Surgical Peritoneal Cancer Index Research Articles

The importance of integrating diagnostic modalities in patient selection for CRS-HIPEC in colorectal peritoneal metastases.

Despite thorough preoperative work-up for cytoreductive surgery and hyperthermic intraperitoneal chemotherapy (CRS-HIPEC), so called open-close (OC) procedures as a result of irresectable disease remain common. Currently, diagnostic laparoscopy (DLS) is considered the gold standard, and consequently overrules the results of computed tomography (CT) scans; however, certain regions of the abdomen are difficult to assess and postoperative adhesion formation may further compromise staging during DLS. To determine whether better clinical assessment could be achieved by combining the results of DLS and preoperative CT scans during a multidisciplinary team (MDT) meeting. All patients who were eligible for CRS-HIPEC after DLS, but eventually underwent an OC procedure between 2010 and 2018 were selected. Radiological reassessment of CT scans was performed and combined with assessment of the DLS during a MDT meeting. The MDT was blinded for the outcome of the procedure (OC vs. CRS-HIPEC). The majority of the OC procedures (69%) was correctly predicted by the MDT. In most patients (88%), this conclusion was based on the combination of the radiological and surgical peritoneal cancer index (PCI). CT was particularly accurate for detection of larger tumor deposits in the abdominal regions, as 84%-86% was detected. Assessment of lesions in the small bowel regions is troublesome; 72% of lesions are missed on the preoperative CT scan. A combination of radiological and surgical assessment of the PCI may lead to improved preoperative patient selection for CRS-HIPEC.

Perioperative outcomes and platinum resistant recurrence in patients undergoing systematic, protocol-based, total parietal peritonectomy during interval cytoreductive surgery for advanced ovarian cancer: results of the TORPEDO study.

The TORPEDO (CTRI/2018/12/016789) is the single-arm, prospective, interventional study evaluating the role of a total parietal peritonectomy (TPP) in patients undergoing interval cytoreductive surgery (iCRS). In this manuscript, we report the perioperative outcomes and platinum resistant recurrence (PRR) in 218 patients enrolled in the study. A TPP was performed in all patients undergoing iCRS irrespective of the residual disease extent. hyperthermic intraperitoneal chemotherapy (HIPEC) was performed as per the clinician's discretion with 75 mg/m² of cisplatin. Maintenance therapy was also used at the discretion of the treating clinicians. From 9th December 2018 to 31st July 2022 (recruitment complete), 218 patients were enrolled at 4 medical centers in India. The median surgical peritoneal cancer index was 14 and a complete gross resection was achieved in 95.8%. HIPEC was performed in 130 (59.6%) patients. The 90-day major morbidity was 17.4% and 2.7% patients died within 90 days of surgery. Adjuvant chemotherapy was delayed beyond 6 weeks in 7.3%. At a median follow-up of 19 months (95% confidence interval [CI]=15.9-35 months), 101 (46.3%) recurrences and 19 (8.7%) deaths had occurred. The median progression-free survival was 22 months (95% CI=17-35 months) and the median overall survival (OS) not reached. Platinum resistant recurrence was observed in 6.4%. The projected 3-year OS was 81.5% and in 80 patients treated before may 2020, it was 77.5%. The morbidity and mortality of TPP with or without HIPEC performed during iCRS is acceptable. The incidence was of PRR is low. Early survival results are encouraging and warrant conduction of a randomized controlled trial comparing TPP with conventional surgery.

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.

68Ga]Ga-FAPI-04 PET/CT in the evaluation of epithelial ovarian cancer: comparison with [18F]F-FDG PET/CT.

