Peritoneal cytology in pancreatic cancer: a comprehensive review on prognostic stratification and clinical decision-making.

Microscopic evaluation of cells washed from the peritoneal cavity during surgery for gynecologic tumors is used to detect subclinical intraperitoneal metastases from these tumors. The prognostic significance of this test, however, has been questioned. Stressing histologic correlation and pitfalls in interpretation, we previously reported that the sensitivity of intraoperative peritoneal washing cytology was lower than was suggested earlier. This study evaluates the clinical utility of this test in the long-term follow-up of our patients. Staging (International Federation of Gynecology and Obstetrics [FIGO], 1971) and follow-up information was available for 355 unselected patients with primary tumors who had peritoneal washings performed during initial surgery at University Hospital-Stony Brook, NY, during the period from 1980 through 1989. There were 135 patients with endometrial carcinomas, 112 with ovarian carcinomas, 92 with cervical carcinomas, and 16 with borderline (i.e., of low malignant potential) ovarian tumors. The median follow-up of the patients was 57 months (range, 0-154 months). Follow-up data were obtained from the Tumor Registry at University Hospital-Stony Brook. Survival differences were determined by Kaplan-Meier analysis and were evaluated by two-tailed logrank test. RESULTS. Peritoneal washing cytology was positive at initial surgery for 120 (33.8%) of 355 patients, including 90 (80.4%) of 112 patients with ovarian carcinomas, five (31.2%) of 16 patients with borderline ovarian tumors, 17 (12.6%) of 135 patients with endometrial carcinomas, and eight (8.7%) of 92 patients with cervical cancers. For 203 patients with stage I tumors, the peritoneal cytology was positive in 29.4% of the patients with ovarian carcinomas, 18.2% with borderline ovarian tumors, 6.1% with endometrial carcinomas, and 5.2% with cervical carcinomas. By use of peritoneal histology as the standard, peritoneal cytology was highly specific (98.1%) but less sensitive (82.9%) in detecting intraperitoneal involvement. For patients with stage I tumors, 80.0% with ovarian carcinomas, 83.3% with endometrial carcinomas, and 100% with cervical carcinomas who showed positive cytology died of their cancer, compared with 25.0% with ovarian carcinomas, 13.0% with endometrial carcinomas, and 21.9% with cervical carcinomas who showed negative peritoneal cytology. Four (2.0%) patients with stage I tumors had positive peritoneal cytology but negative peritoneal histology. Of these patients, three (two with ovarian carcinoma and one with cervical carcinoma) died of their cancer, whereas one patient with a borderline ovarian tumor was free of disease at the last follow-up. Survival analysis indicated that peritoneal washing cytology stratified for stage provides better prognostic information for each primary cancer site studied than does stage alone. All patients with borderline ovarian tumors were alive at last follow-up, regardless of disease stage or peritoneal status. Regardless of FIGO stage, positive peritoneal washing cytology predicted poor prognosis for women with epithelial tumors of the genital tract, except for patients with borderline ovarian tumors. Patients in whom peritoneal cytology was the only evidence of intraperitoneal spread were few, but the disease in such patients was associated with poor outcome. Strict adherence to specialized cytologic criteria in peritoneal washing cytology allows for results that are highly predictive of survival. This information may be useful in stratifying women in therapeutic trials for treatment of genital tract carcinomas.

Tu1797 Validation of Immediate Peritoneal Washing Cytology Results in Pancreatic and Gastric Cancer

