Mucin-Producing Lobular Breast Carcinoma Metastasis to an Ovarian Fibroma: Histopathological and Immunohistochemical Analysis of a Rare Case and Literature Review.

Breast cancer stands as the primary cause of cancer-related mortality among women worldwide, often presenting with distant metastases upon diagnosis. Ovarian metastases originating from breast cancer represent a range of 3-30% of all ovarian neoplasms. Case Report: Herein, we present the histopathological, histochemical, and immunohistochemical findings of a rare case involving mucin-producing lobular breast carcinoma metastasizing to an ovarian fibroma in an 82-year-old female previously diagnosed with lobular breast carcinoma. Histopathological examination of the excised tissues revealed a biphasic neoplasm characterized by tumor cells expressing AE-1/AE-3 cytokeratin, mammaglobin, GCDFP-15, inhibin, and calretinin. Positive mucin staining was observed using histochemical techniques, and reticulin fibers were demonstrated using the Gordon-Sweets technique. A final diagnosis of mucin-producing lobular breast carcinoma metastatic to a benign ovarian fibroma was rendered. Conclusion: The occurrence of metastatic breast carcinoma overlaid on an ovarian tumor represents a rare and diagnostically challenging scenario.

Synchronous Urinary Bladder Urothelial Carcinoma and Transitional Cell Carcinoma of the Ovary: A Case Report.

Transitional cell carcinoma (TCC) of the ovary is a rare subtype of epithelial ovarian tumours defined as a tumour composed of epithelial elements, histologically resembling urothelium and its neoplasms. Ovarian metastases from primary urinary tract carcinomas are rare. The differential diagnosis of primary TCC of the ovary versus metastatic bladder TCC is challenging because of histological similarity. We present the case of a 49-year-old premenopausal woman who was initially diagnosed with non-invasive papillary urothelial carcinoma of bladder (NIPUC) and after 2 years with a synchronous TCC of the ovary while being investigated for suspected relapse. She underwent a radical cystectomy, total hysterectomy, bilateral salpingo-oopharectomy, and pelvic lymph node dissection. The final diagnosis of synchronous NIPUC of the bladder and TCC of the ovary was made by histopathology and immunohistochemical studies.

Bilateral Ovarian Metastases of Hepatocellular Carcinoma Diagnosed with 18F-Fluorocholine PET/CT in a Patient with Endometriosis.

A 47-year-old woman with history of hepatocellular carcinoma was referred for 18F-fluorocholine PET/CT evaluation due to elevated alpha-fetoprotein. The examination showed several peritoneal uptakes and two nodular pelvic foci. Coelioscopic exploration allowed confirmation and resection of multiple peritoneal metastases from hepatocellular carcinoma while pelvic biopsies revealed endometriosis and endosalpingiosis. However, alpha-fetoprotein kept rising: subsequent 18F-fluorodesoxyglucose PET/CT exploration found no pelvic uptake, while 18F-fluorocholine PET/CT revealed intense tracer accumulation in the two pelvic masses corresponding to bilateral ovarian metastases of hepatocellular carcinoma. We highlight the importance of 18F-fluorocholine PET/CT in hepatocellular carcinoma especially in patients with confounding comorbidities such as endometriosis.

Unilateral ovarian metastasis from renal clear cell carcinoma.

INTRODUCTION AND IMPORTANCE: Ovarian metastases of renal origin are rarely reported in the literature and pose a diagnostic problem because they are usually diagnosed at a distance from the primary cancer. PRESENTATION OF CASE: We report a case of unilateral ovarian metastasis from clear cell renal cell carcinoma fifteen years after nephrectomy in a fifty-six-year-old patient who underwent surgery for an abdominopelvic mass. CLINICAL DISCUSSION: The diagnosis of ovarian metastases can be made at the same time as the diagnosis of the primary cancer or at a distance from it, with an interval ranging from a few months to years later. In the case of our patient, the ovarian metastasis was diagnosed fifteen years after the nephrectomy. CONCLUSION: Ovarian metastases are exceptional secondary localizations of renal cancer, they can be unilateral or bilateral, and are usually discovered several years after the renal tumor.

A propensity score-matched analysis of oncological outcome after systemic therapy for stage IV colorectal cancer: Impact of synchronous ovarian metastases.

