What is the Optimal Preoperative Imaging Modality for Assessing Peritoneal Cancer Index? An Analysis From the United States HIPEC Collaborative

Bland-Altman agreement analysis between CT predicted and surgical peritoneal cancer index in pseudomyxoma peritonei of appendiceal origin

Peritoneal cancer index (PCI) is the surgical variable most commonly used to quantify the extent of peritoneal metastases for pseudomyxoma peritonei (PMP) patients. The present study aimed to investigate the agreement between CT predicted and surgical PCI by the Bland-Altman method for PMP of appendiceal origin. A total of 167 PMP patients of appendiceal origin were included between 2016 and 2021. Bland-Altman analysis was performed for both total PCI and selected PCI (regions 2 + 9-12). After the Bland-Altman plot was drawn, the mean bias and its 95% limit of agreements (LoAs) was quantified. Besides, the correlation coefficients between CT-PCI and surgical PCI were also been calculated. The Bland-Altman plot showed the mean bias ± SD between total CT-PCI and surgical PCI as 0.431 ± 3.005, with the LoAs from - 5.459 to 6.321. There were nine points of difference in total PCI exceeded the 95% LoAs, with the rate of 5.39% (9/167). As for selected CT-PCI, Bland-Altman plot showed the mean bias ± SD between selected CT-PCI and surgical PCI as - 0.287 ± 1.955, with the LoAs from - 4.118 to 3.544. There were ten points of difference in selected PCI exceeded the 95% LoAs, with the rate of 5.99% (10/167). The Spearman's rank correlation coefficient between total CT-PCI and surgical PCI was 0.911, P < 0.001, as for selected CT-PCI and surgical PCI, the coefficient was 0.909, P < 0.001. Although there was a strong correlation for both total and selected CT-PCI with surgical PCI, however, the agreement is still not good in Bland-Altman analysis, which suggested that CT-PCI cannot predict surgical PCI accurately even in professional PMP treatment centers. In brief explanation, CT makes it difficult to distinguish the borderline between tumor tissue and mucus and to detect tumor lesions in the small intestine regions, which caused overestimation or underestimation by CT-PCI. In the future, a multiple linear regression model based on CT-PCI might accurately predict surgical PCI preoperatively.

FDG-PET/MRI for the preoperative diagnosis and staging of peritoneal carcinomatosis: a prospective multireader pilot study

PURPOSE

To assess the diagnostic performance of FDG-PET/MRI for the preoperative diagnosis and staging of peritoneal carcinomatosis (PC) using surgical Sugarbaker's PC index (PCI) as the reference in a multireader pilot study.

METHODS

Fourteen adult patients (M/F: 3/11, mean age: 57 ± 12 year) with PC were prospectively included in this single-center study. Patients underwent FDG-PET/MRI prior to surgery (mean delay: 14 d, range: 1-63 d). Images were reviewed independently by 2 abdominal radiologists and 2 nuclear medicine physicians. The radiologists assessed contrast-enhanced abdominal MR images, while the nuclear medicine physicians assessed PET images fused with T2-weighted images. The abdomen was divided in 13 regions, scored from 0 to 3. A hybrid FDG-PET/MRI radiological PCI was created by combining the study data. Radiological PCI was compared to the surgical PCI on a per-patient and per-region basis. Inter-reader agreement was evaluated.

RESULTS

Mean surgical PCI was 10 ± 8 (range: 0-24). Inter-reader agreement was almost perfect for all sets for radiologic PCI (Kappa: 0.81-0.98). PCI scores for all reading sets significantly correlated with the surgical PCI score (r range: 0.57-0.74, p range: < 0.001-0.003). Pooled per-patient sensitivity, specificity, and accuracy were 75%/50%/71.4% for MRI, 66.7%/50%/64.3% for FDG-PET, and 91.7%/50%/85.7% for FDG-PET/MRI, without significant difference (p value range 0.13-1). FDG-PET/MRI achieved 100% sensitivity and 100% specificity for a cutoff PCI of 20. Per-region sensitivity and accuracy were lower: 37%/61.8% for MRI, 17.8%/64.3% for FDG-PET, and 52.7%/60.4% for FDG-PET/MRI, with significantly higher sensitivity for FDG-PET/MRI. Per-region specificity was higher for FDG-PET (95%) compared to MRI (78.4%) and FDG-PET/MRI (66.5%).

CONCLUSION

FDG-PET/MRI achieved an excellent diagnostic accuracy per-patient and weaker performance per-region for detection of PC. The added value of PET/MRI compared to MRI and FDG-PET remains to be determined.