The prognostic value of positive intraoperative peritoneal cytology and lavage cytology, including the differences in their prognostic impact, in colorectal cancer is controversial. We aimed to investigate the prognostic values of positive peritoneal cytology and lavage cytology findings for colorectal cancer and compare their prognostic impact. We retrospectively evaluated 592 clinical stage II-IV colorectal cancer patients who underwent peritoneal cytology (n = 225) or lavage cytology (n = 367) between November 1993 and December 2018. The prognostic factors for cancer-specific survival were identified, and the differences in cancer-specific survival were examined between the patients. The cytology-positive rate was 10.8% (64/592), 17.8% (40/225), and 6.5% (24/367) in the overall, peritoneal cytology, and lavage cytology groups, respectively. Both positive peritoneal cytology (hazard ratio: 2.196) and lavage cytology (hazard ratio: 2.319) were independent prognostic factors. The peritoneal cytology-positive group showed significantly poorer cancer-specific survival than the cytology-negative group (5-year: 3.5% vs. 59.5%; 10-year: 3.5% vs. 46.1%, p < 0.001). Similar results were obtained for lavage cytology (5-year: 14.1% vs. 73.9%; 10-year: 4.7% vs. 63.5%, p < 0.001). The cancer-specific survival was not significantly different between the peritoneal cytology-positive and lavage cytology-positive groups (p = 0.058). Both positive peritoneal and lavage cytology were associated with poorer cancer-specific survival across all colorectal cancer stages. Positive peritoneal and lavage cytology are associated with worse cancer-specific survival in colorectal cancer. The prognostic impact was comparable between positive lavage and peritoneal cytology. Thus, cytology should be a standard assessment modality for colorectal cancer.

BackgroundThe prognostic impact of positive peritoneal lavage cytology on pancreatic cancer is unclear. Therefore, this study aimed to evaluate its impact in resectable pancreatic body and tail cancer.MethodsBetween January 2006 and December 2019, 97 patients with pancreatic body and tail cancer underwent peritoneal lavage cytology and curative resection at our institution. We analyzed the impact of positive peritoneal lavage cytology on clinicopathological factors and on the prognosis of pancreatic body and tail cancer.ResultsMalignant cells were detected in 14 patients (14.4%) using peritoneal lavage cytology. In these patients, the tumor diameter was significantly larger (p < 0.001) and anterior serosal invasion (p = 0.034), splenic artery invasion (p = 0.013), lympho-vessel invasion (p = 0.025), and perineural invasion (p = 0.008) were significantly more frequent. The R1 resection rate was also significantly higher in patients with positive peritoneal lavage cytology than in negative patients (p = 0.015). Positive peritoneal lavage cytology had a significantly poor impact on overall survival (p = 0.001) and recurrence-free survival (p < 0.001). This cytology was also an independent poor prognostic factor for recurrence (p = 0.022) and was associated with peritoneal dissemination and liver metastasis.ConclusionsPositive peritoneal lavage cytology is considered to be indicative of more systemic disease in patients with resectable pancreatic body and tail cancer than in patients with negative peritoneal lavage cytology. Early detection of pancreatic cancer before it develops micrometastases is important to improve prognosis, and CY+ patients require more intensive multimodality treatment than standard treatment for resectable pancreatic cancer.

96 Background: The presence of free cancer cells in the peritoneal cavity has been known as a poor prognostic factor in gastric cancer patients. Intraperitoneal (IP) paclitaxel (PTX) provides powerful local effects in the peritoneal cavity, and we previously reported the efficacy and safety of a regimen combining IP PTX with S-1/PTX in gastric cancer patients with peritoneal metastasis. This multicenter phase II study was conducted to evaluate the efficacy of IP PTX plus S-1/PTX for gastric cancer with positive peritoneal cytology. Methods: Eligibility criteria included pathologically confirmed gastric adenocarcinoma, intraperitoneal free cancer cells confirmed by peritoneal washing cytology, and no evidence of overt distant metastasis including macroscopic peritoneal metastasis. Patients were administered IP PTX 20 mg/m2, intravenous PTX 50 mg/m2 on days 1 and 8, and S-1 80 mg/m2/day on days 1-14, q3 weeks. The primary endpoint was the 1-year overall survival (OS) rate. Secondary endpoints were response rate, negative conversion rate on peritoneal cytology and safety. Results: Thirty eight patients were enrolled and fully evaluated for OS and toxicity. The median number of courses was 12.5 (range 2-35). The 1-year OS rate was 84.2% (95 % confidence interval, 68.2-92.6%). Of 3 patients with target lesions, partial response and stable disease were obtained in 2 and 1 patient(s), respectively. The peritoneal cytology findings converted from positive to negative in 36 (94.7 %) patients. The incidences of grade 3/4 hematological and non-hematological toxicities were 45 % and 26 %, respectively. The frequent grade 3/4 toxicities included neutropenia (23%), leukopenia (7%) and anemia (8%). Regarding adverse events related to IP port, 2 patients developed swelling around the port site. Conclusions: IP PTX with S-1/PTX was suggested to be a promising option for gastric cancer with positive peritoneal cytology through the clearance of cancer cells in the peritoneal cavity. Clinical trial information: UMIN000002850.

