Circadian control of tumor immunosuppression affects efficacy of immune checkpoint blockade.

The circadian clock is a critical regulator of immunity, and this circadian control of immune modulation has an essential function in host defense and tumor immunosurveillance. Here we use a single-cell RNA sequencing approach and a genetic model of colorectal cancer to identify clock-dependent changes to the immune landscape that control the abundance of immunosuppressive cells and consequent suppression of cytotoxic CD8+ T cells. Of these immunosuppressive cell types, PD-L1-expressing myeloid-derived suppressor cells (MDSCs) peak in abundance in a rhythmic manner. Disruption of the epithelial cell clock regulates the secretion of cytokines that promote heightened inflammation, recruitment of neutrophils and the subsequent development of MDSCs. We also show that time-of-day anti-PD-L1 delivery is most effective when synchronized with the abundance of immunosuppressive MDSCs. Collectively, these data indicate that circadian gating of tumor immunosuppression informs the timing and efficacy of immune checkpoint inhibitors.

Fragmentation of Care in Patients with Peritoneal Metastases Undergoing Cytoreductive Surgery.

BACKGROUND: The delivery of multimodal treatment at a high-volume center is known to optimize the outcomes of gastrointestinal malignancies. However, patients undergoing cytoreductive surgery (CRS) for peritoneal metastases often must 'fragment' their surgical and systemic therapeutic care between different institutions. We hypothesized that this adversely affects outcomes. PATIENTS AND METHODS: Adults undergoing CRS for colorectal or appendiceal adenocarcinoma at our institution between 2016 and 2022 were identified retrospectively and grouped by care network: 'coordinated care' patients received exclusively in-network systemic therapy, while 'fragmented care' patients received some systemic therapy from outside-network providers. Factors associated with fragmented care were also ascertained. Overall survival (OS) from CRS and systemic therapy-related serious adverse events (SAEs) were compared across the groups. RESULTS: Among 85 (80%) patients, 47 (55%) had colorectal primaries and 51 (60%) received fragmented care. Greater travel distance [OR 1.01 (CI 1.00-1.02), p = 0.02] and educational status [OR 1.04 (CI 1.01-1.07), p = 0.01] were associated with receiving fragmented care. OS was comparable between patients who received fragmented and coordinated care in the colorectal [32.5 months versus 40.8 months, HR 0.95 (CI 0.43-2.10), p = 0.89] and appendiceal [31.0 months versus 27.4 months, HR 1.17 (CI 0.37-3.74), p = 0.55] subgroups. The frequency of SAEs (7.8% versus 17.6%, p = 0.19) was also similar. CONCLUSIONS: There were no significant differences in survival or SAEs based on the networks of systemic therapy delivery. This suggests that patients undergoing CRS at a high-volume center may safely receive systemic therapy at outside-network facilities with comparable outcomes.

Venous Thromboembolism in Peritoneal Mesothelioma: Uncovering the Hidden Risk.

INTRODUCTION: Venous thromboembolism (VTE) is a common complication in patients with abdominal malignancies. Despite known associations between pleural mesothelioma and increased VTE risk, the characteristics of VTE in patients with peritoneal mesothelioma (PeM) remain undescribed. METHODS: Patients treated for PeM were retrospectively identified from our institutional database. The frequency of VTE was assessed and logistic regression modeling was employed to assess VTE risk factors. The association between VTE and overall survival was also ascertained. Recommended thromboprophylaxis for patients who underwent surgery at our institution comprised a single preoperative dose of prophylactic anticoagulation, followed by daily dosing for four weeks postoperatively. RESULTS: Among 120 PeM patients, 26 (21.7%) experienced VTE, including 19/91 (20.9%) surgical patients, 4/23 (17.4%) patients who received systemic therapy, and 3/6 (50%) patients who underwent observation (p = 0.21). Most events were symptomatic (n = 16, 62%) and were attributable to pulmonary emboli (n = 16, 62%). The 90-day postoperative VTE rate was 4.4% (4/91), including 1 of 60 patients who underwent index surgical intervention at our institution and 3 patients with surgery elsewhere. A low serum albumin concentration was associated with VTE in non-surgical patients (odds ratio 0.12, confidence interval [CI] 0.02-0.72; p = 0.03). No significant difference in overall survival was observed between patients with and without VTE (median 46.0 months [CI 24.9-67.0] vs. 55.0 months [CI 27.5-82.5]; hazard ratio 0.98 [CI 0.54-1.81], p = 0.98). CONCLUSIONS: A high risk of VTE was observed in PeM patients, warranting suspicion throughout the disease trajectory. Postoperative VTE rates were within acceptable limits with 4-week thromboprophylaxis.

