Prediction of Early Recurrence Following CRS/HIPEC in Patients With Disseminated Appendiceal Cancer.

INTRODUCTION: In patients with disseminated appendiceal cancer (dAC) who underwent cytoreductive surgery (CRS) with hyperthermic intraperitoneal chemotherapy (HIPEC), characterizing and predicting those who will develop early recurrence could provide a framework for personalizing follow-up. This study aims to: (1) characterize patients with dAC that are at risk for recurrence within 2 y following of CRS ± HIPEC (early recurrence; ER), (2) utilize automated machine learning (AutoML) to predict at-risk patients, and (3) identifying factors that are influential for prediction. METHODS: A 12-institution cohort of patients with dAC treated with CRS ± HIPEC between 2000 and 2017 was used to train predictive models using H2O.ai's AutoML. Patients with early recurrence (ER) were compared to those who did not have recurrence or presented with recurrence after 2 y (control; C). However, 75% of the data was used for training and 25% for validation, and models were 5-fold cross-validated. RESULTS: A total of 949 patients were included, with 337 ER patients (35.5%). Patients with ER had higher markers of inflammation, worse disease burden with poor response, and received greater intraoperative fluids/blood products. The highest performing AutoML model was a Stacked Ensemble (area under the curve = 0.78, area under the curve precision recall = 0.66, positive predictive value = 85%, and negative predictive value = 63%). Prediction was influenced by blood markers, operative course, and factors associated with worse disease burden. CONCLUSIONS: In this multi-institutional cohort of dAC patients that underwent CRS ± HIPEC, AutoML performed well in predicting patients with ER. Variables suggestive of poor tumor biology were the most influential for prediction. Our work provides a framework for identifying patients with ER that might benefit from shorter interval surveillance early after surgery.

Patient and Caregiver Considerations and Priorities When Selecting Hospitals for Complex Cancer Care.

BACKGROUND: Healthcare policies have focused on centralizing care to high-volume centers in an effort to optimize patient outcomes; however, little is known about patients' and caregivers' considerations and selection process when selecting hospitals for care. We aim to explore how patients and caregivers select hospitals for complex cancer care and to develop a taxonomy for their selection considerations. METHODS: This was a qualitative study in which data were gathered from in-depth interviews conducted from March to November 2019 among patients with hepatopancreatobiliary cancers who were scheduled to undergo a pancreatectomy (n = 20) at a metropolitan, urban regional, or suburban medical center and their caregivers (n = 10). RESULTS: The interviews revealed six broad domains that characterized hospital selection considerations: hospital factors, team characteristics, travel distance to hospital, referral or recommendation, continuity of care, and insurance considerations. The identified domains were similar between participants seen at the metropolitan center and urban/suburban medical centers, with the following exceptions: participants receiving care specifically at the metropolitan center noted operative volume and access to specific services such as clinical trials in their hospital selection; participants receiving care at urban/suburban centers noted health insurance considerations and having access to existing medical records in their hospital selection. CONCLUSIONS: This study delineates the many considerations of patients and caregivers when selecting hospitals for complex cancer care. These identified domains should be incorporated into the development and implementation of centralization policies to help increase patient access to high-quality cancer care that is consistent with their priorities and needs.

A novel preoperative risk score to optimize patient selection for performing concomitant liver resection with cytoreductive surgery/HIPEC.