To compare the efficacy of [68Ga]Ga-FAPI-04 PET/CT in primary or recurrent tumors and metastatic lesions of epithelial ovarian cancer (EOC) with that of fluorine-18 fluorodeoxyglucose ([18F]F-FDG) PET/CT. Forty-nine patients (median age, 57 years; IQR, 51-66 years) with histologically proven primary or relapsed EOC were enrolled. Participants underwent [18F]F-FDG and [68Ga]Ga-FAPI-04 PET/CT. The detection rate, diagnostic accuracy, semiquantitative parameters, tumor staging, and clinical management of the tracers were compared. The diagnostic performance of [18F]F-FDG and [68Ga]Ga-FAPI-04 PET/CT was evaluated and compared using surgical pathology. Differences between methods regarding the peritoneal cancer index (PCI) using preoperative imaging, surgical PCI, and tumor markers (CA125, HE4) were also assessed regarding peritoneal metastases. Among the 49 patients, 28 had primary EOC; 21 had relapsed EOC. [68Ga]Ga-FAPI-04 PET/CT outperformed [18F]F-FDG PET/CT in detecting peritoneal metastases (96.8% vs. 83.0%; p < 0.001), retroperitoneal (99.5% vs. 91.4%; p < 0.001), and supradiaphragmatic lymph node metastases (100% vs. 80.4%; p < 0.001). Compared with [18F]F-FDG, [68Ga]Ga-FAPI-04 showed higher SUVmax for peritoneal metastases (17.31 vs. 13.68; p = 0.026) and retroperitoneal (8.72 vs. 6.56; p < 0.001) and supradiaphragmatic lymph node metastases (6.39 vs. 4.20; p < 0.001). Moreover, [68Ga]Ga-FAPI-04 PET/CT showed higher sensitivity compared with [18F]F-FDG PET/CT for detecting metastatic lymph nodes (80.6% vs. 61.3%; p = 0.031) and peritoneal metastases (97.5% vs. 75.9%; p < 0.001), using surgical pathology as the gold standard. Compared with [18F]F-FDG PET/CT, [68Ga]Ga-FAPI-04 PET/CT led to an upgrade in 14.3% and 33.3% of treatment-naive and relapse participants, resulting in management changes in 10.7% and 19.0% of the patients, respectively. The median PCIFAPI scores were significantly higher than PCIFDG (15 vs. 11; p < 0.001) and positively correlated with CA125 and HE4 levels and surgical PCI. [68Ga]Ga-FAPI-04 PET/CT achieved higher sensitivity than [18F]F-FDG PET/CT in the detection and diagnosis of lymph node and peritoneal metastases, suggesting advantages regarding the preoperative staging of patients with EOC and, thereby, improving treatment decision-making. NCT05034146. Registered February 23, 2021.

A CT-Based Radiomics Model for Evaluating Peritoneal Cancer Index in Peritoneal Metastasis Cases: A Preliminary Study

The present work aimed to develop and validate a radiomics model for evaluating peritoneal cancer index (PCI) in peritoneal metastasis (PM) cases based on preoperative CT scans. Pathologically confirmed pancreatic, colon, rectal, and gastric cancer cases with PM administered exploratory laparotomy in 2 different cohorts were retrospectively analyzed. Surgical PCIs (sPCIs) were confirmed by the surgery team, and CT-PCI scores were assessed by radiologists. Totally 63 and 27 cases in cohort 1 were assigned to the training and test groups, respectively. Then, 73 cases in cohort 2 were enrolled as an external validation set. Radiomics features were derived from the portal venous phase of preoperative abdominopelvic CT scans. Nineteen optimal features related to sPCI were finally selected. Support vector machine (SVM) was adopted for radiomics model generation. The associations of CT-PCI, radiomics PCI and sPCI were analyzed. The performances in distinguishing between low-sPCI (≤ 20) and high-sPCI (> 20) cases were also assessed by receiver operating characteristic (ROC) curve analysis and decision curve analysis (DCA). Both CT-PCI and radiomics PCI scores had positive associations with sPCI. The radiomics approach had higher agreement for detecting sPCI than CT-PCI. In addition, the radiomics model had enhanced diagnostic performance than CT-PCI (AUCs were 0.894, 0.822 and 0.810 in training, test and validation sets, respectively, vs 0.749, 0.678 and 0.693, respectively). The net reclassification index was 0.266. The usefulness of the proposed model was confirmed by DCA in an external validation set. The present pilot study showed that the radiomics model based on preoperative abdominopelvic CT has increased agreement and diagnostic performance in detecting sPCI than CT-PCI in patients with PM, which could be used to optimize individualized treatment strategies.