Clinical Outcomes in Patients With Krukenberg Tumors From Colorectal Cancer.

INTRODUCTION: Ovarian metastases from gastrointestinal cancers such as colorectal cancer, also known as Krukenberg tumors (KTs), present unique challenges in management due to diagnostic uncertainty, decreased responsiveness to systemic therapies compared to other sites of metastasis, and associated debilitating symptomatology. Thus, we sought to characterize our institutional outcomes in metastatic colorectal cancer (mCRC) patients with KTs. METHODS: A retrospective single-institution study was performed identifying adult, female patients from 2012 to 2021 with a diagnosis of mCRC. Patient demographics and clinicopathologic characteristics were collected and analyzed. Descriptive statistics, univariate and multivariable analyses, and Kaplan-Meier survival analyses were performed. RESULTS: Of 235 mCRC patients, 45 (19.1%) had KTs, 41 (91.1%) of whom had KTs in conjunction with other metastatic sites. Other initial sites of metastasis included the liver (n = 93, 39.6%), lung (n = 28, 11.9%), and peritoneum (n = 18, 7.7%). In the KT cohort, the median age was 48 y, 53.3% were non-Hispanic White, 100% had microsatellite stable tumors, 33.3% had Kristen Rat Sarcoma Virus (KRAS) mutations, and 6.7% had V-raf Murine Sarcoma Viral Oncogene Homolog B (BRAF) mutations. Fifty five point six percent of KT patients underwent cytoreductive surgery (CRS), 24.4% underwent palliative debulking, and 20% underwent no surgical intervention. Reasons for not undergoing CRS were disease-related (n = 14, 70%), due to poor performance status (n = 1, 5%), or both (n = 5, 25%). Five-year overall survival was 48.2% in KT patients who underwent CRS. Poor tumor grade was an independent predictor of mortality (hazard ratio 10.69, 95% confidence interval 1.20-95.47, P = 0.03). CONCLUSIONS: Almost 90% of our patient cohort with KTs from mCRC experience additional sites of metastasis. Around half of KT patients who underwent CRS were alive at 5 y.

Outcomes of parenteral nutrition in patients with advanced cancer and malignant bowel obstruction.

BACKGROUND: Malignant bowel obstruction (MBO) affects 3% to 15% of all cancer patients. In patients with advanced cancer and inoperable MBO, the average survival varies between four to nine weeks. Parenteral nutrition (PN) may improve survival in specific patient populations with malignant bowel obstruction. AIMS: This retrospective, single-center cohort study aimed to review individual patient outcomes on PN in the setting of advanced cancer with a diagnosis of MBO and identify clinical and laboratory markers predictive of short- and long-term survival to further highlight patients that would benefit from PN in the setting of an inoperable MBO. RESULTS: In a retrospective analysis of 68 patients receiving PN for inoperable MBO, the median survival was 142 (IQR: 63.3-239.5) days. Patients experienced a median number of two hospital readmissions (range: 0-10) and spent a median of 29 days (range: 0-105) in the hospital after starting PN. Eighteen (26.5%) patients developed a catheter-related bloodstream infection (CRBSI). A diagnosis of appendiceal cancer was identified as a predictive marker of improved survival (HR: 0.53, 95% CI: 0.29-0.92, p = 0.023). CONCLUSIONS: The use of PN in the context of end-of-life cancer care is a practice that necessitates improvement. Recognizing the outcomes and patient experiences of PN utilization is essential to physicians and patients.

Surgical phenotype of patients with peritoneal mesothelioma and a germline mutation.