Context:The utility of peritoneal washing cytology in patients with gastroesophageal junction cancer has not been thoroughly evaluated.Aims:The study aimed to determine the incidence of free peritoneal tumor cells by peritoneal washing cytology before and after neoadjuvant chemotherapy using conventional cytopathological methods and immunohistochemical staining for the analysis of peritoneal washings.Settings and Design:A prospective study conducted at a single tertiary referral hospital.Materials and Methods:Patients with gastroesophageal junction cancer and without suspicion of intra- or extraabdominal metastases before the staging laparoscopy were prospectively and consecutively enrolled. Peritoneal washing cytology was performed at staging laparoscopy (primary cytology) and after neoadjuvant chemotherapy during robot-assisted or open resection (secondary cytology). Peritoneal fluid samples were analyzed by conventional cytology and an immunohistochemical panel.Results:Overall, 81 patients met the primary inclusion criteria. During primary cytology, positive cytology without overt metastases (C1M0) was detected in three patients (3.8%) while five patients (6.3%) had overt intra-abdominal metastases but negative cytology (C0M1). None of the patients with C1M0 underwent surgery due to extra-abdominal (n = 1) or intra-abdominal metastases (n = 2), and the overall survival was 4, 7, and 14 months. During secondary cytology, no patients with free peritoneal tumor cells were identified, but seven patients were classified as C0M1 (10.9%).Conclusions:The incidence of C1M0 was 3.8% and 0% before and after neoadjuvant chemotherapy, respectively in patients with gastroesophageal junction cancer. Free peritoneal tumor cells were not identified in several patients with intra-abdominal metastases suggesting that peritoneal washing cytology with conventional cytology and immunohistochemical staining lack sensitivity.

BackgroundPeritoneal dissemination of ovarian tumors is a major prognostic parameter in ovarian malignancies. Analysis of peritoneal washing cytology serves as a useful predictor of ovarian surface involvement and peritoneal metastasis even in the absence of clinical omental spread. The aim of the current study is to correlate peritoneal cytology with various histologic features of ovarian cancers in our setup.MethodsA total of 60 cases of ovarian tumors were included in the study that underwent total abdominal hysterectomy with bilateral salpingo-oophorectomy and omental and lymph node sampling during 2009 till 2014 at the Liaquat National Hospital, Karachi. Any free abdominal fluid was aspirated at the time of surgery. In the absence of free fluid, peritoneal washing was done with 50–100 ml of normal saline. Four cytospin preparations were done along with a cell block preparation. Correlation of peritoneal cytology with various histologic parameters was performed.ResultsOut of the 60 cases of ovarian tumors involved in the study, 56 were surface epithelial tumors, 2 germ cell tumors, and 2 metastatic carcinomas. The mean tumor size was 9.6 cm. Capsular invasion was seen in 61 % of the cases, and omental metastasis in 51 % of the cases. Serous carcinoma was found to have a significantly higher frequency of positive peritoneal cytology (76.9 %) compared to endometrioid and mucinous carcinomas (44 and 25 %, respectively). A significant positive correlation was seen between positive peritoneal cytology and capsular invasion and omental metastasis with a p value of <0.001.ConclusionsPositive peritoneal washing cytology has been implemented in ovarian cancer guidelines because of its prognostic significance in ovarian tumors. In addition to being an indicator of peritoneal metastasis, positive cytology also correlates with capsular invasion and histologic type in ovarian tumors. Therefore, it should always be used as an adjunctive tool in the surgical management of ovarian tumors.