A single-center retrospective cohort study of perioperative systemic chemotherapy in diffuse malignant peritoneal mesothelioma

Background

Diffuse malignant peritoneal mesothelioma (DMPM) is a rare variant of malignant mesothelioma, representing 10–15% of malignant mesothelioma cases. The preferred therapeutic approach is cytoreductive surgery (CRS) accompanied by hyperthermic intraperitoneal chemotherapy (HIPEC); the role of systemic chemotherapy is not well established. While some limited retrospective studies report worse outcomes with neoadjuvant chemotherapy, our institution has favored the use of neoadjuvant chemotherapy for symptom relief and surgical optimization. The aim of our study was to assess the outcomes of patients receiving neoadjuvant chemotherapy, compared to those receiving adjuvant or no perioperative chemotherapy.

Patients and methods

We conducted a single-center retrospective cohort study of treatment-naïve, non-papillary DMPM patients seen at our institution between 1/1/2009 and 9/1/2019. We explored the effect of type of systemic therapy on clinical outcomes and estimated median overall survival (mOS) using Kaplan-Meier curves. Hazard ratios (HR) calculated by Cox proportional hazard model were used to estimate effect of the exposures on overall survival.

Results

47 patients were identified with DMPM (median age at diagnosis 61.2 years, 76.6% epithelioid histology, 74.5% white race, 55.3% known asbestos exposure). CRS was performed in 53.2% of patients (25/47); 76.0% of surgical patients received HIPEC (19/25). The majority received systemic chemotherapy (37/47, 78.7%); among patients receiving both CRS and chemotherapy, neoadjuvant chemotherapy was more common than adjuvant chemotherapy (12 neoadjuvant, 8 adjuvant). Overall mOS was 84.1 months. Among neoadjuvant patients, 10/12 underwent surgery, and 2 were lost to follow-up; the majority (9/10) had clinically stable or improved disease during the pre-operative period. There were numerical more issues with chemotherapy with the adjuvant patients (4/8: 2 switches in platinum agent, 2 patients stopped therapy) than with the neoadjuvant patients (2/10: 1 switch in platinum agent, 1 delay due to peri-procedural symptoms). Neoadjuvant chemotherapy was not associated with worse mOS compared to adjuvant chemotherapy (mOS NR vs 95.1 mo, HR 0.89, 95% CI 0.18–4.5, p = 0.89).

Conclusions

When used preferentially, the use of neoadjuvant chemotherapy in DMPM patients was not associated with worse outcomes compared to adjuvant chemotherapy. It was well-tolerated and did not prevent surgical intervention.

Current Trends in Cytoreductive Surgery (CRS) and Hyperthermic Intraperitoneal Chemotherapy (HIPEC) for Peritoneal Disease from Appendiceal and Colorectal Malignancies

Peritoneal carcinomatosis (PC) is a poor prognostic factor for all malignancies. This extent of metastatic disease progression remains difficult to treat with systemic therapies due to poor peritoneal vascularization resulting in limited drug delivery and penetration into tissues. Cytoreductive surgery (CRS) and hyperthermic intraperitoneal chemotherapy (HIPEC) are surgical interventions that directly target peritoneal tumors and have improved outcomes for PC resulting from appendiceal and colorectal cancer (CRC). Despite these radical therapies, long-term survival remains infrequent, and recurrence is common. The reasons for these outcomes are multifactorial and signal the need for the continued development of novel therapeutics, techniques, and approaches to improve outcomes for these patients. Here, we review landmark historical studies that serve as the foundation for current recommendations, recent discoveries, clinical trials, active research, and areas of future interest in CRS/HIPEC to treat PC originating from appendiceal and colorectal malignancies.

The role of imaging in diagnosis and management of malignant peritoneal mesothelioma: a systematic review

PURPOSE

Imaging of the peritoneum and related pathology is a challenge. Among peritoneal diseases, malignant peritoneal mesothelioma (MPeM) is an uncommon tumor with poor prognosis. To date, there are no specific guidelines or imaging protocols dedicated for the peritoneum and MPeM. The objective of this study was to analyze the literature describing imaging modalities used for MPeM to determine their relative clinical efficacy and review commonly reported imaging features of MPeM to promote standardized reporting.

METHODS

We performed a systematic review of original research articles discussing imaging modalities in MPeM from 1999 to 2020. Effectiveness measures and common findings were compared across imaging modalities.

RESULTS

Among 582 studies analyzed, the most-used imaging modality was CT (54.3%). In the differentiation of MPeM from peritoneal carcinomatosis, one study found CT had a diagnostic sensitivity of 53%, specificity of 100%, and accuracy of 68%. Two studies found fluorodeoxyglucose positron emission tomography (FDG-PET) had sensitivity of 86-92%, specificity of 83-89%, and accuracy of 87-89%. Another study found magnetic resonance imaging (MRI) was the best predictor of the peritoneal carcinomatosis index. Characteristics shown to best differentiate MPeM from other diseases included ascites, peritoneal thickening, mesenteric thickening, pleural plaques, maximum tumor dimension, and number of masses.