The reported incidence of synchronous and metachronous ovarian metastases (OM) from colorectal cancer (CRC) is ~3.4%. OM from CRC are often considered sanctuary sites due to their lower sensitivity to systemic treatment. It has thus been hypothesized that the presence of OM decreases overall survival. Therefore, the purpose of our study was to evaluate the impact of synchronous OM on overall survival in female patients with stage IV CRC treated with systemic therapy alone with palliative intent. The present study used data from the Netherlands Cancer Registry and included female CRC patients with synchronous systemic metastases who were treated with systemic therapy between 2008 and 2018. A subsample was created using propensity score matching to create comparable groups. Propensity scores were determined using a logistic regression model in which the dependent variable was the presence of OM and the independent variables were the variables that differed significantly between both groups. Our study included 5253 patients with stage IV CRC that received systemic therapy. Among these patients, 161 (3%) had OM while 5092 (97%) had extra-ovarian metastases only. Three-year overall survival rates did not show a significant difference between patients with OM compared to patients without ovarian metastases. Moreover, the propensity score-matched analysis showed that the presence of OM in patients treated with systemic therapy for stage IV CRC disease was not associated with decreased 3-year overall survival. However, the results of the present study should be interpreted with caution, due to its observational character and used selection criteria.

Imaging of Metastatic Disease to the Ovary/Adnexa.

Ovarian metastases tend to arise in young women, either in patients with known cancer or as the first presentation of a previously occult extraovarian malignancy. Although imaging cannot always differentiate between secondary and primary ovarian neoplasms, and pathologic confirmation is generally required, it is important to recognize suggestive imaging features on pelvic MR imaging. Ovarian metastases are commonly described as bilateral, solid, heterogenous, and hypervascular. Features vary based on the tumor origin and histology. Knowledge of these features, plus the appropriate clinical context, can help guide radiologists to include metastases in their differential diagnosis for atypical adnexal masses.

Prediction of Chemotherapy Efficacy in Patients with Colorectal Cancer Ovarian Metastases: A Preliminary Study Using Contrast-Enhanced Computed-Tomography-Based Radiomics.

Ovarian metastasis (OM) from colorectal cancer (CRC) is infrequent and has a poor prognosis. The purpose of this study is to investigate the value of a contrast-enhanced CT-based radiomics model in predicting ovarian metastasis from colorectal cancer outcomes after systemic chemotherapy. A total of 52 ovarian metastatic CRC patients who received first-line systemic chemotherapy were retrospectively included in this study and were categorized into chemo-benefit (C+) and no-chemo-benefit (C-) groups, using Response Criteria in Solid Tumors (RECIST v1.1) as the standard. A total of 1743 radiomics features were extracted from baseline CT, three methods were adopted during the feature selection, and five prediction models were constructed. Receiver operating characteristic (ROC) analysis, calibration analysis, and decision curve analysis (DCA) were used to evaluate the diagnostic performance and clinical utility of each model. Among those machine-learning-based radiomics models, the SVM model showed the best performance on the validation dataset, with AUC, accuracy, sensitivity, and specificity of 0.903 (95% CI, 0.788-0.967), 88.5%, 95.7%, and 82.8%, respectively. All radiomics models exhibited good calibration, and the DCA demonstrated that the SVM model had a higher net benefit than other models across the majority of the range of threshold probabilities. Our findings showed that contrast-enhanced CT-based radiomics models have high discriminating power in predicting the outcome of colorectal cancer ovarian metastases patients receiving chemotherapy.

The utility of ultrasound-guided tru-cut biopsy in the diagnosis of occult breast carcinoma presenting as ovarian malignancy with multiple metastases: A case of unknown primary

@#This paper documents the utility of ultrasound-guided tru-cut biopsy in the diagnosis and subsequent management of a case of occult breast carcinoma presenting with multiple distant metastases in the absence of a primary breast lesion. She was initially diagnosed as primary ovarian malignancy with metastatic disease and subsequently underwent transvaginal ultrasound-guided tru-cut biopsy of the right ovarian mass. Histologic and immunohistochemical studies were consistent with a metastatic adenocarcinoma of breast origin. The patient underwent chemotherapy for primary breast carcinoma and has responded well.

Ovarian metastases in young women with colorectal cancer: a retrospective multicenter cohort study.

BACKGROUND AND PURPOSE: Previous studies indicated that approximately 3.4% of female colorectal cancer (CRC) patients are at increased risk of developing ovarian metastases (OM). It has been suggested that young women more frequently develop this form of metastatic disease. METHODS: This study evaluated, in 6 Dutch hospitals, the proportion of young women with CRC who developed OM. RESULTS: In a cohort of 200 young (age ≤ 55) women with CRC, the proportion of patients diagnosed with synchronous or metachronous OM was calculated. This study revealed that 5% (n = 10) of young female CRC patients developed ovarian metastases resulting in a 5-year overall survival rate of approximately 40%. Furthermore, six patients had concurrent peritoneal metastases, five patients had bilateral ovarian metastases, and five patients had synchronous metastases, while the median time of the occurrence of metachronous metastases (n = 5) was 19 months. CONCLUSION: This retrospective multicenter cohort study indicates that 5% of young women with CRC either present with or develop OM. This result appears to be clinically relevant and demonstrates the need for improved surveillance for young women diagnosed with CRC.