BACKGROUND: This study aimed to investigate if peritoneal mesothelioma (PM) patients with germline mutations (GM) have distinct surgical characteristics when compared to those without GM. METHODS: PM patients were selected from an ongoing prospective study that conducts germline testing of 82 susceptibility genes. Germline status was correlated with surgical data obtained from a prospectively collected database using univariate, multivariate, and receiver operating characteristic (ROC) analyses. RESULTS: Out of 88 PM patients enrolled between 2009 and 2019, 18 GMs (20.5%) were identified in BRCA1-associated protein 1 (BAP1) (n = 11, 12.5% of all patients), SDHA (n = 2) and WT1, CDKN2A, CHEK2, ATM, and BRCA2 (n = 1 patient each). Surgical procedures were performed in 71 patients, the most common of which were cytoreductive surgeries with hyperthermic intraperitoneal chemotherapy (n = 61). Patients with GM presented with a higher prevalence of other prior cancers (61.1% vs. 31.4%, p = .02) and lower platelet count (251 [160-413] vs. 367 [196-780] K/µL, p = .005) compared to those without GM (n = 70). Survival outcomes did not differ significantly between the groups. Patients with BAP1 GMs were more likely to develop bicavitary disease and to present with lower platelet count and mitotic count score, and higher peritoneal cancer index (PCI, all p ≤ .04) compared with those without GM. On ROC analysis, the combination of PCI, platelet count and mitotic score yielded an area under the curve of 0.96 (95% CI, 0.91-1.0) for BAP1 GM detection among operated PM patients. CONCLUSION: Higher intraoperative tumor burden and lower platelet count and mitotic score are suggestive of BAP1 GMs in surgical PM patients and should prompt germline testing.

Role of Tumor-informed Personalized Circulating Tumor DNA Assay in Informing Recurrence in Patients With Peritoneal Metastases From Colorectal and High-grade Appendix Cancer Undergoing Curative-intent Surgery.

OBJECTIVE: To investigate the role of a personalized, tumor-informed circulating tumor DNA (ctDNA) assay in informing recurrence in patients with peritoneal metastases (PM) from colorectal (CRC) and high-grade appendix (HGA) cancer after curative cytoreductive surgery with hyperthermic intraperitoneal chemotherapy (CRS-HIPEC). BACKGROUND: Over 50% of patients with CRC/HGA-PM recur after optimal CRS-HIPEC. The limited sensitivity of axial imaging and diagnostic biomarkers is a significant cause of delay in the detection of recurrence and initiation of further therapies. Plasma ctDNA has a promising role in monitoring response to treatment and/or recurrence after primary cancer resection. METHODS: Patients with CRC/HGA-PM who underwent curative CRS-HIPEC and serial postresection ctDNA assessments were included. Patients with rising postoperative ctDNA levels were compared with those with stable, undetectable ctDNA levels. Primary outcomes were the percentage of patients with recurrence and disease-free survival (DFS). Secondary outcomes were overall survival, ctDNA sensitivity, lead time, and performance of ctDNA compared with carcinoembryonic antigen. RESULTS: One hundred thirty serial postresection ctDNA assessments [median 4, interquartile range (IQR), 3 to 5] were performed in 33 patients (n = 13 CRC, n = 20 HGA) who underwent completeness of cytoreduction-0/1 CRS with a median follow-up of 13 months. Of the 19 patients with rising ctDNA levels, 90% recurred versus 21% in the stable ctDNA group (n = 14, < 0.001). Median DFS in the rising ctDNA cohort was 11 months (IQR, 6 to 12) and not reached in the stable ( P = 0.01). A rising ctDNA level was the most significant factor associated with DFS (hazard ratio: 3.67, 95% CI: 1.06-12.66, P = 0.03). The sensitivity and specificity of rising ctDNA levels in predicting recurrence were 85% and 84.6%, respectively. The median ctDNA lead time was 3 months (IQR, 1 to 4). Carcinoembryonic antigen was less sensitive (50%) than ctDNA. CONCLUSIONS: This study supports the clinical validity of serial ctDNA assessment as a strong prognostic biomarker in informing recurrence in patients with CRC/HGA-PM undergoing curative resection. It also holds promises for informing future clinical trial designs and further research.