Performances of 18F-FDOPA PET/CT in the Preoperative Evaluation of the Peritoneal Cancer Index in Small Intestine Neuroendocrine Tumors.

Peritoneal carcinomatosis (PC) concerns up to 30% of patients with a neuroendocrine tumor (NET), especially of the small intestine. Aggressive management of carcinomatosis seems to be justified, especially with regard to possible mechanical complications. 18F-FDOPA PET/CT is known to be the most sensitive imaging modality for the detection of small bowel NET metastases, yet its performance in the detection of PC is not well studied. The main objective of our study is to evaluate the performances of preoperative 18F-FDOPA PET/CT in the prediction of surgical peritoneal cancer index. All patients referred to our center for an 18F-FDOPA PET/CT from October 2017 to January 2021 were retrospectively screened. Images were analyzed by a blinded nuclear medicine physician, and peritoneal abnormalities were reported to comply with the surgical peritoneal cancer index standard. Per patient analysis and per region analysis were then conducted. Thirty-three patients were included; 6 patients (35 regions) presented a peritoneal carcinosis. Peritoneal Carcinomatosis Index (PCI) estimated on 18F-FDOPA PET/CT was significantly and strongly correlated to surgical PCI (r = 0.96, P < 0.001). Patient-based sensitivity, specificity, negative predictive value, and positive predictive value for 18F-FDOPA PET/CT were 100%, 93%, 100%, and 75%, respectively. The agreement between 18F-FDOPA and surgery regarding PC was excellent (Cohen κ = 0.82 on per patient analysis, 0.74 on per region analysis). A preoperative estimation of PCI is achievable based on 18F-FDOPA PET/CT for small intestine NET and could allow to optimize surgical procedures and patient selection.

Diagnostic performance of MRI for staging peritoneal metastases in patients with colorectal cancer after neoadjuvant chemotherapy

IntroductionMRI improves the selection of patients with colorectal cancer (CRC) and peritoneal metastases (PM) for cytoreductive surgery by accurately assessing the extent of PM reflected as the peritoneal cancer index (PCI). The performance of MRI after neoadjuvant chemotherapy (NACT) for staging PM, however is unknown. The purpose of this study was to determine whether MRI could also accurately determine the PCI after NACT. Materials and MethodsThis was a single-centre, retrospective study of patients with PM from CRC or appendiceal origin who received NACT followed by diffusion-weighted (DW)-MRI and surgery from January 2016 to February 2021. Two radiologists assessed the PCI on restaging DW-MRI (mriPCI). The reference standard was the surgical PCI (sPCI). The main outcome was the diagnostic performance of restaging DW-MRI in predicting whether patients were eligible for cytoreductive surgery (CRS) and hyperthermic intraperitoneal chemotherapy (HIPEC), defined as a PCI < 21 with metastases on resectable locations. If CRS-HIPEC was performed, the resected peritoneal lesions were assessed and correlated with the final pathological PCI (pPCI). ResultsThirty-three patients were included. Both readers correctly detected all 23 patients with resectable disease. Eight out of ten patients with unresectable disease during staging surgery were detected by both readers with MRI. The intraclass correlation (ICC) between both readers was excellent (0⋅87 (95% CI: 0⋅75 to 0⋅93)). The ICC between pPCI and mriPCI was 0⋅74 (0⋅49-0⋅88) and 0⋅82 (0⋅66-0⋅91) for the 2 readers. Surgical PCI (sPCI) had a similar correlation as mriPCI with pPCI 0⋅82 (0⋅62- 0⋅92)) and 0⋅81 (0⋅57-0⋅92)). ConclusionDW-MRI is a promising tool to reassess the peritoneal cancer index after neoadjuvant chemotherapy.