Colorectal cancer (CRC) is among the most common carcinomas globally and a leading cause of cancer-related mortality. In Pakistan, it is the fifth most diagnosed malignancy and the fourth leading cause of cancer death. A significant number of patients present at advanced stages, limiting curative treatment options. Peritoneal metastasis is a recognized route of disease spread in CRC, following hepatic and pulmonary metastasis. While peritoneal washing cytology (PWC) is an established prognostic tool in gastric and gynecological cancers, its role in CRC remains unclear and underutilized. This study aimed to evaluate the association of peritoneal fluid cytology with tumor stage, histological subtype, and tumor differentiation in patients with CRC in a Pakistani population, with the secondary goal of evaluating its prognostic significance and potential therapeutic implications. We conducted a prospective observational study at the GI and HPB Department of SIUT Hospital, Karachi, from July to September 2025. A total of 83 patients aged 18-80 years with biopsy-proven colorectal adenocarcinoma, meeting specific inclusion criteria, were enrolled. Peritoneal lavage was performed intraoperatively before tumor manipulation, and cytological analysis of the fluid was conducted using standardized techniques. Cytology was deemed positive if malignant or atypical cells were identified. Statistical analysis was performed using SPSS version 26, with significance set at p < 0.05. Among the 83 patients, 71.1% were male, with a mean age of 41.3 ± 14.9 years. Rectal cancer was more prevalent (69.9%) compared to colonic cancer (28.8%). Signet-ring cell carcinoma was the most common histological subtype, found in 60.9% of patients, followed by mucinous adenocarcinoma (39.1%). Poorly differentiated tumors were observed in 43.3% of cases. Peritoneal cytology was positive in 14 patients (16.9%). Positive cytology was significantly associated with signet-ring cell carcinoma (p = 0.037) and advanced tumor stages, particularly stage IIIC (p = 0.0025). Stage IIIB also showed a trend toward significance (p = 0.380). Peritoneal fluid cytology was found to correlate with aggressive tumor histology and advanced staging in CRC, suggesting its potential as a prognostic marker. While not currently part of routine staging protocols for CRC, positive peritoneal cytology could identify patients at higher risk for recurrence and poor outcomes. These patients may benefit from intensified treatment approaches, including consideration for cytoreductive surgery (CRS) and hyperthermic intraperitoneal chemotherapy (HIPEC), as well as closer postoperative surveillance. Larger multicenter studies with long-term follow-up are warranted to confirm these findings and to explore the therapeutic implications of cytology-positive status in CRC. Hasan SR, Muhammad S, Khan S, et al. Colorectal Cancer: Correlating the Role of Peritoneal Fluid Cytology to Tumor Biology and Stage: A Prospective Study from Pakistan. Euroasian J Hepato-Gastroenterol 2025;15(2):141-145.

The prognostic significance of positive peritoneal cytology (PPC) in patients with early-stage endometrial cancer (Stage I/II) was disregarded by FIGO in 2009 classification, though FIGO recommends to collect peritoneal washings for cytology in all patients of endometrial carcinoma. To find out the association between positive peritoneal cytology and other prognostic factors of early-stage endometrial cancer and the influence of positive peritoneal cytology on survival of these patients. Primary objective—Association of positive peritoneal cytology with overall survival (OS) and disease-free survival (DFS). Secondary objective—Association of positive peritoneal cytology with other prognostic factors of early-stage endometrial cancer. Data were collected retrospectively from department of Gynecological oncology, Acharya Harihar Regional Cancer Center, Cuttack, India, between July 2009 and December 2017. Patients with stage I/II endometrial cancer who had undergone complete surgical staging procedure including pelvic lymphadenectomy were included. Comparison of pathological characteristics in patients with or without malignant cells in peritoneal cytology was done using univariate and multivariate analysis followed by survival analysis using Kaplan–Meier curves in these two groups, and the difference in survival was obtained by the log-rank test. Out of total 192 patients, 29 (15.1%) had positive peritoneal cytology. Among patients with positive peritoneal cytology, 27.6% patients had non-endometrioid histology like clear cell carcinoma and serous carcinoma of endometrium (P = 0.001). Similarly, 44.8% patients had Grade 3 histology, 51.7% patients had more than 50% myoinvasion, 48.3% patients had positive LVSI (lymphovascular space invasion) and 17.2% patients had stage II disease. Patients with positive peritoneal cytology had 17 months of lower disease-free survival (P < 0.0001) and 16 months of lower overall survival (P < 0.0004) compared to patients with negative peritoneal cytology. In multivariate analysis, positive peritoneal fluid cytology remained an independent prognostic factor for both disease-free survival (DFS) and overall survival (OS). Our study suggests that positive peritoneal cytology may be a potential prognostic factor in early-stage endometrial cancer owing to its significant association with other prognostic factors and its significant influence on both DFS (disease-free survival) and OS (overall survival).