A Novel Assessment of Metabolic Pathways in Peritoneal Metastases from Low-Grade Appendiceal Mucinous Neoplasms.

BACKGROUND: There is a paucity of targeted therapies for patients with pseudomyxoma peritonei (PMP) secondary to low-grade appendiceal mucinous neoplasms (LAMNs). Dysregulated metabolism has emerged as a hallmark of cancer, and the relationship of metabolomics and cancer is an area of active scientific exploration. We sought to characterize phenotypic differences found in peritoneal metastases (PM) derived from LAMN versus adenocarcinoma. METHODS: Tumors were washed with phosphate-buffered saline (PBS), microdissected, then dissociated in ice-cold methanol dried and reconstituted in pyridine. Samples were derivatized in tert-butyldimethylsilyl (TBDMS) and subjected to gas chromatography-coupled mass spectrometry. Metabolites were assessed based on a standard library. RNA sequencing was performed, with pathway and network analyses on differentially expressed genes. RESULTS: Eight peritoneal tumor samples were obtained and analyzed: LAMNs (4), and moderate to poorly differentiated adenocarcinoma (colon [1], appendix [3]). Decreases in pyroglutamate, fumarate, and cysteine in PM from LAMNs were found compared with adenocarcinoma. Analyses showed the differential gene expression was dominated by the prevalence of metabolic pathways, particularly lipid metabolism. The gene retinol saturase (RETSAT), downregulated by LAMN, was involved in the multiple metabolic pathways that involve lipids. Using network mapping, we found IL1B signaling to be a potential top-level modulation candidate. CONCLUSIONS: Distinct metabolic signatures may exist for PM from LAMN versus adenocarcinoma. A multitude of genes are differentially regulated, many of which are involved in metabolic pathways. Additional research is needed to identify the significance and applicability of targeting metabolic pathways in the potential development of novel therapeutics for these challenging tumors.

PI3K Pathway Alterations in Peritoneal Metastases are Associated with Earlier Recurrence in Patients with Colorectal Cancer Undergoing Optimal Cytoreductive Surgery.

BACKGROUND: Colorectal cancer with peritoneal metastasis (CRC-PM) represents a biologically heterogeneous disease; yet little is known regarding the impact of tumor biology on survival outcomes following optimal cytoreductive surgery (CRS). We analyzed the frequency of alterations in cancer signaling pathways in patients with CRC-PM and their impact on recurrence-free survival (RFS) following optimal CRS. METHODS: Thirty-five consecutive CRC-PM patients who underwent optimal CRS/HIPEC and next generation sequencing of peritoneal metastases were included in the study. Alterations in eight cancer-related signaling pathways were analyzed: Wnt/APC, p53, RTK-RAS, PI3K, TGF-B, Notch, Myc, and cell cycle. The association of pathway alterations with RFS and OS following optimal cytoreduction was estimated using Cox proportional hazard modeling. RESULTS: The most frequently altered pathways were Wnt/APC (63%), p53 (63%), RTK-RAS (60%), and PI3K (23%). Among optimally cytoreduced patients with CRC-PM, PI3K pathway alterations were an independent predictor of worse RFS (hazard ratio 3.2, 95% confidence interval CI 1.3-8.3, p = 0.01) with a clinically meaningful impact on median months to recurrence (5 vs. 13 months, p = 0.02). Alterations in p53, Wnt, and RTK-RAS pathways were not significantly associated with a difference in RFS following CRS. Alterations in the four pathways were not associated with differences in OS following CRS (median OS was 50 (interquartile range 23-80) months). CONCLUSIONS: In patients with CRC-PM, PI3K pathway alterations are associated with earlier recurrence following optimal CRS, which may represent a distinct molecular subtype. This novel finding can tailor clinical trials by using PIK3CA-directed interventions to reduce risk of recurrence after optimal CRS.

Design and Implementation of a Learner-Centered Self-Paced Peritoneal Oncology Education Program.