Association between High Diffusion-Weighted Imaging-Derived Functional Tumor Burden of Peritoneal Carcinomatosis and Overall Survival in Patients with Advanced Ovarian Carcinoma.

ObjectiveTo investigate the association between functional tumor burden of peritoneal carcinomatosis (PC) derived from diffusion-weighted imaging (DWI) and overall survival in patients with advanced ovarian carcinoma (OC).Materials and MethodsThis prospective study was approved by the local research ethics committee, and informed consent was obtained. Fifty patients (mean age ± standard deviation, 57 ± 12 years) with stage III–IV OC scheduled for primary or interval debulking surgery (IDS) were recruited between June 2016 and December 2021. DWI (b values: 0, 400, and 800 s/mm2) was acquired with a 16-channel phased-array torso coil. The functional PC burden on DWI was derived based on K-means clustering to discard fat, air, and normal tissue. A score similar to the surgical peritoneal cancer index was assigned to each abdominopelvic region, with additional scores assigned to the involvement of critical sites, denoted as the functional peritoneal cancer index (fPCI). The apparent diffusion coefficient (ADC) of the largest lesion was calculated. Patients were dichotomized by immediate surgical outcome into high- and low-risk groups (with and without residual disease, respectively) with subsequent survival analysis using the Kaplan-Meier curve and log-rank test. Multivariable Cox proportional hazards regression was used to evaluate the association between DWI-derived results and overall survival.ResultsFifteen (30.0%) patients underwent primary debulking surgery, and 35 (70.0%) patients received neoadjuvant chemotherapy followed by IDS. Complete tumor debulking was achieved in 32 patients. Patients with residual disease after debulking surgery had reduced overall survival (p = 0.043). The fPCI/ADC was negatively associated with overall survival when accounted for clinicopathological information with a hazard ratio of 1.254 for high fPCI/ADC (95% confidence interval, 1.007–1.560; p = 0.043).ConclusionA high DWI-derived functional tumor burden was associated with decreased overall survival in patients with advanced OC.

Validation of 18F-FDG PET/MRI and diffusion-weighted MRI for estimating the extent of peritoneal carcinomatosis in ovarian and endometrial cancer -a pilot study

BackgroundThe extent of peritoneal carcinomatosis is difficult to estimate preoperatively, but a valid measure would be important in identifying operable patients.The present study set out to validate the usefulness of integrated 18F-FDG PET/MRI, in comparison with diffusion-weighted MRI (DW-MRI), for estimation of the extent of peritoneal carcinomatosis in patients with gynaecological cancer.MethodsWhole-body PET/MRI was performed on 34 patients with presumed carcinomatosis of gynaecological origin, all scheduled for surgery. Two radiologists evaluated the peritoneal cancer index (PCI) on PET/MRI and DW-MRI scans in consensus. The surgeon estimated PCI intraoperatively, which was used as the gold standard.ResultsMedian total PCI for PET/MRI (21.5) was closer to surgical PCI (24.5) (p = 0.6), than DW-MRI (median PCI 20.0, p = 0.007). However, both methods were highly correlated with the surgical PCI (PET/MRI: β = 0.94 p < 0.01, DW-MRI: β = 0.86, p < 0.01). PET/MRI was more accurate (p = 0.3) than DW-MRI (p = 0.001) when evaluating patients at primary diagnosis but no difference was noted in patients treated with chemotherapy. PET/MRI was superior in evaluating high tumour burden in inoperable patients. In the small bowel regions, there was a tendency of higher sensitivity but lower specificity in PET/MRI compared to DW-MRI.ConclusionsOur results suggest that FDG PET/MRI is superior to DW-MRI in estimating total spread of carcinomatosis in gynaecological cancer. Further, the greatest advantage of PET/MRI seems to be in patients at primary diagnosis and with high tumour burden, which suggest that it could be a useful tool when deciding about operability in gynaecological cancer.