BACKGROUND: While parenchymal hepatic metastases were previously considered a contraindication to cytoreductive surgery (CRS) and heated intraperitoneal chemotherapy (HIPEC), liver resection (LR) is increasingly performed with CRS/HIPEC. METHODS: Patients from the US HIPEC Collaborative (2000-2017) with invasive appendiceal or colorectal adenocarcinoma undergoing primary, curative intent CRS/HIPEC with CC0-1 resection were included. LR was defined as a formal parenchymal resection. Primary endpoints were postoperative complications and overall survival (OS). RESULTS: A total of 658 patients were included. About 83 (15%) underwent LR of colorectal (58%) or invasive appendiceal (42%) metastases. LR patients had more complications (81% vs. 60%; p = .001), greater number of complications (2.3 vs. 1.5; p < .001) per patient and required more reoperations (22% vs. 11%; p = .007) and readmissions (39% vs. 25%; p = .014) than non-LR patients. LR patients had decreased OS (2-year OS 62% vs. 79%, p < .001), even when accounting for peritoneal carcinomatosis index and histology type. Preoperative factors associated with decreased OS on multivariable analysis in LR patients included age < 60 years (HR, 3.61; 95% CI, 1.10-11.81), colorectal histology (HR, 3.84; 95% CI, 1.69-12.65), and multiple liver tumors (HR, 3.45; 95% CI, 1.21-9.85) (all p < .05). When assigning one point for each factor, there was an incremental decrease in 2-year survival as the risk score increased from 0 to 3 (0: 100%; 1: 91%; 2: 58%; 3: 0%). CONCLUSIONS: As CRS/HIPEC + LR has become more common, we created a simple risk score to stratify patients considered for CRS/HIPEC + LR. These data aid in striking the balance between an increased perioperative complication profile with the potential for improvement in OS.

Elevated Maximum Core Body Temperature During Hyperthermic Intraperitoneal Chemoperfusion (HIPEC) is Associated with Increased Postoperative Complications.

BACKGROUND: Hyperthermia enhances the cytotoxicity of chemotherapeutic agents used during cytoreductive surgery (CRS) and hyperthermic intraperitoneal chemoperfusion (HIPEC). However, this may result in an elevated core body temperature (CBT), with unintended effects on surgical morbidity. This study evaluates the relationship of maximum CBT during CRS/HIPEC on postoperative outcomes. METHODS: A retrospective review of patients undergoing CRS/HIPEC from January 2011 to July 2017 was performed. Outcomes were stratified according to maximum CBT reached during HIPEC. Primary study endpoints were 30-day morbidity and 30-day complication severity. RESULTS: Overall, 135 consecutive CRS/HIPEC cases were reviewed; 36 (27%) had a maximum CBT ≥ 39.5 °C during the 90-min HIPEC. CBT ≥ 39.5 °C was associated with an increase in 30-day postoperative complications (58% vs. 34%, p = 0.01) and severe Clavien-Dindo grade III or higher complications (22% vs. 11%, p = 0.04). On multivariate analysis, the adjusted odds ratio of having any complication was 3.77 (95% confidence interval [CI] 1.56-9.14) and a Clavien-Dindo grade III or higher complication was 3.46 (95% CI 1.10-10.95) when maximum CBT reached 39.5 °C. Flow rates ≥ 2.35 L/min were associated with lower average CBT (p = 0.05) and improved peritoneal heating (p = 0.02). CONCLUSION: Maximum CBT ≥ 39.5 °C is associated with an increased risk of postoperative morbidity. Higher flow rates are associated with improved intraperitoneal heating, lower CBT, and may contribute to optimizing the therapeutic benefit of HIPEC.

CRS/HIPEC with Major Organ Resection in Peritoneal Mesothelioma Does not Impact Major Complications or Overall Survival: A Retrospective Cohort Study of the US HIPEC Collaborative.

INTRODUCTION: CRS/HIPEC is thought to confer a survival advantage for patients with malignant peritoneal mesothelioma (MPM). However, the impact of nonperitoneal organ resection is not clearly defined. We evaluated the impact of major organ resection (MOR) on postoperative outcomes and overall survival (OS). PATIENTS AND METHODS: The US HIPEC collaborative database (2000-2017) was reviewed for MPM patients who underwent CRS/HIPEC. MOR was defined as total or partial resection of diaphragm, stomach, spleen, pancreas, small bowel, colon, rectum, kidney, ureter, bladder, and/or uterus. MOR was categorized as 0, 1, or 2+ organs. RESULTS: A total of 174 patients were identified. Median PCI was 16 (3-39). The distribution of patients with MOR-0, MOR-1, and MOR-2+ was 94, 45, and 35 patients, respectively. MOR-1 and MOR-2+ groups had a higher frequency of any complication compared with MOR-0 (57.8%, 74.3%, and 48.9%, respectively, p = 0.035), but Clavien 3/4 complications were similar. Median length of stay was slightly higher in the MOR-1 and MOR-2+ groups (10 and 11 days) compared with the MOR-0 cohort (9 days, p = 0.005). Incomplete cytoreduction, ASA class 4, and male gender were associated with increased mortality on unadjusted analysis; however, their impact on OS was attenuated on multivariable analysis. MOR was not associated with OS based on these data (MOR-1: HR 1.67, 95% CI 0.59-4.74; MOR-2+ : HR 0.77, 95% CI 0.22-2.69). CONCLUSIONS: MOR was not associated with an increase in major complications or worse OS in patients undergoing CRS/HIPEC for MPM and should be considered, if necessary, to achieve complete cytoreduction for MPM patients.