BACKGROUND: Current educational programs for peritoneal surface malignancies (PSM) are unstructured and often target advanced learners. The authors describe the design and implementation of a structured, self-paced course at a high-volume PSM center. METHODS: In 2020, a learner-centered course was designed using the Canvas educational platform in consultation with the Center for Teaching at the University of Chicago. The course consisted of disease-site-specific modules, perioperative care pathways, in-built voluntary quizzes, and multimedia supplements for advanced learners. Trainees were provided access during the PSM service rotation, and engagement was compared across training levels by measuring the time spent online. RESULTS: Course design and management required 71 h between 2020 and 2022, with the majority of time spent in the design phase. During 3 years, 62 personnel (21 [34%] medical students, 28 [45%] residents, 8 [13%] staff, and 5 [8%] fellows) were assigned the course. The overall engagement rate was 83.9% (86% of medical students, 75% of residents, 100% of staff and fellows), and the median time spent online was 12.4 min/week (interquartile range [IQR], 2.1-53.0 min/week). Fourth-year medical students and clinical fellows spent more time online than other learners (73 min/week [IQR, 24.5-100 min/week] vs 13.3 min/week [IQR, 7.3-26.5 min/week]) (p = 0.001). CONCLUSIONS: The design and implementation of a PSM-specific course was feasible and sustainable using an online learning platform. Higher engagement was noted among invested learners. Non-technical factors for reduced engagement need to be ascertained further to improve the next iteration of this course.

Insurance Authorization Barriers in Patients Undergoing Cytoreductive Surgery and HIPEC.

BACKGROUND: Indications for cytoreductive surgery (CRS) and hyperthermic intraperitoneal chemotherapy (HIPEC) exist across multiple histologies, but little data exist on the impact of insurance authorization on access to these therapies. Given the evolving role of CRS/HIPEC, we sought to characterize insurance approval and delays in patients undergoing these therapies. PATIENTS AND METHODS: A retrospective review was performed at a high-volume tertiary center of patients who received CRS/HIPEC from 2017 to 2021. Collected data included patient demographics, tumor histologic characteristics, insurance type, approval/denial history, and time to prior authorization approval. Descriptive statistics were performed. RESULTS: In total, 367 patients received CRS/HIPEC during the study period. They had a median age of 59 (IQR 49-67) years, 35% were male, and 76% were white. Of the patients requiring prior authorization, 14 of 104 (13%) patients were denied prior authorization and required appeal. Median time between authorization request and approval was 33 (IQR 28-36) days. These cases generated 410 insurance authorization requests, 94 (23%) of which were not initially approved and required appeal. The rate of upfront denial was 21.1% in patients with public insurance compared with 23.4% in patients with private insurance. Gastric cancer was the most common histology among denied cases (55%), followed by colorectal, appendiceal, and gynecologic malignancies. CONCLUSIONS: Despite the broadening indications for and data supporting CRS/HIPEC, a significant proportion of patients still face hurdles in attaining insurance approval and coverage for these therapies. Addressing barriers to insurance approval is imperative to decrease therapeutic delay and improve access to data-driven care.

Palliative Care and Characterization of Symptoms in Patients Undergoing Cytoreductive Surgery/Hyperthermic Intraperitoneal Chemotherapy.

INTRODUCTION: Palliative care for advanced cancer patients has been associated with improvements in symptom management and quality of life (QoL). Patients with peritoneal metastases undergoing cytoreductive surgery (CRS) and hyperthermic intraperitoneal chemotherapy (HIPEC) often report symptoms adversely affecting QoL. We characterized and compared symptoms elucidated by palliative care versus surgical providers in this setting. METHODS: CRS/HIPEC patients who saw both surgical oncology and palliative care providers from 2016 to 2020 at a tertiary care center were identified from a retrospective database. Documentation of QoL-associated symptoms in surgical oncology and palliative care visits was recorded and analyzed. RESULTS: A total of 118 patients were included in this study. The most common primary histologies were appendiceal (36.4%) and colorectal (28.8%). Symptoms most frequently reported by palliative care were pain (60.2%) and fatigue (54.2%). The median number of symptoms documented was three (2, 5) in palliative care notes and two (0, 3) in surgical oncology notes (P < 0.001). Palliative care providers documented most symptoms statistically more frequently than surgical oncology providers. CONCLUSIONS: Patients who underwent CRS/HIPEC experienced various QoL-associated symptoms. Palliative care providers elicited more symptoms than surgical oncology providers. Additional studies are needed to explore the impact on outcomes of perioperative palliative care in this challenging patient population.

