BACKGROUND:Peritoneal metastases from colorectal cancer (pmCRC) are associated with poor prognosis. Neoadjuvant chemotherapy followed by cytoreductive surgery (CRS) and hyperthermic intraperitoneal chemotherapy (HIPEC) has improved survival in these patients. However, few studies have evaluated the influence of radiological and pathological responses on overall survival (OS) and recurrence-free survival (RFS) in this population. OBJECTIVE:The objective of this study was to assess these prognostic markers in patients with pmCRC who received neoadjuvant chemotherapy followed by CRS-HIPEC at our institution. METHODS:A total of 121 patients with pmCRC treated with neoadjuvant chemotherapy followed by CRS-HIPEC from 2012 to 2023 were included. Demographic, clinical, and oncological data were extracted from medical records. OS and RFS were obtained using Kaplan-Meier analysis. Univariate and multivariate Cox regression analyses were done. RESULTS:After a median follow-up of 44.6 months, median OS was 47.1 months (95% confidence interval [CI] 32.4-61.6) and RFS was 21.8 months (95% CI 13.7-29.9). No significant difference in OS was observed among patients who achieved a partial response on imaging compared with non-responders (hazard ratio [HR] 0.9; 95% CI 0.5-1.5; p = 0.725). Patients who did not achieve a complete pathological response showed a significant difference in OS, with worse OS (HR 3.4; 95% CI 1.3-8.9; p = 0.012). OS was significantly lower in patients with a peritoneal carcinomatosis index >15 (HR 4.1; 95% CI 1.1-15; p = 0.033). CONCLUSIONS:Radiological response after neoadjuvant chemotherapy does not significantly affect the OS or RFS of patients with pmCRC. Complete pathological response is a significant prognostic marker for both OS and RFS.

Preoperative colonoscopy is recommended for colorectal cancers to exclude synchronous tumors. However, data are lacking regarding this recommendation for appendiceal mucinous neoplasms. This study evaluated whether preoperative colonoscopy in patients with appendiceal mucinous lesions would reveal a significant finding, modify the operative plan, or be associated with adverse events. This mixed-methods retrospective cohort study included all mucinous appendiceal neoplasms between 2017 and 2024 at a tertiary care hospital. Overall, 100 patients were included: 15

INTRODUCTION:Despite advances in systemic therapy, metastatic gastric cancer is associated with a poor prognosis. As peritoneal disease is common, several studies looked at the potential benefits of hyperthermic intraperitoneal chemotherapy (HIPEC) in this context, with encouraging results. However, no Canadian data currently exists on the subject. MATERIALS AND METHODS:This study aims to report characteristics and outcomes of Canadian patients who underwent cytoreductive surgery and HIPEC (CRS-HIPEC) for gastric cancer associated with peritoneal disease or positive peritoneal cytology. This multicenter retrospective study included patients 18 years or older with gastric cancer associated with isolated peritoneal involvement who underwent CRS-HIPEC in five tertiary centers from 2016 to 2022. RESULTS:CRS-HIPEC was performed on 20 patients aged 34-69 years old, most of whom presented with poorly differentiated (90 %) adenocarcinoma, with synchronous peritoneal disease (95 %). Median PCI was 3 (0-13). The associated 90-day morbidity rate, defined as Clavien-Dindo grade III and above complications, was 10 %. At a mean follow-up of 23.3 months (range 4-48), 25 % of patients remained disease-free, with an estimated median overall survival of 24.2 months. CONCLUSION:CRS-HIPEC for gastric cancer can achieve longer term survival in highly selected patients with low-burden peritoneal disease or positive cytology. Ongoing randomized trials will further clarify patients' selection criteria and benefits of this approach.