Repeat Cytoreductive Surgery and Hyperthermic Intraperitoneal Chemotherapy Is Not Associated with Prohibitive Complications: Results of a Multiinstitutional Retrospective Study.

BACKGROUND: Cytoreductive surgery and hyperthermic intraperitoneal chemotherapy (CRS/HIPEC) is offered to select patients with peritoneal metastases. In instances of recurrence/progression, a repeat CRS/HIPEC may be considered. The perioperative morbidity and the potential oncologic benefits are not well described. PATIENTS AND METHODS: We performed a retrospective analysis of a multiinstitutional database to assess the perioperative outcomes following repeat CRS/HIPEC (repeat). Kaplan-Meier and Cox estimates were used to assess survival. RESULTS: In the entire cohort, 2157 patients were analyzed, with 158 (7.3%) in the repeat cohort. The rate of complete cytoreduction was 89.8% versus 83.0% in initial versus repeat groups. The overall incidence of major complications was similar (26.3% vs. 30.7%); however, reoperation was more common in the repeat group. Perioperative outcomes such as length of stay and nonhome discharge were not significantly different. For the entire cohort, 5-year overall survival (OS) was 56.0% in the initial group and 59.5% in the repeat group. In patients with only appendiceal cancer, we observed a 5-year OS of 64.0% in the initial group compared with 67.3% in the repeat cohort. For patients with appendiceal cancer who developed a recurrence/progression, median OS was 36 months in the no repeat operation group compared with 73 months for those that did. Multivariable regression demonstrated that completeness of cytoreduction and tumor grade were associated with OS, but repeat operation was not. CONCLUSIONS: Repeat CRS/HIPEC is not associated with prohibitive risk. Survival is possibly improved, and therefore, repeat operation should be considered in selected patients with recurrent or progressive disease.

Implications of Postoperative Complications for Survival After Cytoreductive Surgery and HIPEC: A Multi-Institutional Analysis of the US HIPEC Collaborative.

BACKGROUND: Postoperative complications (POCs) are associated with worse oncologic outcomes in various cancer histologies. The impact of POCs on the survival of patients with appendiceal or colorectal cancer after cytoreductive surgery (CRS) and heated intraperitoneal chemotherapy (HIPEC) is unknown. METHODS: The US HIPEC Collaborative (2000-2017) was reviewed for patients who underwent CCR0/1 CRS/HIPEC for appendiceal/colorectal cancer. The analysis was stratified by noninvasive appendiceal neoplasm versus invasive appendiceal/colorectal adenocarcinoma. The POCs were grouped into infectious, cardiopulmonary, thromboembolic, and intestinal dysmotility. The primary outcomes were overall survival (OS) and recurrence-free survival (RFS). RESULTS: Of the 1304 patients, 33% had noninvasive appendiceal neoplasm (n = 426), and 67% had invasive appendiceal/colorectal adenocarcinoma (n = 878). In the noninvasive appendiceal cohort, POCs were identified in 55% of the patients (n = 233). The 3-year OS and RFS did not differ between the patients who experienced a complication and those who did not (OS, 94% vs 94%, p = 0.26; RFS, 68% vs 60%, p = 0.15). In the invasive appendiceal/colorectal adenocarcinoma cohort, however, POCs (63%; n = 555) were associated with decreased 3-year OS (59% vs 74%; p < 0.001) and RFS (32% vs 42%; p < 0.001). Infectious POCs were the most common (35%; n = 196). In Multivariable analysis accounting for gender, peritoneal cancer index (PCI), and incomplete resection (CCR1), infectious POCs in particular were associated with decreased OS compared with no complication (hazard ratio [HR] 2.08; p < 0.01) or other types of complications (HR, 1.6; p < 0.01). Similarly, infectious POCs were independently associated with worse RFS (HR 1.61; p < 0.01). CONCLUSION: Postoperative complications are associated with decreased OS and RFS after CRS/HIPEC for invasive histology, but not for an indolent disease such as noninvasive appendiceal neoplasm, and this association is largely driven by infectious complications. The exact mechanism is unknown, but may be immunologic. Efforts must target best practices and standardized prevention strategies to minimize infectious postoperative complications.