Outcomes of ovarian transposition in cervical cancer; an updated meta-analysis.

BACKGROUND: Cervical cancer is the most common indication for ovarian transposition in reproductive-age women. Ovarian transposition should be performed in premenopausal women undergoing pelvic irradiation to preserve ovarian function, and prevent early menopause. As women become more knowledgeable about their fertility options, it is still unclear who will benefit from the intervention. We updated our previous meta-analysis of ovarian function preservation, symptomatic ovarian cysts, and metastases to the transposed ovaries following ovarian transposition in cervical cancer patients to further guide current clinical practice. METHODS: A systematic search of Medline, Embase, Web of Science, and The Cochrane Library databases, dating from January 1980 to July 2021, was conducted. We computed the summary proportions of women who had ovarian function preservation, non-ovarian cyst formation and metastases to the transposed ovaries following ovarian transposition by random-effects meta-analysis and we explored study heterogeneity by type of radiotherapy. RESULTS: There were 29 publications reporting on 1160 women with cervical cancer who underwent ovarian transposition. In the group that underwent surgery alone, 91% of the women had preserved ovarian function (95% CI 83-100), 89% (95% CI 80-99) of women who did not develop ovarian cysts, and 99% (95% CI 1-5) of women who did not suffer metastases to the transposed ovaries. In the surgery ± brachytherapy (BR) group, the proportion of women with the preserved ovarian function was 93% (95% CI 76-113), 84% (95% CI 69-103) of women who did not develop ovarian cysts, and 99% (95% CI 82-120) of women who did not suffer metastases to the transposed ovaries. In the external beam pelvic radiotherapy (EBRT) ± BR ± surgery group, the proportion of women with the preserved ovarian function was 61% (95% CI 55-69), and 95% (95% CI 85-107) of women who developed ovarian cysts. There were no metastases to the transposed ovaries in that group. CONCLUSIONS: In women with cervical cancer, ovarian transposition offers a significant preservation of the ovarian function. Despite an expected incidence of ovarian cyst formation, it carries almost no risk for metastases to the transposed ovaries.

Retrospective Analyses of Complete Resection Combined with Systemic Chemotherapy and Targeted Therapy for Patients with Ovarian Metastases from Colorectal Cancer.

Background: The aim of the study is to evaluate clinical outcomes of patients with ovarian metastases from colorectal cancer (OM-CRC) treated with complete resection combined with chemotherapy and targeted therapy. Materials and Methods: Fifty female patients with OM-CRC who were treated in two different hospitals were categorized into three groups: 14 patients with OM-CRC received resection and chemotherapy combined with targeted therapy, 16 patients with OM-CRC only received chemotherapy combined with targeted therapy, and 20 patients with non-OM-CRC (NOM-CRC) received chemotherapy combined with targeted therapy. The primary outcomes, including overall survival (OS), the objective response rate (ORR), disease control rate (DCR), safety, and progression-free survival (PFS), were observed. Results: The ORR of OM-CRC was significantly lower compared with NOM-CRC (36.7% vs. 70.0%, p = 0.021), and the DCR of OM-CRC was also lower compared with NOM-CRC (76.7% vs. 90.0%, p = 0.229). The following chemotherapy and targeted therapy in the additional surgical resection of OM-CRC were positively associated with longer PFS and OS compared to no surgical resection (9.0 vs. 6.0 months and 21.0 vs. 15.0 months, respectively, p < 0.001), but the PFS and OS were best in patients with NOM-CRC (9.0 and 35.0 months). Improved OS was associated with R0 resection (23.0 vs. 17.0 months, p < 0.001). Multivariate analysis indicated that patients with well-differentiated pathology and unilateral ovarian metastasis had a better prognosis. Conclusion: Multidisciplinary treatment strategy, including systemic chemotherapy, targeted therapy, and complete surgery, may contribute to the prolongation of OS and be safe for treatment of OM-CRC.

Ovarian metastases of pancreatic adenocarcinoma: clinical presentation, role of surgery, and potential value of the mutational profile for the differential diagnosis with primary mucinous ovarian carcinoma.

