Optimal Surveillance Frequency After CRS/HIPEC for Appendiceal and Colorectal Neoplasms: A Multi-institutional Analysis of the US HIPEC Collaborative.

BACKGROUND: No guidelines exist for surveillance following cytoreductive surgery with hyperthermic intraperitoneal chemotherapy (CRS/HIPEC) for appendiceal and colorectal cancer. The primary objective was to define the optimal surveillance frequency after CRS/HIPEC. METHODS: The U.S. HIPEC Collaborative database (2000-2017) was reviewed for patients who underwent a CCR0/1 CRS/HIPEC for appendiceal or colorectal cancer. Radiologic surveillance frequency was divided into two categories: low-frequency surveillance (LFS) at q6-12mos or high-frequency surveillance (HFS) at q2-4mos. Primary outcome was overall survival (OS). RESULTS: Among 975 patients, the median age was 55 year, 41% were male: 31% had non-invasive appendiceal (n = 301), 45% invasive appendiceal (n = 435), and 24% colorectal cancer (CRC; n = 239). With a median follow-up time of 25 mos, the median time to recurrence was 12 mos. Despite less surveillance, LFS patients had no decrease in median OS (non-invasive appendiceal: 106 vs. 65 mos, p < 0.01; invasive appendiceal: 120 vs. 73 mos, p = 0.02; colorectal cancer [CRC]: 35 vs. 30 mos, p = 0.8). LFS patients had lower median PCI scores compared with HFS (non-invasive appendiceal: 10 vs. 19; invasive appendiceal: 10 vs. 14; CRC: 8 vs. 11; all p < 0.01). However, on multivariable analysis, accounting for PCI score, LFS was still not associated with decreased OS for any histologic type (non-invasive appendiceal: hazard ratio [HR]: 0.28, p = 0.1; invasive appendiceal: HR: 0.73, p = 0.42; CRC: HR: 1.14, p = 0.59). When estimating annual incident cases of CRS/HIPEC at 375 for non-invasive appendiceal, 375 invasive appendiceal and 4410 colorectal, LFS compared with HFS for the initial two post-operative years would potentially save $13-19 M/year to the U.S. healthcare system. CONCLUSIONS: Low-frequency surveillance after CRS/HIPEC for appendiceal or colorectal cancer is not associated with decreased survival, and when considering decreased costs, may optimize resource utilization.

Preoperative Risk Score for Predicting Incomplete Cytoreduction: A 12-Institution Study from the US HIPEC Collaborative.

BACKGROUND: For patients with peritoneal carcinomatosis undergoing cytoreductive surgery with heated intraperitoneal chemotherapy (CRS/HIPEC), incomplete cytoreduction (CCR2/3) confers morbidity without survival benefit. The aim of this study is to identify preoperative factors which predict CCR2/3. METHODS: All patients who underwent curative-intent CRS/HIPEC of low/high-grade appendiceal, colorectal, or peritoneal mesothelioma cancers in the 12-institution US HIPEC Collaborative from 2000 to 2017 were included (n = 2027). The primary aim is to create an incomplete-cytoreduction risk score (ICRS) to predict CCR2/3 CRS utilizing preoperative data. ICRS was created from a randomly selected cohort of 50% of patients (derivation cohort) and verified on the remaining patients (validation cohort). RESULTS: Within our derivation cohort (n = 998), histology was low-grade appendiceal neoplasms in 30%, high-grade appendiceal tumor in 41%, colorectal tumor in 22%, and peritoneal mesothelioma in 8%. CCR0/1 was achieved in 816 patients and CCR 2/3 in 116 patients. On multivariable analysis, preoperative factors associated with incomplete cytoreduction were male gender [odds ratio (OR) 3.4, p = 0.007], presence of ascites (OR 2.8, p = 0.028), cancer antigen (CA)-125 ≥ 40 U/mL (OR 3.4, p = 0.012), and carcinoembryonic antigen (CEA) ≥ 4.2 ng/mL (OR 3.2, p = 0.029). Each preoperative factor was assigned a score of 0 or 1 to form an ICRS from 0 to 4. Scores were grouped as zero (0), low (1-2), or high (3-4). Incidence of CCR2/3 progressively increased by risk group from 1.6% in zero to 13% in low and 39% in high. When ICRS was applied to the validation cohort (n = 1029), this relationship was maintained. CONCLUSION: The incomplete cytoreduction risk score incorporates preoperative factors to accurately stratify the risk of CCR2/3 resection in CRS/HIPEC. This score should not be used in isolation, however, to exclude patients from surgery.