IntroductionOvarian tumors remain one of the leading malignancies of the female genital tract, with a high mortality rate due to their insidious onset and lack of detection at an earlier stage. These tumors metastasize by direct extension into the neighboring pelvic organs; hence, the detection of peritoneal metastasis is valuable for staging and prognostic purposes. Peritoneal wash cytological analysis is an effective predictor of the involvement of the ovarian surface and peritoneal dissemination even in subclinical involvement of the peritoneum. The study aims to determine the significance of peritoneal wash cytology as a prognostic parameter and correlate it with various clinicohistological features.MethodsA retrospective study was conducted at the Department of Histopathology, Liaquat National Hospital, Karachi, Pakistan, between July 2017 and June 2022. During this period, all the cases of ovarian tumors (borderline and malignant) that underwent total abdominal hysterectomy with bilateral salpingo-oophorectomy and omental and lymph node sampling were included in the study. After opening the abdominal cavity, the free fluid present was aspirated immediately, the peritoneum was lavaged with 50-100 mL of warm saline, and samples were collected and sent for cytological analysis. Four cytospin smear slides and cell block preparation were prepared. The findings of peritoneal cytology were correlated with various clinicohistological features.ResultsA total of 118 cases of ovarian tumors were included in the study. Serous carcinoma was the most common sub-type (50.8%), followed by endometrioid carcinoma (14.4%), and the mean age at diagnosis was found to be 49.9±14.9 years. The mean tumor size was 11.2 cm. The majority of the cases of ovarian carcinoma were of high grade (78.8%), with capsular invasion present in 61% of cases. Positive peritoneal cytology was noted in 58.5% of cases, with omental involvement in 52.5% of cases. Serous carcinoma showed the highest frequency of positive cytology (69.6%) and omental metastasis (74.2%). Apart from tumor type, positive peritoneal cytology showed a significantly positive correlation with age, tumor grade, and capsular invasion.ConclusionBased on our study findings, we conclude that peritoneal wash cytology is a sensitive indicator of the peritoneal spread of ovarian carcinoma, with a significant prognostic value. Serous carcinomas, especially high-grade with capsular invasion, were found to be predictors of peritoneal involvement of ovarian tumors. Although we found smaller tumors to be associated with peritoneal disease more compared to larger ones, this most likely is attributed to tumor histology, as larger tumors were most commonly mucinous compared to serous carcinomas.

Positive peritoneal cytology in gastric cancer is classified as M1 disease by the 7(th) Edition of American Joint Committee on Cancer staging system. With the introduction of laparoscopy and peritoneal washing cytology in the staging of gastric cancer a new category of patients has been identified. These are patients with no macroscopic peritoneal metastases but with peritoneal cytology positive (P0C1). Prognosis and treatment of such patients represent a controversial issue. We evaluate the state of the art of staging system in gastric cancer and discuss standardisation in staging and treatment procedures. There is still a lack of uniformity in the use of laparoscopy with peritoneal cytology in clinical decision making and in the surgical treatment for gastric cancer. Survival of this patient subset remains poor. Multimodal therapies and new therapeutic strategies are required to improve the survival of these patients.