CONCLUSION

Most published MPeM imaging studies utilized CT. PET/CT or MRI appear promising, and future studies should compare effectiveness of these modalities. MPeM imaging reports should highlight ascites, number of and maximum tumor dimension, peritoneal/mesenteric thickening, and associated pleural plaques, allowing for better aggregation of MPeM imaging data across studies.

Utility of hyperthermic intraperitoneal chemotherapy in cases of incomplete cytoreductive surgery

INTRODUCTION

Hyperthermic intraperitoneal chemotherapy (HIPEC) during cytoreductive surgery (CRS) is typically reserved for a complete or optimal cytoreduction. There is the potential for therapeutic effect of HIPEC with an incomplete cytoreduction, particularly for near optimal cytoreductions.

METHODS

Retrospective review of incomplete cytoreductions (R2b, R2c) for appendiceal and colorectal primaries. Primary endpoints were overall survival (OS) and progression-free survival (PFS). Subgroup analysis for primary etiology and specific cytoreductive score.

RESULTS

A total of 121 cases of incomplete CRS, 74 CRS alone, and 47 CRS-HIPEC. For the entire study group there was a survival benefit with HIPEC. OS and PFS were 2.3 versus 1.4 (p = 0.001) and 1.6 versus 0.7 (p < 0.0001) respectively for cases with and without HIPEC. Subgroup analysis of appendiceal neoplasms, 43 CRS-HIPEC and 50 CRS alone, found HIPEC benefit persisted; OS and PFS were 2.4 versus 1.5 (p = 0.016) and 1.7 versus 0.8 (p < 0.0001), respectively for cases with and without HIPEC. Benefit most pronounced in low-grade cases with doubling of the OS and PFS (p = 0.004). With colorectal primary cases, 10 CRS-HIPEC and 18 CRS alone, no difference in OS and PFS. When stratifying out by cytoreduction scores, R2b and R2c, HIPEC only provided a benefit for R2b cases; OS and PFS for R2b cases were 2.28 versus 1.01 (p = 0.011) and 1.67 versus 0.75 (p = 0.001), respectively for cases with and without HIPEC.

CONCLUSION

HIPEC has utility for incomplete cytoreductions with appendiceal neoplasms, greatest effect with low-grade appendiceal neoplasms. HIPEC is only beneficial for near optimal cytoreductions (R2b).

Adding Value of MRI over CT in Predicting Peritoneal Cancer Index and Completeness of Cytoreduction

BACKGROUND

This study aimed to investigate the adding value of MRI over CT for preoperative cytoreductive surgery with hyperthermic intraperitoneal chemotherapies (CRS/HIPEC).

METHODS

Imaging and intraoperative peritoneal cancer index (PCI) were calculated in 62 patients with peritoneal metastasis. Predictive models for the completeness of cytoreductive score using PCI data were established using decision tree algorithms.

RESULTS

In gastric cancer patients, a large discrepancy and poor agreement was appreciated between CT and surgical PCI, and a nonsignificant difference was noted between MRI and surgical PCI. In colon cancer patients, a better agreement and higher correlation with a smaller error was observed in PCI score using MRI than in that using CT. However, the addition of MRI to CT was limited for appendiceal and ovarian cancer patients. For predicting incomplete cytoreduction, CT models yielded inadequate accuracy while MRI models were more accurate with fair discrimination ability.

CONCLUSIONS

CT was suitable for estimating PCI and surgery outcome in appendiceal and ovarian cancer patients, while further MRI in addition to CT was recommended for colon and gastric cancer patients. However, for classifying patients with peritoneal carcinomatosis into complete and incomplete cytoreduction, MRI was more effective than CT.

Assessment of peritoneal metastases with DW-MRI, CT, and FDG PET/CT before cytoreductive surgery for advanced stage epithelial ovarian cancer

BACKGROUND

Preoperative assessment of peritoneal metastases is an important factor for treatment planning and selection of candidates for cytoreductive surgery (CRS) in primary advanced stage (FIGO stages III-IV) epithelial ovarian cancer (EOC). The primary aim was to evaluate the efficacy of DW-MRI, CT, and FDG PET/CT used for preoperative assessment of peritoneal cancer index (PCI).