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

BackgroundPreoperative 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 methodsIn 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. ResultsThe 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). ConclusionNeither 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.

The Accuracy of the Surgical Peritoneal Cancer Index in Patients with Peritoneal Metastases of Colorectal Cancer

Introduction: The peritoneal cancer index (PCI) is one of the most important prognostic factors in patients with peritoneal metastases from colorectal cancer undergoing cytoreductive surgery and hyperthermic intraperitoneal chemotherapy (CRS-HIPEC). The PCI is determined during laparotomy by 2 experienced surgeons and plays a major role in the decision to proceed with CRS-HIPEC. The primary objective of this study was to determine the accuracy of the surgical PCI (sPCI) by comparing it with the PCI confirmed by the pathologist (pPCI). Methods: All consecutive patients who underwent CRS-HIPEC for colorectal peritoneal metastases between February 2015 and June 2018 were identified. Relevant patient- and tumor-related characteristics were collected. Results: In total, 119 patients were included, 60 males (50.4%). The median age was 64 (IQR 55–71). The median sPCI (sPCI = 11, IQR 6–16) was significantly higher than the median pPCI (pPCI = 8, IQR 3–13, p < 0.001). The total pPCI was lower than the total sPCI in 80 patients (67.2%). In 21 patients (17.6%), the sPCI was overestimated with ≥5 points. Small lesions are more likely to be negative. In patients that underwent resection of their primary tumor prior to CRS-HIPEC, the difference between the sPCI and pPCI was significantly larger (p < 0.05). Conclusions: Surgical calculation of the PCI often results in overestimation. Far-reaching consequences are tied to the macroscopic evaluation of the sPCI, but this evaluation seems not very reliable.

Clinical and Radiologic Predictors of a Pathologic Complete Response to Neoadjuvant Chemotherapy (NACT) in Patients Undergoing Cytoreductive Surgery for Colorectal Peritoneal Metastases: Results of a Prospective Multi-center Study.

Patients undergoing cytoreductive surgery for colorectal peritoneal metastases who have a pathologic complete response (pCR) to neoadjuvant chemotherapy experience a significantly longer survival than those with residual disease. This response is known only after surgery. This study aimed to examine clinical and radiologic predictors of a pCR. From July 2018 to December 2019, the study prospectively enrolled 120 patients. The clinical and radiologic findings were compared between patients with and without a pCR. A protocol for pathologic evaluation was followed. A pCR was observed in 34 patients (28.3%). Receiver operating characteristic (ROC) curves showed that patients with a surgical Peritoneal Cancer Index (sPCI) of 3 or lower had an 80% probability of experiencing a pCR, and that patients with a radiologic PCI (rPCI) of 2 or lower had a 70% probability of experiencing a pCR. A pCR was correctly predicted for 47% of the patients by imaging and for 44.4% of the patients by surgical evaluation. The site of primary tumor, the timing of peritoneal metastasis (PM), histology, tumor marker positivity, and mutations in known poor prognostic genes (KRAS) did not differ between the patients with and those without pCR. The primary tumor showed residual disease in 23.5% and regional nodes in 26.4% of the patients with pCR. The rPCI and sPCI concurred with a pCR in less than 50% of the patients. The patients with a lower PCI had greater concordance. An sPCI of 3 or lower was predictive of a pCR in 80% of the patients. The impact of KRAS mutations on pCR should be evaluated in a larger series. The predictors of pCR and response to systemic chemotherapy should be incorporated in prognostic scores used to select patients for surgery.

Prospective correlation of the radiological, surgical and pathological findings in patients undergoing cytoreductive surgery for colorectal peritoneal metastases: implications for the preoperative estimation of the peritoneal cancer index.