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.

Predictors of Anastomotic Failure After Cytoreductive Surgery and Hyperthermic Intraperitoneal Chemotherapy: Does Technique Matter?

BACKGROUND: Anastomotic failure (AF) after cytoreductive surgery (CRS) with hyperthermic intraperitoneal chemotherapy (HIPEC) remains a dreaded complication. Whether specific factors, including anastomotic technique, are associated with AF is poorly understood. METHODS: Patients who underwent CRS-HIPEC including at least one bowel resection between 2000 and 2017 from 12 academic institutions were reviewed to determine factors associated with AF (anastomotic leak or enteric fistula). RESULTS: Among 1020 patients who met the inclusion criteria, the median age was 55 years, 43.9% were male, and the most common histology was appendiceal neoplasm (62.3%). The median Peritoneal Cancer Index was 14, and 93.2% of the patients underwent CC0/1 resection. Overall, 82 of the patients (8%) experienced an AF, whereas 938 (92.0%) did not. In the multivariable analysis, the factors associated with AF included male gender (odds ratio [OR], 2.2; p < 0.01), left-sided colorectal resection (OR 10.0; p = 0.03), and preoperative albumin (OR 1.8 per g/dL; p = 0.02).Technical factors such as method (stapled vs hand-sewn), timing of anastomosis, and chemotherapy regimen used were not associated with AF (all p > 0.05). Anastomotic failure was associated with longer hospital stay (23 vs 10 days; p < 0.01), higher complication rate (90% vs 59%; p < 0.01), higher reoperation rate (41% vs 9%; p < 0.01), more 30-day readmissions (59% vs 22%; p < 0.01), greater 30-day mortality (9% vs 1%; p < 0.01), and greater 90-day mortality (16% vs 8%; p = 0.02) as well as shorter median overall survival (25.6 vs 66.0 months; p < 0.01). CONCLUSIONS: Among patients undergoing CRS-HIPEC, AF is independently associated with postoperative morbidity and worse long-term outcomes. Because patient- and tumor-related, but not technical, factors are associated with AF, operative technique may be individualized based on patient considerations and surgeon preference.

Predictors of Non-home Discharge after Cytoreductive Surgery and Hyperthermic Intraperitoneal Chemotherapy.

