Abstract
ObjectivesPeritoneal metastases (PM) are relatively resistant to systemic chemotherapy, and data on histological response to therapy is rare. The aim of this study was to quantify the treatment response of PM after systemic chemotherapy.MethodsRetrospective monocentric cohort study of 47 consecutive patients with PM from gastrointestinal origin undergoing surgery (cytoreduction: CRS + Hyperthermic IntraPEritoneal Chemotherapy [HIPEC] or Pressurized IntraPeritoneal Aerosol Chemotherapy [PIPAC]) after prior systemic chemotherapy from 1.2015 to 3.2019. Tumor response was assessed using the 4-scale Peritoneal Regression Grading System (PRGS) (4: vital tumor to 1: complete response).ResultsPatients had a median of 2 (range: 1–7) lines and 10 (3–39) cycles of prior systemic chemotherapy. A median of four biopsies (range: 3–8) was taken with a total of 196 analyzed specimens. Twenty-four biopsies (12%) showed no histological regression (PRGS4), while PRGS 3, two and one were diagnosed in 37 (19%), 39 (20%), and 69 (49%) specimens, respectively. A significant heterogeneity was found between peritoneal biopsies in 51% patients. PRGS correlated strongly with peritoneal spread (PCI, p<0.0001), and was improved in patients with more than nine cycles of systemic chemotherapy (p=0.04). Median survival was higher in patients with PRGS < 1.8 (Quartiles one and 2) than higher (Q3 and Q4), but the difference did not reach significance in this small cohort.ConclusionsPRGS is an objective too to describe histological response of PM of GI origin after systemic chemotherapy. This response differs significantly between patients, allowing to distinguish between chemosensitive and chemoresistant tumors.
Highlights
As compared to liver metastasis, peritoneal metastases (PM) have a relatively limited response to systemic chemotherapy, and their prognosis remains poor in most disease entities [1]
The systematic use of peritoneal regression grading system (PRGS) for evaluating response of Peritoneal metastases (PM) to intraperitoneal chemotherapy was started in our institution immediately after it became available in June 2016, and was used prospectively since on a routine basis
Forty-seven consecutive patients were included for the analysis: 47 patients were treated with Pressurized Intra Peritoneal Aerosol Chemotherapy (PIPAC) and six with Heated Intra Peritoneal Chemotherapy (HIPEC)
Summary
As compared to liver metastasis, peritoneal metastases (PM) have a relatively limited response to systemic chemotherapy, and their prognosis remains poor in most disease entities [1]. Evaluation of treatment response tends to be difficult, as many patients have no target lesions allowing evaluation according to RECIST criteria [2]. One interesting alternative is the assessment by histological response, and a 4-grade standardized evaluation system, the peritoneal regression grading system (PRGS) that was proposed and validated recently. Intraperitoneal treatment modalities like Heated Intra Peritoneal Chemotherapy (HIPEC) and Pressurized Intra Peritoneal Aerosol Chemotherapy (PIPAC) offer access to tumor biopsies in patients who, in the majority, received a systemic treatment previously [5, 6]. The aim of this study was to quantify the histological response of PM after previous systemic chemotherapy. We aimed to determine a possible predictive value of PRGS after systemic chemotherapy. Our hypothesis was that a favorable PRGS would correlate with better overall survival
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