Goals: Cytoreductive surgery (CRS) and hyperthermic intraperitoneal chemotherapy (HIPEC) improve survival in patients with peritoneal metastases (PM). While mitomycin-C (MMC) and oxaliplatin are the primary HIPEC agents for colorectal and appendiceal PM, previous studies comparing both agents relied on outdated low-dose MMC regimens. This study evaluates the safety of high-dose 35 mg/m(2) mitomycin C vs 460 mg/m(2) oxaliplatin. Methods: This retrospective cohort study analyzed all patients with appendiceal and colorectal PM treated at a tertiary-care hospital from 2014 to 2024. Results: Among 282 patients, 48 (17.0 %) received high-dose MMC and 234 (83.0 %) received oxaliplatin. Patient demographics and oncological characteristics were similar (p > 0.05). High-dose MMC had significantly more toxic events (35.4 % vs 14.1 %, p < 0.001), greater CTCAE median toxicity grade (2 vs 1, p < 0.001), higher hepatic cytolysis (2.1 % vs 0.0 %, p = 0.027), increased neutropenia (27.1 % vs 4.3 %, p < 0.001), more gastric perforations (4.2 % vs 0 %, p = 0.002) as well as one case of HIPEC toxicity-related death due to neutropenic enterocolitis (2.1 % vs 0.0 %, p = 0.380). Oxaliplatin resulted in more hematomas (12.0 % vs 2.1 %, p = 0.040), higher need for parenteral nutrition (94.0 % vs 83.3 %, p = 0.012), and longer duration of nutritional support (12.3d vs 8.6d, p = 0.020). High-dose MMC had higher abdominal sepsis rates (6.3 % vs 1.3 %, p = 0.030). Severe complications, reintervention, ICU transfers, and 90-day mortality were similar (p > 0.05). Length of stay was shorter for high-dose MMC (14.7d vs 17.7d, p = 0.031). Conclusion: High-dose MMC was associated with increased HIPEC toxicity, primarily neutropenia-related. Clinicians must balance the benefits and drawbacks of high-dose MMC and oxaliplatin to provide an optimal and individualized treatment.

BACKGROUND:A novel approach using single-fraction preoperative partial breast irradiation (PBI) for low-risk breast cancer is under study. We sought to investigate the rate of pathologic response (pR), toxicities and cosmetic results related to this new treatment strategy. METHODS:Women of 65 years or older with stage I unifocal luminal A breast cancer were eligible for inclusion in this phase I prospective trial. Patients received a single 20 Gy dose of PBI followed by breast-conserving surgery (BCS) 3 months later. The primary endpoint was the pR rate, and the secondary endpoints were radiation therapy-related toxicity and cosmetic results. RESULTS:Thirteen patients were treated, with a median age of 71. Eleven patients (84.6 %) had pR with a median residual cellularity of 1 % (range: 0-10 %). At median follow-up of 48.5 months, no recurrences or cancer-related deaths were recorded. Acute radiation therapy-related toxicity were limited to grade 1 dermatitis and breast pain. At the 1-year follow-up, there were one grade 2 fat necrosis and two grade 3 toxicities (wound infection and hematoma). Only grade 1 toxicities remained at 2 years, but one grade 2 toxicity (fibrosis/induration) developed by the 3-year follow-up. Three-year patient-reported cosmetic outcomes were good or excellent in 60 % of patients. CONCLUSIONS:Single-fraction preoperative PBI preceding BCS for low-risk breast cancer is feasible, relatively well tolerated and leads to a high level of pR. The 3-month interval after PBI seems to place surgery in a post-radiation inflammatory phase. Further delay between PBI and surgery could improve pR and cosmetic outcome. NCT03917498.

Data regarding the safety of concurrent olaparib and radiation therapy in patients with BRCA1/2-mutated breast cancer are very limited. We report the case of a 45-year-old woman treated with concurrent adjuvant olaparib and radiation therapy for a recurrent BRCA2-mutated breast cancer presenting with a synchronous advanced-stage ovarian cancer. The patient received standard-dose locoregional radiation therapy to the ipsilateral breast, axilla, supraclavicular region, and internal mammary chain, with concurrent reduced-dose olaparib. The treatment was well tolerated with no unexpected acute toxicity. Further clinical trials are needed to confirm the safety and efficacy of concurrent olaparib and radiation therapy in this patient population.