BACKGROUND: Using a national database of cytoreductive surgery and hyperthermic intraperitoneal chemotherapy (CRS/HIPEC) recipients, we sought to determine risk factors for nonhome discharge (NHD) in a cohort of patients. METHODS: Patients undergoing CRS/HIPEC at any one of 12 participating sites between 2000 and 2017 were identified. Univariate analysis was used to compare the characteristics, operative variables, and postoperative complications of patients discharged home and patients with NHD. Multivariate logistic regression was used to identify independent risk factors of NHD. RESULTS: The cohort included 1593 patients, of which 70 (4.4%) had an NHD. The median [range] peritoneal cancer index in our cohort was 14 [0-39]. Significant predictors of NHD identified in our regression analysis were advanced age (odds ratio [OR], 1.09; 95% confidence interval [CI], 1.05-1.12; P < 0.001), an American Society of Anesthesiologists (ASA) score of 4 (OR, 2.87; 95% CI, 1.21-6.83; P = 0.017), appendiceal histology (OR, 3.14; 95% CI 1.57-6.28; P = 0.001), smoking history (OR, 3.22; 95% CI, 1.70-6.12; P < 0.001), postoperative total parenteral nutrition (OR, 3.14; 95% CI, 1.70-5.81; P < 0.001), respiratory complications (OR, 7.40; 95% CI, 3.36-16.31; P < 0.001), wound site infections (OR, 3.12; 95% CI, 1.58-6.17; P = 0.001), preoperative hemoglobin (OR, 0.81; 95% CI, 0.70-0.94; P = 0.006), and total number of complications (OR, 1.41; 95% CI, 1.16-1.73; P < 0.001). CONCLUSIONS: Early identification of patients at high risk for NHD after CRS/HIPEC is key for preoperative and postoperative counseling and resource allocation, as well as minimizing hospital-acquired conditions and associated health care costs.

Institutional variation in recovery after cytoreductive surgery and hyperthermic intraperitoneal chemotherapy: An opportunity for enhanced recovery pathways.

BACKGROUND: Variations in care have been demonstrated both within and among institutions in many clinical settings. By standardizing perioperative practices, Enhanced Recovery After Surgery (ERAS) pathways reduce variation in perioperative care. We sought to characterize the variation in cytoreductive surgery (CRS)/heated intraperitoneal chemotherapy (HIPEC) perioperative practices among experienced US medical centers. METHODS: Data from the US HIPEC Collaborative represents a retrospective multi-institutional cohort study of CRS and CRS/HIPEC procedures performed from 12 major academic institutions. Patient characteristics and perioperative practices were reported and compared. Institutional variation was analyzed using hierarchical mixed-effects linear (continuous outcomes) or logistic (binary outcomes) regression models. RESULTS: A total of 2372 operations were included. CRS/HIPEC was performed most commonly for appendiceal histologies (64.2%). The rate of complications (overall 56.3%, range: 31.8-70.9) and readmissions (overall 20.6%, range: 8.9-33.3) varied by institution (P < .001). Institution-level variation in perioperative practice patterns existed among measured ERAS pathway process/outcomes (P < .001). The percentages of variation with each process/outcome measure attributable solely to institutional practices ranged from 0.6% to 66.6%. CONCLUSIONS: Significant variation exists in the perioperative care of patients undergoing CRS/HIPEC at major US academic institutions. These findings provide a strong rationale for the investigation of best practices in CRS/HIPEC patients.

The impact of HIPEC vs. EPIC for the treatment of mucinous appendiceal carcinoma: a study from the US HIPEC collaborative.

INTRODUCTION: Mucinous appendiceal carcinoma is a rare malignancy that commonly spreads to the peritoneum leading to peritoneal metastases. Complete cytoreduction with perioperative intraperitoneal chemotherapy (PIC) is the mainstay of treatment, administered as either hyperthermic intra peritoneal chemotherapy (HIPEC) or early post-operative intraperitoneal chemotherapy (EPIC). Our goal was to assess the perioperative and long term survival outcomes associated with these two PIC methods. MATERIALS AND METHODS: Patients with mucinous appendiceal carcinoma were identified in the US HIPEC Collaborative database from 12 academic institutions. Patient demographics, clinical characteristics, and survival outcomes were compared among patients who underwent HIPEC vs. EPIC with inverse probability weighting (IPW) used for adjustment. RESULTS: Among 921 patients with mucinous appendiceal carcinoma, 9% underwent EPIC while 91% underwent HIPEC. There was no difference in Grade III-V complications between the two groups (18.5% for HIPEC vs. 15.0% for EPIC, p=.43) though patients who underwent HIPEC had higher rates of readmissions (21.2% vs. 8.8%, p<.01). Additionally, PIC method was not an independent predictor for overall survival (OS) or recurrence-free survival (RFS) after adjustment on multivariable analysis. CONCLUSIONS: Among patients with mucinous appendiceal carcinoma, both EPIC and HIPEC appear to be associated with similar perioperative and long-term outcomes.