BACKGROUND: Ovarian metastases (OM) of pancreatic adenocarcinoma (PA) (OM-PA) can mimic primary ovarian mucinous carcinoma (POMC) on imaging and histology. These metastases are often symptomatic and not highly chemosensitive, so that oophorectomy may be considered. AIMS: The aims of this study were to compare the characteristics of OM-PA and POMC, and discuss the role of surgery. PATIENTS AND METHODS: Clinical, imaging, and histological data of patients with OM-PA and POMC (2000-2017) in three tertiary centers were reviewed. Twenty-six genes were analyzed by next generation sequencing (NGS) on both primary PA and OM-PA. RESULTS: Twenty-two women with OM-PA (n = 13, 11 with surgical resection) or POMC (n = 9) were selected. OM-PA were smaller than POMC (p = 0.02); imaging, histological, and immunohistochemistry data did not clearly differentiate OM-PA from POMC in 12 of 22 cases (54%). Seven PA/OM-PA pairs were analyzed, and a concordant KRAS mutation was identified in all cases. In four OM-PA, concordant mutations were also found in TP53 (n = 3), SMAD4 (n = 1), MET (n = 1), and PDGFRA (n = 1) genes. The aim of oophorectomy in 11 OM-PA was for antalgic (n = 6) or curative (n = 5) intent. Pain improved in 4/6 of the former patients, but 2/6 had significant morbidity, and 2/6 died of rapid tumor progression. After oophorectomy, median progression-free and overall survivals were 6 (0-11) and 8 months (1-131), respectively. CONCLUSION: Analysis of mutation profiles in both primary PA and ovarian tumors, especially KRAS, can help to determine the pancreatic origin of OM-PA. Surgical resection of OM-AP in highly selected patients may improve pelvic symptoms but may also cause significant morbidity. The benefit to survival requires further studies.

Clinicopathological Characteristics and Prognostic Factors in Ovarian Metastases from Right- and Left-Sided Colorectal Cancer.

BACKGROUND: Secondary tumors of the ovary (STOs) account for 10-25% of all ovarian malignancies, including metastases from primary gynecological tumors. Colorectal cancer (CRC) has been recognized as one of the most common causes of STOs in Western countries. Despite it being well-known that CRC originating from the right versus left side of the colon/rectum differ substantially, there is a paucity of information regarding the effect of the primary tumor sidedness on the clinicopathological characteristics of STOs. METHODS: This retrospective, observational chart review study included patients with histologically confirmed STOs of CRC origin diagnosed between January 2000 and December 2019. The clinicopathological characteristics of STOs originating from left-sided and right-sided CRC were compared. Univariable and multivariable analyses employing elastic net Cox proportional hazard models were used to evaluate potential prognostic factors. Further, the role of imaging methods in STOs diagnostics was evaluated. RESULTS: Fifty-one patients with STOs of colorectal origin were identified. The primary tumor originated in the right and left colon/rectum in 39% and 61% of the cases, respectively. STOs originating from right-sided primary tumors were more frequently bilateral, associated with peritoneal carcinomatosis, had the ovarian surface affected by the tumor, and contained a mucinous component. The independent prognostic factors for overall survival in the whole cohort included: the presence of macroscopic residual disease after cytoreductive surgery, menopausal status, the application of systemic therapy, and the application of targeted therapy. In 54% of cases, the imaging methods failed to determine the laterality of the STOs correctly as compared to pathological reports and/or intraoperative findings. CONCLUSION: STOs originating from left-sided and right-sided CRC show distinct clinicopathological characteristics. Moreover, different metastatic pathways might be employed according to the primary tumor sidedness. Considering the discrepancies between radiological assessment and histopathological findings regarding the laterality of STOs, bilateral adnexectomy should be advised whenever feasible.

Ovarian metastases from colorectal cancer in young women: a systematic review of the literature.

BACKGROUND AND PURPOSE: In female colorectal cancer patients, a mean proportion of synchronous and/or metachronous ovarian metastases of 3.4% was described. Previous literature showed that young or premenopausal women (≤ 55 years of age) may be more frequently affected. Once ovarian metastases are diagnosed, the prognosis of the patient is generally dismal, with 5-year survival varying from 12 to 27%. The present study is aimed at determining the proportion of young or premenopausal women diagnosed with colorectal cancer who presented with or developed ovarian metastases by reviewing the current literature on this topic. METHODS: This review was performed by querying MEDLINE and EMBASE databases using a combination of terms: "colorectal neoplasms, colorectal cancer, ovarian neoplasms, Krukenberg tumor, young adult, young age, premenopause." Studies that indicated ovarian metastases, either synchronous or metachronous (or a combination of the two), in young women were retrieved and analyzed. RESULTS: The review identified 14 studies encompassing 3379 young or premenopausal female colorectal cancer patients. In this selected group of patients, a mean proportion of ovarian metastases of 4.6% [95% CI: 4.0;5.4] was found. CONCLUSIONS: This review showed that approximately one in twenty young female colorectal cancer patients will present with or develop ovarian metastases. Since outcome of this specific oncological pathology is often dismal, this finding is clinically relevant. It demonstrates the need to develop strategies to lower the incidence of ovarian metastases with adequate treatment and counseling of these patients.