Peritoneal cytology in colorectal cancer: incidence and prognostic value

Positive peritoneal cytology is classified as M1 disease in gastric and pancreatic cancer. While peritoneal cytology is typically obtained by laparoscopic peritoneal lavage, this study sought to examine the feasibility and safety of performing this percutaneously, with monitored anesthesia care and in combination with other diagnostic procedures to condense and expedite the staging process. Patients with gastric or pancreatic cancer scheduled for laparoscopy with peritoneal lavage were prospectively enrolled to undergo intraoperative percutaneous peritoneal lavage prior to laparoscopic peritoneal lavage. Saline was infused through a percutaneously-inserted catheter and fluid was collected for peritoneal cytology. Three-quadrant washings collected during laparoscopy were also sent for peritoneal cytology. The primary outcome was to evaluate the sensitivity and specificity of percutaneous peritoneal lavage for detecting positive peritoneal cytology compared with the gold standard of laparoscopic peritoneal lavage, while the secondary outcome was to determine safety. Percutaneous peritoneal lavage was successfully performed in 70 of 76 patients (92%). Ten of 48 gastric cancer patients (21%) and three of 22 pancreatic cancer patients (14%) had positive percutaneous and laparoscopic peritoneal cytology. Two additional gastric cancer patients had positive laparoscopic peritoneal cytology only. Sensitivity and specificity of percutaneous peritoneal lavage compared with laparoscopic peritoneal lavage were 87% and 100%, respectively. No complications occurred with percutaneous peritoneal lavage. Percutaneous peritoneal lavage is a safe and effective minimally invasive alternative to laparoscopic peritoneal lavage for the diagnosis of metastatic gastric and pancreatic cancer. It is possible this can be utilized in an outpatient setting, such as during endoscopy, to allow for earlier diagnosis of M1 disease and decreased time to appropriate treatment.

The clinical significance of peritoneal lavage cytology for patients with gastric cancer is recognized, whereas that for patients with colorectal cancer remains controversial. The present study used a nationwide registry to clarify the prognostic significance of peritoneal lavage cytology in patients with colorectal cancer. We retrospectively analyzed factors associated with recurrence and survival in patients with T3-T4 colorectal cancer without distant metastasis taken from the nationwide registry of the Japanese Society for Cancer of the Colon and Rectum between 1984 and 1999. Among 34,554 patients in this study, not all of whom received peritoneal lavage cytology, 35 had positive peritoneal lavage cytology. Gender (P = 0.0004), tumor location (P < 0.0001), histological grade (P < 0.0001), depth of tumor invasion (P < 0.0001), lymph node metastasis (P < 0.0001) and peritoneal cytology (P = 0.015) were risk factors for peritoneal recurrence. Multivariate analysis revealed that tumor location (P < 0.0001), histological grade (P < 0.0001), depth of tumor invasion (P < 0.0001) and lymph node metastasis (P < 0.0001) were independent risk factors for peritoneal metastasis. Gender (P < 0.0001), tumor location (P < 0.0001), age (P < 0.0001), histological grade (P < 0.0001), depth of tumor invasion (P < 0.0001), lymph node metastasis (P < 0.0001) and peritoneal cytology (P = 0.0004) were independent prognostic factors according to the Cox proportional hazards model. Positive peritoneal lavage cytology was associated with poorer survival in patients with stage II and III colorectal cancer. Positive cytology might be a good indicator of candidates for intensive adjuvant chemotherapy. The benefit of intensive adjuvant chemotherapy for such patients should be validated in prospective trials.

Peritoneal metastases are the second most common site of involvement, following the liver, in pancreatic cancer. Thus, we performed peritoneal washing cytology at laparotomy to diagnose accurately the intraperitoneal spread of carcinoma cells to determine the appropriate therapy. Peritoneal washings were collected at laparotomy from 20 Japanese pancreatic carcinoma patients at Nagoya University Hospital between April 1993 and December 1994. From centrifuged deposits, we examined the cytology by three methods as follows. The first method was conventional cytology, including May-Grünwald and Giemsa, Papanicolaou, periodic acid-Schiff, and Alcian blue. The second method was immunocytochemical staining, using antibodies to carbohydrate antigen (CA19-9) and carcinoembryonic antigen. After extracting DNA from the remaining pellet, we studied the last method, detecting K-ras point mutation, by two-step polymerase chain reaction and restriction fragment length polymorphism analysis. In two cases, peritoneal metastases were macroscopically recognized, and the results of all three methods were positive. In the two other cases, where peritoneal dissemination was not macroscopically recognized, the judgments of conventional cytological study and detecting K-ras point mutation were negative. However, a few malignant cells were found by the immunocytochemical staining method. Judging from their clinical course, the positively stained cells were suggestive of malignancy. At present, the immunocytochemical staining method is the most sensitive of these three methods in peritoneal washing cytology. However, preserving DNA is suitable for repeated examination, and a modified method can be applied. If the sensitivity increases, the method of detecting K-ras has the potential to become the standard for peritoneal washing cytology in pancreatic cancer.