in a separate group.
Results: Median follow-up was 5.2 years. Of 208 patients, 124 had PMCA and 84 patients had DPAM. According to the AJCC staging classification 47 lymph node (LN) negative patients with well-differentiated PMCA, were classified as a stage IVA. 77 patients with either moderately or poorly differentiated PMCA irrespective of LN status, or well-differentiated PMCA with positive LN were classified as stage IVB. 84 patients with DPAM, constituted a separate group. OS of stage IVA and IVB patients was 100, 90, 67, and 91, 50, and 27 for 1, 3, and 5 years, respectively (p < 0.001). OS of DPAM patients was 96, 90, and 88 % for 1, 3, and 5 years, respectively (p = 0.025 comparing to IVA). PFS was estimated for IVA and IVB PMCA patients who were considered disease free after CRS/HIPEC and was 78, 52, and 43 % in the IVA patients and 65 %, 15 %, and 0 in the IVB group at 1, 3, and 5 years, respectively (p = 0.004). The adjusted HR for AJCC stages (IVA/IVB) was 3.7 (95 % confidence interval 2.0-6.7) (p < 0.001).
Conclusions: The 7th edition of the AJCC staging classification is a simple, reproducible, and valid classification for staging patients with PMCA undergoing CRS/HIPEC.