Restrictive Intraoperative Fluid Therapy is Associated with Decreased Morbidity and Length of Stay Following Hyperthermic Intraperitoneal Chemoperfusion.

BACKGROUND: Recent data have demonstrated multiple benefits of intra- and postoperative fluid restriction in major abdominal surgery; however, data regarding the outcomes of fluid restriction in cytoreductive surgery and hyperthermic intraperitoneal chemoperfusion (CRS/HIPEC) are limited. This study evaluates the safety and short-term clinical outcomes of restricted intraoperative fluid therapy in CRS/HIPEC. METHODS: This was a single-institution, retrospective review of all CRS/HIPEC procedures performed at the University of Massachusetts Medical School between January 2009 and July 2017. Recorded variables included demographics, intraoperative factors, 60-day postoperative complications, and length of stay (LOS). Outcomes based on the use of intraoperative permissive fluid therapy (PFT) versus restrictive fluid therapy (RFT) were compared. RESULTS: Overall, 169 CRS/HIPEC cases were performed during the study period; 84 were managed with PFT and 85 were managed with RFT. No significant differences were identified in patient demographics. There was a decrease in intraoperative administration of crystalloid (8.0 vs. 4.4 L, p < 0.01), colloid (900 vs. 300 mL, p < 0.01), and blood transfusion (0.26 vs. 0.04 units, p < 0.01) in the RFT cohort. LOS was reduced from 11.5 to 9.7 days (p < 0.01) and the incidence of any 60-day complication decreased from 45 to 28% (p = 0.02) in the RFT group. The overall 90-day mortality rate was 0.6% (n = 1). Adjusted logistic regression demonstrated the odds of having a Clavien-Dindo grade III or higher complication was 0.31 (95% confidence interval 0.10-0.95) with RFT. CONCLUSION: Intraoperative RFT with standard anesthesia monitoring devices can be safely used in CRS/HIPEC and is associated with a decreased LOS and decreased rate of postoperative complications.

Primary Tumor Sidedness is Predictive of Survival in Colon Cancer Patients Treated with Cytoreductive Surgery With or Without Hyperthermic Intraperitoneal Chemotherapy: A US HIPEC Collaborative Study.

INTRODUCTION: The clinical relevance of primary tumor sidedness is not fully understood in colon cancer patients with peritoneal metastasis treated with cytoreductive surgery (CRS) and hyperthermic intraperitoneal chemotherapy (HIPEC). METHODS: This was a retrospective cohort study of a multi-institutional database of patients with peritoneal surface malignancy at 12 participating high-volume academic centers from the US HIPEC Collaborative. RESULTS: Overall, 336 patients with colon primary tumors who underwent curative-intent CRS with or without HIPEC were identified; 179 (53.3%) patients had right-sided primary tumors and 157 (46.7%) had left-sided primary tumors. Patients with right-sided tumors were more likely to be older, male, have higher Peritoneal Cancer Index (PCI), and have a perforated primary tumor, but were less likely to have extraperitoneal disease. Patients with complete cytoreduction (CC-0/1) had a median disease-free survival (DFS) of 11.5 months (95% confidence interval [CI] 7.6-15.3) versus 13.1 months (95% CI 9.5-16.8) [p = 0.158] and median overall survival (OS) of 30 months (95% CI 23.5-36.6) versus 45.4 months (95% CI 35.9-54.8) [p = 0.028] for right- and left-sided tumors; respectively. Multivariate analysis revealed that right-sided primary tumor was an independent predictor of worse DFS (hazard ratio [HR] 1.75, 95% CI 1.19-2.56; p =0.004) and OS (HR 1.72, 95% CI 1.09-2.73; p = 0.020). CONCLUSION: Right-sided primary tumor was an independent predictor of worse DFS and OS. Relevant clinicopathologic criteria, such as tumor sidedness and PCI, should be considered in patient selection for CRS with or without HIPEC, and guide stratification for clinical trials.

Development and Validation of an Explainable Machine Learning Model for Major Complications After Cytoreductive Surgery.