Background: Although the role of the 21-gene Breast Recurrence Score® assay is well established to predict response to adjuvant chemotherapy in the setting of node-negative hormone receptor (HR)-positive, HER2-negative breast cancers (BC), fewer studies have evaluated the assay in the neoadjuvant setting. Due to the correlation between a high Recurrence Score® (RS) result and pathological complete response (pCR), the Breast Recurrence Score assay has been used to aid in selecting between chemotherapy (CT) or endocrine therapy. We wanted to further understand the impact of the assay upon physician treatment recommendations and the use of chemotherapy in this patient cohort. Methods: We conducted a multicenter, prospective, observational study in patients with clinically node-negative HR-positive, HER2-negative BC with T2-T3 disease being considered for neoadjuvant therapy. Physicians were required to complete two questionnaires indicating treatment choice, including CT, endocrine therapy, or surgery, prior to and post availability of RS result. Patients were followed up for 6 months after commencement of neoadjuvant therapy. The primary objective was to evaluate the change in the physician’s recommendation for neoadjuvant CT prior to and post assay results. As a secondary objective, we also evaluated the impact of the RS result on physician’s expressed level of confidence. Results: A total of 70 patients were enrolled between April 2018 and November 2021 at five hospital centers, as part of the McPeak Sirois Group of Quebec. The median age of the cohort was 60 years (range, 30 to 79 years). 24.3 % (n=17) of the cohort consisted of patients aged < 50 years, and 75.7% (n=53) were ≥ to 50 years. 29.0% (n=20) of the patients had a RS < 16, 39.1% (n=27) had a RS between 16-25, and 31.9% (n=22) had a RS > 25. For the entire cohort, the RS result led to a net reduction in chemotherapy recommendation by 33.3% (OR (odds of having CT post-RS recommendation versus pre-RS recommendation) = 0.23 [95% CI: 0.12-0.44]; P< 0.0001), and 39.2% net reduction in the use of chemotherapy at 6-month follow-up (OR = 0.18 [95% CI: 0.09-0.35]; P< 0.0001). Furthermore, the RS result led to a 35.3% net reduction in physician recommendation of CT for patients < 50 years (OR = 0.19 [95% CI: 0.04-0.83]; P=0.027) and a 32.7% net reduction for patients ≥ 50 years (OR = 0.24 [95% CI: 0.11-0.50]; P=0.0001). For patients with a RS < 16, there was a reduction in CT recommendation by 75.0%, and by 44.4% for patients with a RS between 16 - 25 (OR = 0.15 [95% CI: 0.06-0.38]; P< 0.0001). Moreover, RS results led to an increase in confidence in physician treatment decisions for 59.4% of patients (OR = 12.53 [95% CI: 5.46-28.78]; P< 0.0001). Conclusion: We determined that the 21-gene Breast Recurrence Score assay altered neoadjuvant treatment decisions, leading to a reduction in the use of chemotherapy by about one-third, regardless of age. Additionally, the assay increased physician confidence in their treatment recommendation for about 60% of patients. This demonstrates the potential clinical utility of the assay to decrease the use of CT in the neoadjuvant setting amongst HR-positive, node-negative BC patients in Quebec. Citation Format: Mariya Yordanova, Lucas Sideris, Pierre Dubé, Jean-Francois Boileau, Julie Lemieux, Catalin Mihalcioiu, Sylvie Levesque, Marie-Claude Guertin, Erica Patocskai, Rami Younan, André Robidoux, Saima Hassan. The impact of the 21-gene Recurrence Score® assay upon physician treatment recommendations in the neoadjuvant setting in lymph node-negative breast cancer patients in a multicenter prospective study in Quebec [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr P6-01-39.

Peritoneal mesothelioma (PM) is a rare malignancy originating from the peritoneal lining. Cytoreductive surgery (CRS) and heated intraperitoneal chemotherapy (HIPEC) is the standard‐of‐care for patients with isolated PM. Due to a paucity of prospective data there are several different HIPEC protocols. The aims of this study are to describe the CRS and HIPEC protocols for PM and patient outcomes across Canada.