The peritoneal cancer index (PCI) is one of the strongest prognostic factors in patients undergoing cytoreductive surgery (CRS) for colorectal peritoneal metastases. Using pathological evaluation, however, the disease extent differs in a large proportion of patients. Our aim was to study the correlation between the radiological (rPCI), surgical (sPCI) and pathological (pPCI) PCI in order to determine factors affecting the discordance between these indices and their potential therapeutic implications. From July 2018 to December 2019, 128 patients were included in this study. The radiological, pathological and surgical findings were compared. A protocol for pathological evaluation was followed at all centres. All patients underwent a CT scan and 102 (79.6%) had a peritoneal MRI. The rPCI was the same as the sPCI in 81 (63.2%) patients and the pPCI in 93 (72.6%). Concordance was significantly lower for moderate-volume (sPCI 13-20) and high-volume (sPCI>20) disease than for low-volume disease (sPCI 0-12) (P<0.001 for sPCI; P=0.001 for pPCI). The accuracy of imaging in predicting presence/absence of disease upon pathological evaluation ranged from 63% to 97% in the different regions of the PCI. The pPCI concurred with the sPCI in 86 (68.8%) patients. Of the nine patients with sPCI>20, the pPCI was less than 20 in six. The rPCI and sPCI both concurred with pPCI in approximately two thirds of patients. Preoperative evaluation should focus on the range in which the sPCI lies and not its absolute value. Radiological evaluation did not overestimate sPCI in any patient with high/moderate-volume disease. The benefit of CRS in patients with a high r/sPCI (>20) who respond to systemic therapies should be prospectively evaluated.

The Pathologic Peritoneal Cancer Index (PCI) Strongly Differs From the Surgical PCI in Peritoneal Metastases Arising From Various Primary Tumors.

The surgical peritoneal cancer index (sPCI) is calculated based on a subjective evaluation of the extent of peritoneal disease duringsurgery. The pathologic PCI (pPCI) may be a more accurate and objective method for determining the PCI. This study aimed to compare the sPCI and pPCI and to study the potential pitfalls and clinical implications of using the pPCI. This prospective study (July to December 2018) included all patients undergoing cytoreductive surgery (CRS). The pPCI was calculated for each patient and compared with the sPCI. The impact of potential confounding factors on the difference between pPCI and sPCI was evaluated. Among 191 patients undergoing CRS at four centers, the pPCI and sPCI were concordant for 37 patients (19.3%). The pPCI was lower than the sPCI for 125 patients (65.4%) and higher for 29 patients (15.1%). The concordance between the two groups was maximum for gastric cancer (38.8%) and colorectal cancer (27.6%) and least for mesothelioma (6.7%) and rare primary tumors (5.6%) (p = 0.04). The difference was 0 to 3 points for 119 patients (62.3%), 4 to 5 points for 27 patients (14.1%), and more than 5 points for 45 patients (23.5%). The rate of concordance was not influenced by the use of neoadjuvant chemotherapy (NACT) (p = 0.4), but the difference was greater when NACT was used (p = 0.03). The pPCI strongly differs from the sPCI for patients undergoing CRS for peritoneal disease and may provide a more accurate evaluation of the peritoneal disease extent. Further studies are needed to determine its prognostic value compared with sPCI, and consensus guidelines are needed for calculating it.