Mutational profiles and prognostic impact in colorectal and high-grade appendiceal adenocarcinoma with peritoneal metastases.

BACKGROUND: Next-generation sequencing (NGS) personalizes cancer treatments. In this study, we analyze outcomes based on NGS testing for colorectal cancer (CRC) and high-grade appendiceal adenocarcinoma (HGA) with peritoneal metastases. METHODS: Retrospective review of genomic analyses and outcomes in patients with CRC or HGA with peritoneal metastases at a high-volume center from 2012 to 2019. RESULTS: Ninety-two patients (57 CRC, 35 HGA) were identified. Overall survival was longer for CRC (52.8 vs. 30.5 months, p = 0.03), though rates of cytoreductive surgery with hyperthermic intraperitoneal chemotherapy (CRS/HIPEC) were similar. Multiple genes were more frequently mutated in CRC, including KRAS (51% vs. 29%, p = 0.04), TP53 (47% vs. 20%, p < 0.01), and APC (46% vs. 6%, p < 0.01). For CRC, multivariate regression showed an increased hazard ratio (HR) with increasing peritoneal cancer index (1.06 [1.01-1.11], p = 0.02) and a decreased HR following CRS/HIPEC (0.30 [0.11-0.80], p = 0.02). PIK3CA mutation associated with significantly increased HR (3.62 [1.06-12.41], p = 0.04), though only in non-CRS/HIPEC patients. Multivariate analysis in the HGA group showed a benefit following CRS/HIPEC (0.18 [0.06-0.61], p = 0.01) and for mucinous disease (0.38 [0.15-0.96], p = 0.04), while there was an increased HR with TP53 mutation (6.89 [2.12-22.44], p < 0.01). CONCLUSION: CRC and HGA with peritoneal spread have distinct mutational profiles. PIK3CA and TP53 mutations are associated with survival for CRC or HGA with peritoneal metastases, respectively.

Phase II Prospective, Open-Label Randomized Controlled Trial Comparing Standard of Care Chemotherapy With and Without Sequential Cytoreductive Interventions for Patients with Oligometastatic Foregut Adenocarcinoma and Undetectable Circulating Tumor Deoxyribose Nucleic Acid (ctDNA) Levels.

BACKGROUND: Metastatic adenocarcinomas of foregut origin are aggressive and have limited treatment options, poor quality of life, and a dismal prognosis. A subset of such patients with limited metastatic disease might have favorable outcomes with locoregional metastasis-directed therapies. This study investigates the role of sequential cytoreductive interventions in addition to the standard of care chemotherapy in patients with oligometastatic foregut adenocarcinoma. METHODS: This is a single-center, phase II, open-label randomized clinical trial. Eligible patients include adults with synchronous or metachronous oligometastatic (metastasis limited to two sites and amenable for curative/ablative treatment) adenocarcinoma of the foregut without progression after induction chemotherapy and having undetectable ctDNA. These patients will undergo induction chemotherapy and will then be randomized (1:1) to either sequential curative intervention followed by maintenance chemotherapy versus routine continued chemotherapy. The primary endpoint is progression-free survival (PFS), and a total of 48 patients will be enrolled to detect an improvement in the median PFS in the intervention arm with a hazard ratio (HR) of 0.5 with 80% power and a one-sided alpha of 0.1. Secondary endpoints include disease-free survival (DFS) in the intervention arm, overall survival (OS), ctDNA conversion rate pre/post-induction chemotherapy, ctDNA PFS, PFS2, adverse events, quality of life, and financial toxicity. DISCUSSION: This is the first randomized study that aims to prospectively evaluate the efficacy and safety of surgical/ablative interventions in patients with ctDNA-negative oligometastatic adenocarcinoma of foregut origin post-induction chemotherapy. The results from this study will likely develop pertinent, timely, and relevant knowledge in oncology.