Importance: Cytoreductive surgery (CRS) is one of the most complex operations in surgical oncology with significant morbidity, and improved risk prediction tools are critically needed. Machine learning models can potentially overcome the limitations of traditional multiple logistic regression (MLR) models and provide accurate risk estimates. Objective: To develop and validate an explainable machine learning model for predicting major postoperative complications in patients undergoing CRS. Design, Setting, and Participants: This prognostic study used patient data from tertiary care hospitals with expertise in CRS included in the US Hyperthermic Intraperitoneal Chemotherapy Collaborative Database between 1998 and 2018. Information from 147 variables was extracted to predict the risk of a major complication. An ensemble-based machine learning (gradient-boosting) model was optimized on 80% of the sample with subsequent validation on a 20% holdout data set. The machine learning model was compared with traditional MLR models. The artificial intelligence SHAP (Shapley additive explanations) method was used for interpretation of patient- and cohort-level risk estimates and interactions to define novel surgical risk phenotypes. Data were analyzed between November 2019 and August 2021. Exposures: Cytoreductive surgery. Main Outcomes and Measures: Area under the receiver operating characteristics (AUROC); area under the precision recall curve (AUPRC). Results: Data from a total 2372 patients were included in model development (mean age, 55 years [range, 11-95 years]; 1366 [57.6%] women). The optimized machine learning model achieved high discrimination (AUROC: mean cross-validation, 0.75 [range, 0.73-0.81]; test, 0.74) and precision (AUPRC: mean cross-validation, 0.50 [range, 0.46-0.58]; test, 0.42). Compared with the optimized machine learning model, the published MLR model performed worse (test AUROC and AUPRC: 0.54 and 0.18, respectively). Higher volume of estimated blood loss, having pelvic peritonectomy, and longer operative time were the top 3 contributors to the high likelihood of major complications. SHAP dependence plots demonstrated insightful nonlinear interactive associations between predictors and major complications. For instance, high estimated blood loss (ie, above 500 mL) was only detrimental when operative time exceeded 9 hours. Unsupervised clustering of patients based on similarity of sources of risk allowed identification of 6 distinct surgical risk phenotypes. Conclusions and Relevance: In this prognostic study using data from patients undergoing CRS, an optimized machine learning model demonstrated a superior ability to predict individual- and cohort-level risk of major complications vs traditional methods. Using the SHAP method, 6 distinct surgical phenotypes were identified based on sources of risk of major complications.

A multi-institutional analysis of Textbook Outcomes among patients undergoing cytoreductive surgery for peritoneal surface malignancies.

BACKGROUND: While recent studies have introduced the composite measure of a textbook outcome (TO) for measuring postoperative outcomes, the incidence of a TO has not been characterized among patients undergoing cytoreductive surgery (CRS) for peritoneal surface malignancies (PSM). STUDY DESIGN: All patients who underwent CRS ± hyperthermic intraperitoneal chemotherapy (HIPEC) between 1999 and 2017 from 12 institutions were included. A TO was defined as the absence of any of the following criteria: completeness of cytoreduction >1, reoperation within 90-days, readmission within 90-days, mortality within 90-days, any grade ≥2 complication, hospital stay >75th percentile, and non-home discharge. RESULTS: Among 1904 patients who underwent CRS, only 30.9% achieved a TO while 69.1% failed to achieve a TO most commonly because of postoperative complications. On multivariable analysis, factors associated with achieving a TO were age <65 years (OR: 1.5), albumin ≥3.5 g/dl (OR: 5.7), receipt of HIPEC (OR: 4.5), PCI ≤14 (OR: 2.2), intravenous fluid volume ≤10,000 ml (OR: 2.1), blood loss ≤1000 ml (OR: 4.2) and operative time <7 h (OR: 1.9); while receipt of neoadjuvant therapy (OR: 0.7) and liver resection (OR: 0.4) were associated with not achieving a TO (all p < 0.05). TO was associated with improved overall survival (median 159 months vs 56 months, p < 0.01) even after controlling for confounders on Cox regression (hazard ratio: 2.5, p < 0.01). CONCLUSION: Among patients undergoing CRS ± HIPEC for PSM, failure to achieve a TO is common and independently associated with worse overall survival.