Value of preoperative ultrasound in evaluating the peritoneal cancer index of pseudomyxoma peritonei

PurposeThis study aimed to explore the value of preoperative ultrasonography (US) in evaluating the peritoneal cancer index (PCI) of pseudomyxoma peritonei (PMP).MethodsAn ultrasound examination was performed on 59 patients with PMP before surgery, and the ultrasound PCI was evaluated. The accuracy of ultrasound PCI score was evaluated with the surgical PCI score as the gold standard.ResultsThe preoperative ultrasound PCI was compared with the surgical PCI. The Spearman correlation coefficient of the total PCI score was 0.608 (P < 0.05). The difference in the Spearman correlation coefficient between the preoperative ultrasound PCI and the surgical PCI in areas 0–7 was statistically significant. (1) Among them, the total score and the correlation between 0–3 and 6 were higher. (2) Compared with the surgical PCI, overestimation (> 20%) was concentrated mainly in areas 2 and 4–8 for 2 points, and underestimation (< 20%) was concentrated mainly in areas 1, 3, 4, and 8 for 3 points. (3) The sensitivity and specificity of preoperative ultrasound for predicting the presence or absence of lesions were 85.7% and 50.0%, respectively. The sensitivity of LS 1, LS 2, and LS 3 was 31.7%, 48.2%, and 71.0%, respectively, and the specificity was 44.8%, 55.3%, and 58.8%, respectively.ConclusionThe ultrasound examination can be used to score the preoperative PCI, judge the severity, and predict the prognosis in patients with PMP.

Accuracy of CT Scan in Predicting the Surgical PCI in Patients Undergoing Cytoreductive Surgery with/without HIPEC-a Prospective Single Institution Study.

Our aim was tostudy the accuracy of CT scan in predicting the peritoneal cancer index (PCI) and the impact of neoadjuvant chemotherapy (NACT), abdominal region, disease volume, and primary tumor site on it. This was a prospective single-center study that included patients undergoing cytoreductive surgery ± HIPEC. The CT-PCI was calculated and compared to the surgical PCI. The accuracy of CT-PCI in predicting the surgical PCI and the difference between the two was evaluated. From January 2018 to August 2018, 50 patients were included. The median CT PCI was 6 (range 0-35) and median surgical PCI was 17 (range 2-35). CT-PCI was more than the surgical PCI in 12 (24%), less in 23 (46%), and same in 15 (30%) with an accuracy of 30%. The highest accuracy was in region 10 and lowest in region 3. It was 15% in patients with ovarian cancer, 30% in PMP, 21% in patients receiving NACT, 35% in high-volume disease, and 42.1% in low volume disease. The CT and surgical PCI varied significantly in patients with ovarian cancer (p < 0.001), following NACT (p = 0.01) and those with moderate volume disease (p < 0.001). CT has a low accuracy in predicting the surgical PCI in both high and low volume disease. The CT-PCI can differ significantly from the surgical PCI in patients with ovarian cancer and in patients who have received NACT for peritoneal disease. The impact of NACT on accuracy of CT-PCI in non-ovarian peritoneal metastases should be evaluated further.

Extended abdominopelvic MRI versus CT at the time of adnexal mass characterization for assessing radiologic peritoneal cancer index (PCI) prior to cytoreductive surgery.

To evaluate whether extending the MRI scan to include the abdomen at the time of adnexal mass characterization could replace additional CT for peritoneal cancer index (PCI) assessment. After institutional review board approval for this prospective study, 36 consecutive females with ovarian and FT malignancies were included. All patients signed an informed consent. Patients underwent preoperative CT (32 patients) and MRI (36 patients). Images were interpreted by 2 independent observers. Surgical data were available in 27 patients. Region-by-region analysis was performed for detection rates of peritoneal carcinomatosis (PC). Inter-observer agreement for each region was evaluated by kappa statistics. Radiologic PCI was calculated by CT and MRI independently and inter-observer agreement for CT and MRI as well as agreement between radiologic and surgical PCI were evaluated by weighted-kappa statistics. On region-by-region analysis, the highest detection rates of PC were noted at the central abdomen and pelvis. Detection rates were higher by MRI than CT, mainly in bowel serosal surface, pelvis, and right upper abdomen regions. Inter-observer agreement of MRI was higher than CT in most regions. The median PCI by CT was 5 and 4 for the first and second observers (range 0-21 for both observers), respectively. The median PCI by MRI was 6 (range 0-23 for both observers). The inter-observer agreement of PCI was excellent by both CT and MRI (k = 0.876 and k = 0.912, respectively). The agreement between CT and surgical PCI was 0.660 and 0.590 for the first and second observers, respectively. The agreement between MRI and surgical PCI was 0.797 and 0.798 for the first and second observers, respectively. Extending MRI scan to include the abdomen at the time of adnexal mass characterization allows accurate estimation of PC, with better results than CT, obviating the need for dedicated CT scan of abdomen and pelvis for imaging of PC.