Combining interval cytoreductive surgery (CRS) with hyperthermic intraperitoneal chemotherapy (HIPEC) improves survival in advanced epithelial ovarian carcinoma (EOC). Although limited, growing evidence regarding carboplatin-based HIPEC highlights its potential. This retrospective study included all patients with advanced primary high-grade serous ovarian cancer who underwent interval CRS combined with carboplatin-based HIPEC at our Canadian tertiary care center between 2014 and 2020. We identified 40 patients with a median age of 61 years. The median peritoneal cancer index was 13 and complete cytoreduction was achieved in 38 patients (95%). Median hospital stay was 13 days and there were four admissions to the intensive care unit (10%) and six readmissions (15%). Severe adverse events occurred in eight patients (20%) and there was no perioperative death. Recurrence was seen in 33 patients (82%) with a median DFS of 18.0 months and a median overall survival of 36.4 months. Multivariate analyses showed that age, peritoneal cancer index, completeness of cytoreduction, occurrence of severe complications, and bowel resection did not significantly impact DFS or OS in our cohort. Interval CRS combined with carboplatin-based HIPEC for advanced primary EOC is associated with acceptable morbidity and oncological outcomes. Larger studies are required to determine the long-term outcomes.

Abstract Background The 21-gene Breast Recurrence Score (RS) assay, “the assay”, has led to a paradigm shift for patients with hormone receptor-positive, node-negative early breast cancer and is emerging as an important tool to assist physician-patient decisions in foregoing chemotherapy in node-positive patients. We wanted to better understand the impact of the RS assay in node-positive patients upon physician treatment decisions and treatment cost in Quebec, Canada. Patients and Methods We conducted a multicenter, prospective observational trial for Estrogen/Progesterone Receptor (ER/PR)- positive, Human Epidermal Growth Factor Receptor 2 (HER2)-negative breast cancer patients with 1-3 positive lymph nodes. Physicians completed a questionnaire indicating treatment choice prior to and post availability of RS results. The primary endpoint was change in the physician’s recommendation for chemotherapy prior to and post assay results. Secondary endpoints included change in physician’s expressed level of confidence, and changes in estimated cost of recommended treatments prior to and post assay results. Results For the entire cohort, physician recommendation for chemotherapy was reduced by an absolute 67.1% by knowledge of the RS assay result (P < .0001). Physician recommendation of chemotherapy was decreased by 75.9% for patients RS result <14 (P < .0001); and 67.5% for patients with RS result 14-25 (P < .0001). Changes in treatment recommendations were associated with an overall reduction in cost by 73.7% per patient, and after incorporating the cost of the RS test, a cost benefit of $823 CAN at 6-month follow-up. Conclusion Altogether, we established that the assay led to a two-third reduction in the use of chemotherapy, and was a cost-effective approach for hormone receptor-positive, node-positive breast cancer.

BACKGROUND:Pathologic examination of post-neoadjuvant chemotherapy (NAC) breast surgical specimens includes assessment of margins. It has been recommended that tumor bed (TB) changes extending to margins should be documented; however, its' incidence and clinical significance have not yet been established. The aim of our study was to gather prognostic data on this histological finding. DESIGN:We retrospectively identified all cases where TB was reported at margin. Cases where margins were also positive for invasive carcinoma or DCIS were excluded. RESULTS:From 2016 to 2019, 115 cases of NAC treated breast cancers were identified with 21 having at least one margin positive for TB after initial surgery (incidence of 18.3 %). Five cases were estrogen receptor (ER)-/HER2-, 9 were HER2+ and 7 were ER+/HER2-. Nineteen patients underwent partial mastectomy and 2 underwent total mastectomy. Nine patients had a pathological complete response (pCR).Ten cases had more than one positive margin for TB. None of the 21 patients underwent a second surgery for margin re-excision. Twenty patients received adjuvant therapy. With an average follow-up of 28.1 months, there has been one local recurrence. Four other patients developed metastatic disease, one of which died of the disease. The rates of locoregional and distant recurrence and mortality were statistically similar to those from patients whose margins were negative for TB. CONCLUSIONS:Our results suggest low risk of local recurrence when a positive margin for TB is not re-excised. Further data and follow-up will be needed to confirm the adequacy of conservative management in this setting.