Management of colorectal cancer during the COVID-19 pandemic: Recommendations from a statewide multidisciplinary cancer collaborative.

COVID-19 has resulted in significant disruptions in cancer care. The Illinois Cancer Collaborative (ILCC), a statewide multidisciplinary cancer collaborative, has developed expert recommendations for triage and management of colorectal cancer when disruptions occur in usual care. Such recommendations would be applicable to future outbreaks of COVID-19 or other large-scale disruptions in cancer care.

The role of cytoreductive surgery and intraperitoneal chemotherapy in gastric cancer.

Gastric cancer (GC) with peritoneal carcinomatosis (PC) progresses rapidly and has historically dismal survival rates. Given the aggressive tumor biology and poor survival outcomes of patients with GC/PC, additional treatments beyond systemic chemotherapy are needed. Cytoreductive surgery and intraperitoneal chemotherapy have been effective management options for peritoneal surface malignancies, with increasing data to support their use in GC/PC. This review highlights the evolution of the surgical treatment of GC/PC, and discusses critical studies supporting the role of cytoreductive surgery, appropriate patient selection, and various methods in the delivery of intraperitoneal chemotherapy for patients with GC/PC.

Heterogeneity in PD-L1 expression in malignant peritoneal mesothelioma with systemic or intraperitoneal chemotherapy.

Programmed death-ligand 1 (PD-L1) expression has been described in patients with malignant peritoneal mesothelioma (MPM), but treatment strategies utilising immune checkpoint inhibition are yet to be defined. Here, we examine levels of PD-L1 expression in MPM patients treated with systemic and/or intraperitoneal chemotherapy using tissue from patient tumour biopsies or resections at multiple time points. We found the mean PD-L1 expression was higher in those with a germline mutation and/or those with a higher somatic mutation burden. Moreover, PD-L1 expression was lower in patients who had received prior chemotherapy as compared to the treatment-naive cohort. Twenty patients who received chemotherapy, either systemic and/or peritoneal, between PD-L1 measurements showed marked heterogeneity. Six (30%) patients demonstrated upregulation of PD-L1, while eight (40%) demonstrated downregulation. Heterogeneity in PD-L1 expression in MPM before and after cytotoxic therapies may present an additional consideration when initiating immune checkpoint inhibition in this rare and challenging disease.

Cytoreductive Surgery for Selected Patients Whose Metastatic Gastric Cancer was Treated with Systemic Chemotherapy.

BACKGROUND: The authors hypothesized that cytoreductive surgery (CRS, comprising gastrectomy combined with metastasectomy) in addition to systemic chemotherapy (SC) is associated with a better survival than chemotherapy alone for patients with metastatic gastric adenocarcinoma (MGA). METHODS: Patients with MGA who received SC between 2004 and 2016 were identified using the National Cancer Database (NCDB). Nearest-neighbor 1:1 propensity score-matching was used to create comparable groups. Overall survival (OS) was compared between subgroups using Kaplan-Meier analyses. Immortal bias analysis was performed among those who survived longer than 90 days. RESULTS: The study identified 29,728 chemotherapy-treated patients, who were divided into the following four subgroups: no surgery (NS, n = 25,690), metastasectomy alone (n = 1170), gastrectomy alone (n = 2248), and CRS (n = 620) with median OS periods of 8.6, 10.9, 14.8, and 16.3 months, respectively (p < 0.001). Compared with the patients who underwent NS, the patients who had CRS were younger (58.9 ± 13.4 vs 62.0 ± 13.1 years), had a lower proportion of disease involving multiple sites (4.6% vs 19.1%), and were more likely to be clinically occult (cM0 stage: 59.2% vs 8.3%) (p < 0.001 for all). The median OS for the propensity-matched patients who underwent CRS (n = 615) was longer than for those with NS (16.4 vs 9.3 months; p < 0.001), including in those with clinical M1 stage (n = 210). In the Cox regression model using the matched data, the hazard ratio for CRS versus NS was 0.56 (95% confidence interval [CI], 0.49-0.63). In the immortal-matched cohort, the corresponding median OS was 17.0 versus 9.5 months (p < 0.001). CONCLUSIONS: In addition to SC, CRS may be associated with an OS benefit for a selected group of MGA patients meriting further prospective investigation.