Diffusion-weighted MRI assessment of the peritoneal cancer index before cytoreductive surgery.

Patients with limited peritoneal metastases from colorectal cancer may be candidates for an aggressive surgical approach including cytoreductive surgery and hyperthermic intraperitoneal chemotherapy (CRS-HIPEC). Selection is based on surgical inspection during laparoscopy or laparotomy. The aim of this study was to investigate whether diffusion-weighted MRI (DW-MRI) can be used to select patients for CRS-HIPEC. This was a prospective study at a tertiary referral centre. Patients with confirmed or suspected colorectal peritoneal metastases scheduled for exploratory laparotomy or laparoscopy were eligible. Two radiologists assessed the peritoneal cancer index (PCI) on CT (CT-PCI) and DW-MRI (MRI-PCI). The reference standard was PCI at surgery. Radiologists were blinded to the surgical PCI and to each other's findings. The main outcome was the accuracy of DW-MRI in predicting whether patients had resectable disease (PCI less than 21) or not. Fifty-six patients were included in the study, of whom 49 could be evaluated. The mean(s.d.) PCI at surgery was 11·27(7·53). The mean MRI-PCI was 10·18(7·07) for reader 1 and 8·59(7·08) for reader 2. Readers 1 and 2 correctly staged 47 of 49 and 44 of 49 patients respectively (accuracy 96 and 90 per cent). Both readers detected all patients with resectable disease with a PCI below 21 at surgery (sensitivity 100 per cent). No patient was overstaged. The intraclass correlation (ICC) between readers was excellent (ICC 0·91, 95 per cent c.i. 0·77 to 0·96). MRI-PCI had a stronger correlation with surgical PCI (ICC 0·83-0·88) than did CT-PCI (ICC 0·39-0·44). DW-MRI is a promising non-invasive tool to guide treatment selection in patients with peritoneal metastases from colorectal cancer.

Diagnostic value of whole-body MRI with diffusion-weighted sequence for detection of peritoneal metastases in colorectal malignancy.

Objective:To assess the diagnostic accuracy of whole-body MRI using diffusion-weighted sequence (WB-DWI) to determine the peritoneal cancer index (PCI) in correlation with surgical and histopathological findings.Methods:Twenty-seven patients underwent preoperative WB-MRI, followed by cytoreductive surgery for primary tumors of the appendix (n = 15), colorectum (n = 12), and associated peritoneal disease. A total of 351 regions were retrospectively reviewed. The sensitivity, specificity, and accuracy were calculated at 13 anatomical sites. The WB-DWI PCI and PCI type were compared with surgical and histopathological findings. Results:No statistical difference was found between the WB-DWI PCI and surgical PCI (P = 0.574). WB-DWI correctly predicted the PCI type in 24 of 27 patients with high accuracy (88.9%), including 10 of 10 patients with small-volume tumor, 12 of 14 with moderate-volume tumor, and 2 of 3 with large-volume tumor. WB-DWI correctly depicted tumors in 163 of 203 regions, with 40 false-negative and 23 false-positive regions. The overall sensitivity, specificity, and accuracy of WB-DWI for the detection of peritoneal tumors were 80.3%, 84.5%, and 82.1%, respectively. For lesions < 0.5 cm in diameter, WB-DWI demonstrated good sensitivity (69.4%). Conclusions:WB-DWI accurately predicted PCI before surgery in patients undergoing evaluation for cytoreductive surgery.