Cytoreductive surgery with hyperthermic intraperitoneal chemotherapy (CRS-HIPEC) is a treatment option for peritoneal metastases (PM) but is associated with significant postoperative morbidity. The aim of this study was to determine the prognostic value of computed tomographic (CT)-measured sarcopenia on postoperative outcomes and survival in patients undergoing CRS-HIPEC for PM from various origins. A retrospective cohort study was conducted between 2012 and 2020. Three-hundred and twelve patients (mean age 57.6 ± 10.3, 34.3% male) were included, of which 88 (28.2%) were sarcopenic. PM from a colorectal origin was the most common in both groups. The proportion of major postoperative complications (Clavien-Dindo ≥ III) was not higher in the sarcopenic group (15.9% in sarcopenic patients vs. 23.2% in nonsarcopenic patients, p = 0.17). The mean Comprehensive Complication Index scores, HIPEC-related toxicities, length of hospital stay, and duration of parenteral nutrition were comparable regardless of sarcopenia status. In the multivariate logistic regression analysis of severe complications, only peritoneal carcinomatosis index reached statistical significance (OR, 1.05; 95% CI, 1.01 to 1.08, p = 0.007). Sarcopenia did not impact origin-specific overall survival on Cox regression analysis. Sarcopenia was not associated with worse rates of postoperative severe complications or worse survival rates. Future prospective studies are required before considering sarcopenia as part of preoperative risk assessment.

Abstract Background With their demanding schedules, surgical residents have limited time to practice techniques. The aim is to evaluate the pedagogic model of self-directed learning using video in surgery residents. Methods Informed consent was obtained from all the participants. A randomized controlled trial was conducted in 2018 at Hôpital Maisonneuve-Rosemont (University of Montreal). Participants were general surgery residents. There were 27 eligible residents; 22 completed the study. They were filmed performing an intestinal anastomosis on cadaveric pig bowel. The self-directed learning by video (SDL-V) group was given an expert video, which demonstrated the technique performed by an experienced surgeon. The control group continued with their regular duties. Three weeks later, participants performed a second filmed anastomosis. Two attending surgeons evaluated the residents’ filmed anastomosis using the Objective Structured Assessment of Technical Skills scale. After their second anastomosis, all participants had access to the expert video and completed a survey. Results Score did not differ significantly between groups during the first (control: 23.6 (4.5) vs. SDL-V: 23.9 (4.5), p = 0.99, presented as mean (SD)) or second filmed anastomosis procedure (control: 27.1 (3.9) vs. SDL-V: 29.6 (3.4) p = 0.28). Both groups improved significantly from pre- to post-intervention (mean difference between the two anastomosis procedure with 95% CI for control: 3.5, [1.1; 5.9] and for SDL-V: 5.8, [3.4: 8.2]). Correlation between the evaluators for score was moderate (r = 0.6, 95% CI: [0.3: 0.8]). The pass/fail global evaluation exhibited poor inter-rater reliability (Kappa: 0.105, 95% CI: [− 0.2:0.4]). On the survey, all participants wanted more expert-made videos of specific surgical techniques. Conclusions Despite a higher final OSATS score for the intervention group, self-directed learning by video failed to produce a statistically significant difference on the overall OSATS scores between the two groups in this small cohort.

Background Complete cytoreductive surgery (CRS) combined with hyperthermic intraperitoneal chemotherapy (HIPEC) is the only curative treatment for pseudomyxoma peritonei (PMP) arising from the appendix. High peritoneal carcinomatosis index (PCI) is associated with an increased risk of surgical complications. The objective of this study was to present the results of a planned two-step surgical strategy to decrease postoperative morbidity and improve resectability of patients with very high PCI. Methods All consecutive patients who underwent a planned two-step surgical approach for PMP between January 2012 and March 2020 were retrospectively included. This approach was offered for patients with low-grade PMP with PCI > 28 for which feasibility of a complete CRS in one operation was uncertain. The first surgery included a complete CRS of the inframesocolic compartment and omentectomy. HIPEC was delivered at the second surgery, after complete CRS of the supramesocolic compartment. Postoperative morbidity was assessed using the Clavien-Dindo classification and survival results were also collected. Results Eight patients underwent the two-step approach. The median PCI was 33 (29–39) and the median time between the two procedures was 111 days (90–212 days). One patient was deemed unresectable at the second surgery. The rate of major morbidity was 0% for the first step and 25% for the second step, with no mortality. Median follow-up was 53.8 months (3–73 months). Conclusion A two-step surgical management for low-grade PMP patients with very high PCI is safe and feasible, with acceptable postoperative morbidity and no compromise on oncological outcomes.

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