Novel Application of Iterative Hyperthermic Intraperitoneal Chemotherapy for Unresectable Peritoneal Metastases from High-Grade Appendiceal Ex-Goblet Adenocarcinoma.

BACKGROUND: Peritoneal metastases (PMs) from appendiceal ex-goblet adenocarcinoma (AEGA) are associated with a poor prognosis. While cytoreductive surgery (CRS) with hyperthermic intraperitoneal chemotherapy (HIPEC) has been shown to prolong survival, the majority of patients are ineligible for complete cytoreduction. We describe a novel approach to the management of such patients with iterative HIPEC (IHIPEC). METHODS: Patients with signet ring/poorly differentiated AEGA with high Peritoneal Cancer Index (PCI) and extensive bowel involvement underwent IHIPEC with mitomycin C at 6-week intervals for a total of three cycles. Survival outcomes for these patients were compared with patients with high-grade appendiceal tumors matched for tumor burden who were treated with other conventional approaches, i.e. systemic chemotherapy only (SCO) or complete CRS + HIPEC. RESULTS: Between 2016 and 2019, seven AEGA patients with high PCI (median 32.5 [range 21-36]) underwent 18 IHIPEC cycles (median cycles per patient 3 [2-3]) in combination with systemic chemotherapy (median 2 lines [1-3], 12 cycles [10-28]). IHIPEC was delivered laparoscopically in 14/18 cases. Postoperatively, the median length of stay was 1 day (1-8 days), no procedure-related complications were reported, and five (28%) 90-day readmissions for bowel obstruction were documented. Median overall survival after IHIPEC was better compared with a matched group of patients (n = 16) receiving SCO (24.6 vs. 7.9 months; p = 0.005), and similar to those (n = 7) who underwent CRS + HIPEC (24.6 vs. 16.5 months; p = 0.62). CONCLUSIONS: IHIPEC in combination with systemic chemotherapy is tolerable, safe, and may be associated with encouraging survival outcomes compared with SCO in selected patients with high-grade, high-burden AEGA PM.

Differences in Sociodemographic Disparities Between Patients Undergoing Surgery for Advanced Colorectal or Ovarian Cancer.

BACKGROUND: Cytoreductive surgery (CRS) for ovarian cancer with peritoneal metastases (OPM) is an established treatment, yet access-related racial and socioeconomic disparities are well documented. CRS for colorectal cancer with peritoneal metastases (CRPM) is garnering more widespread acceptance, and it is unknown what disparities exist with regards to access. METHODS: This retrospective cross-sectional multicenter study analyzed medical records from the National Cancer Database from 2010 to 2015. Patients diagnosed with CRPM or ORP only and either no or confirmed resection were included. Patient- and facility-level characteristics were analyzed using uni- and multivariable logistic regressions to identify associations with receipt of CRS. RESULTS: A total of 6634 patients diagnosed with CRPM and 14,474 diagnosed with OPM were included in this study. Among patients with CRPM, 18.1% underwent CRS. On multivariable analysis, female gender (odds ratio [95% CI] 2.04 [1.77-2.35]; P < 0.001) and treatment at an academic or research facility (OR 1.55 [1.17-2.05]; P = 0.002) were associated with CRS. Among patients with OPM, 87.1% underwent CRS. On multivariable analysis, treatment at facilities with higher-income patient populations was positively associated with CRS, while age (OR 0.97 [0.96-0.98]; P < .0001), use of nonprivate insurance (OR 0.69 [0.56-0.85]; P = 0.001), and listed as Black (OR 0.62 [0.45-0.86]; P = 0.004) were negatively associated with CRS. CONCLUSION: There were more systemic barriers to CRS for patients with OPM than for patients with CRPM. As CRS becomes more widely practiced for CRPM, it is likely that more socioeconomic and demographic barriers will be elucidated.