Overview
his prospective, single-center observational pilot study evaluates whether peritoneal histopathological growth patterns can be assessed on limited excisional biopsies obtained during staging laparoscopy in adults with suspected or confirmed colorectal peritoneal metastases. The study primarily evaluates agreement between the dominant histopathological growth pattern identified on laparoscopic biopsy and that identified on subsequent operative specimens.
One to three peritoneal deposits will be sampled during staging laparoscopy. When surgery proceeds, up to three peritoneal deposits will be collected from the operative specimen, preferably from corresponding Peritoneal Cancer Index regions. Two pathologists, blinded to clinical information, specimen timing, and each other's assessments, will independently estimate the proportions of pushing and infiltrating growth patterns.
Histopathological growth pattern findings will not be used to guide clinical management. Biopsy evaluability, interobserver reproducibility, interlesional heterogeneity, and exploratory associations with clinical and surgical characteristics will also be assessed.
Description
Peritoneal histopathological growth patterns (HGPs) describe the morphological interface between metastatic tumor deposits and the surrounding peritoneal tissue and may provide biological information that is not captured by conventional clinical or pathological variables. This prospective, single-center observational pilot study aims to determine whether peritoneal HGPs can be reliably assessed on limited biopsies obtained during staging laparoscopy and whether the dominant HGP identified on these biopsies agrees with that identified on subsequent cytoreductive surgery (CRS) specimens. Thirty adult patients with colorectal peritoneal metastases who are scheduled to undergo both staging laparoscopy and cytoreductive surgery, with or without hyperthermic intraperitoneal chemotherapy, will be prospectively enrolled.
During staging laparoscopy, one to three peritoneal deposits will be sampled using cold scissors. CRS will subsequently be performed within eight weeks, without interval systemic anticancer treatment. During CRS up to three additional peritoneal deposits will be collected, preferably from the same PCI regions or anatomical compartments as the laparoscopic samples. Two pathologists, blinded to clinical information, specimen timing, and each other's assessments, will independently estimate the proportions of pushing and infiltrating HGP at the tumor-peritoneum interface according to a prespecified histopathological standard operating procedure. The primary outcome will be patient-level agreement in dominant HGP classification between staging-laparoscopy biopsies and cytoreductive surgery specimens. Secondary outcomes will include biopsy evaluability, interobserver agreement, agreement in continuous HGP proportions, interlesional heterogeneity, and exploratory associations between HGP and primary-tumor characteristics, PCI, and completeness of cytoreduction. Overall survival and disease-free survival will be explored descriptively; however, the study is not powered to establish the prognostic value or clinical utility of HGP. HGP assessments will not be used to guide treatment decisions, which will remain based on standard multidisciplinary clinical evaluation.
Eligibility
Inclusion Criteria:
- Age ≥ 18 years
- Histologically confirmed colorectal adenocarcinoma
- Suspected or confirmed peritoneal metastases from colorectal cancer based on imaging or prior clinical evaluation
- Patients undergoing staging laparoscopy and/or cytoreductive surgery (CRS) ± hyperthermic intraperitoneal chemotherapy (HIPEC) as part of standard clinical care
- Availability of peritoneal metastasis tissue samples suitable for histopathological analysis
- Written informed consent provided for participation in the study
Exclusion Criteria:
- Age \< 18 years
- Peritoneal metastases originating from non-colorectal primary tumors
- Absence of available or adequate peritoneal metastasis tissue samples for histological growth pattern analysis
- Patients who decline or withdraw informed consent
- Patients unable to provide informed consent