The Utility of Preoperative Tumor Markers in Peritoneal Carcinomatosis from Primary Appendiceal Adenocarcinoma: an Analysis from the US HIPEC Collaborative.

BACKGROUND: Prognostication based on preoperative clinical factors is lacking in patients undergoing cytoreductive surgery and hyperthermic intraperitoneal chemotherapy (CRS/HIPEC). This study aims to determine the value of preoperative tumor markers as predictors of progression-free survival (PFS) and overall survival (OS) for patients with peritoneal carcinomatosis from a primary mucinous adenocarcinoma of the appendix (MACA). METHODS: We queried the United States HIPEC Collaborative, a database of patients with peritoneal carcinomatosis treated with CRS/HIPEC at twelve institutions between 2000 and 2017, identifying 409 patients with MACA. Multivariate analysis was used to identify independent predictors of disease progression. Subgroup analysis was conducted to evaluate the impact of tumor grade on the predictive value of tumor markers. RESULTS: CA19-9 [HR 2.44, CI 1.2-3.4] emerged as an independent predictor of PFS while CEA [HR 4.98, CI 1.06-23.46] was independently predictive of OS (p <0.01). Tumor differentiation was the most potent predictor of both PFS (poorly differentiated vs well, [HR 4.5 CI 2.01-9.94]) and OS ([poorly differentiated vs well-differentiated: [HR 13.5, CI 3.16-57.78]), p <0.05. Among patients with combined CA19-9 elevation and poorly differentiated histology, 86% recurred within a year of CRS/HIPEC (p < 0.01). Similarly, the coexistence of CEA elevation and unfavorable histology led to the lowest survival rate at two years [36%, p < 0.01]. CA-125 was not predictive of PFS or OS. CONCLUSION: Elevated preoperative CA19-9 portends worse PFS, while elevated CEA predicts worse OS after CRS/HIPEC in patients with MACA. This study provides additional evidence that CA19-9 and CEA levels should be collected during standard preoperative bloodwork, while CA-125 can likely be omitted. Tumor differentiation, when added to preoperative tumor marker levels, provides powerful prognostic information. Prospective studies are required to confirm this association.

Impact of Neoadjuvant Chemotherapy on the Outcomes of Cytoreductive Surgery and Hyperthermic Intraperitoneal Chemotherapy for Colorectal Peritoneal Metastases: A Multi-Institutional Retrospective Review.

Cytoreductive surgery (CRS) with or without hyperthermic intraperitoneal chemotherapy (HIPEC) is associated with improved survival for patients with colorectal peritoneal metastases (CR-PM). However, the role of neoadjuvant chemotherapy (NAC) prior to CRS-HIPEC is poorly understood. A retrospective review of adult patients with CR-PM who underwent CRS+/-HIPEC from 2000-2017 was performed. Among 298 patients who underwent CRS+/-HIPEC, 196 (65.8%) received NAC while 102 (34.2%) underwent surgery first (SF). Patients who received NAC had lower peritoneal cancer index score (12.1 + 7.9 vs. 14.3 + 8.5, p = 0.034). There was no significant difference in grade III/IV complications (22.4% vs. 16.7%, p = 0.650), readmission (32.3% vs. 23.5%, p = 0.114), or 30-day mortality (1.5% vs. 2.9%, p = 0.411) between groups. NAC patients experienced longer overall survival (OS) (median 32.7 vs. 22.0 months, p = 0.044) but similar recurrence-free survival (RFS) (median 13.8 vs. 13.0 months, p = 0.456). After controlling for confounding factors, NAC was not independently associated with improved OS (OR 0.80) or RFS (OR 1.04). Among patients who underwent CRS+/-HIPEC for CR-PM, the use of NAC was associated with improved OS that did not persist on multivariable analysis. However, NAC prior to CRS+/-HIPEC was a safe and feasible strategy for CR-PM, which may aid in the appropriate selection of patients for aggressive cytoreductive surgery.