MATERIAL AND METHODS

In this prospective observational cohort study, 50 advanced stage EOC patients were examined with DW-MRI and FDG PET/CT with contrast enhanced CT as part of the diagnostic program. All patients were deemed amenable for upfront CRS. Imaging PCI was determined for DW-MRI, CT, and FDG PET/CT by separate readers blinded to the surgical findings. The primary outcome was agreement between the imaging PCI and PCI determined at surgical exploration (the reference standard) evaluated with Bland-Altman statistics.

RESULTS

The median surgical PCI was 18 (range: 3-32). For all three imaging modalities, the imaging PCI most often underestimated the surgical PCI. The mean differences between the surgical PCI and the imaging PCI were 4.2 (95% CI: 2.6-5.8) for CT, 4.4 (95% CI: 2.9-5.8) for DW-MRI, and 5.3 (95% CI: 3.6-7.0) for FDG PET/CT, and no overall statistically significant differences were found between the imaging modalities (DW-MRI - CT, p = 0.83; DW-MRI - FDG PET/CT, p = 0.24; CT - FDG PET/CT, p = 0.06).

CONCLUSION

Neither DW-MRI nor CT nor FDG PET/CT was superior in preoperative assessment of the surgical PCI in patients scheduled for upfront CRS for advanced stage EOC.

Imaging spectrum of mesenteric masses

Mesenteries are extensions of the visceral and parietal peritoneum consisting of fat, vessels, nerves, and lymphatics. Mesenteric masses have a wide differential diagnosis with neoplastic, infectious, or inflammatory etiologies and can either be solid or cystic. Imaging features are critical for the diagnosis. We review the epidemiology, imaging spectrum, and differentiating features and treatment of mesenteric masses.

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.

Concurrent hysterectomy and bilateral salpingo-oophorectomy during cytoreductive surgery and hyperthermic intraperitoneal chemotherapy for non-gynecologic cancers

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Hysterectomy and bilateral salpingo-oophorectomy in non-gynecologic HIPEC cases improves cytoreductive surgery efforts.

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Metastatic lesions often involve the pelvic organs on final pathology despite pre-operative and intraoperative findings.

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Hysterectomy and bilateral salpingo-oophorectomy adds minimal morbidity to the procedure.

Hyperthermic intraperitoneal chemotherapy (HIPEC) is a key component of treatment in non-gynecologic peritoneal surface malignancies. As many as 10–15% of patients with a gastrointestinal primary malignancy will present with carcinomatosis. Maximal cytoreductive surgery directly affects the prognosis of patients. The routine inclusion of hysterectomy with bilateral salpingo-oophorectomy during these procedures optimizes cytoreduction despite negative pre-operative imaging and findings at the time of surgery. In this case series, we review twenty non-gynecologic cancer patients who underwent cytoreductive surgery with concurrent hysterectomy and bilateral salpingo-oophorectomy and HIPEC at our institution.

The Intersection of Age and Tumor Biology with Postoperative Outcomes in Patients After Cytoreductive Surgery and HIPEC

BACKGROUND

Patient age is a significant factor in preoperative selection for major abdominal surgery. The association of age, tumor biology, and postoperative outcomes in patients undergoing cytoreductive surgery (CRS) and hyperthermic intraperitoneal chemotherapy (HIPEC) remains ill-defined.

METHODS

Retrospective analysis was performed for patients who underwent a CCR0/1 CRS/HIPEC from the US HIPEC Collaborative Database (2000-2017). Age was categorized into < 65 or ≥ 65 years. Primary outcome was postoperative major complications. Secondary outcomes were non-home discharge (NHD) and readmission. Analysis was stratified by disease histology: non-invasive (appendiceal LAMN/HAMN), and invasive (appendiceal/colorectal adenocarcinoma).

RESULTS

Of 1090 patients identified, 22% were ≥ 65 (n = 240), 59% were female (n = 646), 25% had non-invasive (n = 276) and 51% had invasive (n = 555) histology. Median PCI was 13 (IQR 7-20). Patients ≥ 65 had a higher rate of major complications (37 vs 26%, p = 0.02), NHD (12 vs 5%, p < 0.01), and readmission (28 vs 22%, p = 0.05), compared to those < 65. For non-invasive histology, age ≥ 65 was not associated with major complications or NHD on multivariable analysis. For invasive histology, when accounting for PCI and CCR, age ≥ 65 was associated with major complications (OR 2.04, 95% CI 1.16-3.59, p = 0.01). When accounting for major complications, age ≥ 65 was associated with NHD (OR 2.54, 95% CI 1.08-5.98, p = 0.03). Age ≥ 65 was not predictive of readmission for any histology when accounting for major complications.

CONCLUSIONS

Age ≥ 65 years is an independent predictor for postoperative major complications and non-home discharge for invasive histology, but not non-invasive histology. These data inform preoperative counseling, risk stratification, and early discharge planning.