Diagnostic workup for endometrioid borderline ovarian tumors (eBOT) requires histopathological evaluation of the uterus.

BACKGROUND: For young borderline ovarian tumor (BOT) patients, preservation of the uterus was incorporated as an accepted option into treatment guidelines. For the endometrioid subtype (eBOT) however, adequate histological evaluation is challenging and might be associated with synchronous endometrial disorders or misinterpreted as spread from uterine primaries. CASE PRESENTATION: We report the cases of two young patients with eBOT who underwent treatment according to current guidelines. In both cases, unexpected findings of invasive uterine carcinomas were established in final histopathological evaluation. CONCLUSIONS: This constellation highlights the challenging diagnostic workup of BOT and underlines that uterine curettage is indispensable for eBOT to exclude uterine primary tumors when fertility preservation is planned. Accordingly, we suggest to include this procedure into recommendations for diagnostic workup and to state the potential risk in treatment guidelines.

Prognostic factors for ovarian metastases in colorectal cancer patients.

PURPOSE: The aim of this study was to analyze prognostic factors for ovarian metastases (OM) in colorectal cancer (CRC) using data from a Chinese center. In addition, the study aimed at developing a new clinical scoring system for prognosis of OM of CRC patients after surgery. PATIENTS AND METHODS: Data of CRC patients with OM were collected from a single Chinese institution (n = 67). Kaplan-Meier analysis was used to evaluate cumulative survival of patients. Factors associated with prognosis of overall survival (OS) were explored using Cox's proportional hazard regression models. A scoring system to determine effectiveness of prognosis was developed. RESULTS: Median OS values for patients with or without surgery were 22 and 7 months, respectively. Size of OM, number of OM, peritoneal metastasis (PM), Peritoneal cancer index (PCI), and completeness of cytoreduction (CC) were associated with OS of patients through univariate analysis. Multivariate analysis using a Cox regression model showed that only CC was an independent predictor for OS. Three variables (the size of OM >15cm, PCI ≥ 10, and carcinoembryonic antigen (CEA) >30 ng/mL) assigned one point each were used to develop a risk score. The resulting score was used for prognosis of OS. CONCLUSION: Surgical treatment of metastatic sites is effective and safe for CRC patients with OM. CC-0 is recommended for improved prognosis. The scoring system developed in this study is effective for prediction of OS of patients after surgery.

Primary gastric squamous cell carcinoma with a bilio-gastric fistula and Krukenberg syndrome.

Primary squamous cell carcinoma of the stomach is a rare type of gastric malignancies. Diagnosis criteria are well defined but diagnosis is generally late being made at an advanced stage with metastases explaining its poor diagnosis.

Conversion surgery for metastatic gastric cancer at 2 years after initial diagnosis of cancer of unknown primary with metastasis of cervical lymph nodes and ovary: a case report.

BACKGROUND: Patients with stage IV gastric cancer have a poor prognosis despite improvements in intensive treatment regimens, including chemotherapy. Recently, conversion surgery has received much attention as it can provide long-term survival in stage IV gastric cancer patients who are responsive to chemotherapy. Herein, we describe the case of a patient who underwent conversion surgery for metastatic gastric cancer that was performed over 2 years after an initial diagnosis of cancer of unknown primary (CUP) with metastasis of the cervical lymph nodes and the ovary. CASE PRESENTATION: A 67-year-old woman with cervical lymphadenopathy was referred to our hospital. Computed tomography showed left cervical lymphadenopathy and bilateral ovarian enlargement. Endoscopic survey revealed no signs of malignancy in the upper or the lower gastrointestinal tract. Pathological findings after cervical lymphadenectomy revealed a signet-ring cell carcinoma and were suggestive of gastric cancer metastases. However, multiple evaluations yielded no evidence of gastric cancer and the patient was diagnosed with CUP. She was prescribed chemotherapy for gastric cancer and underwent bilateral oophorectomy after undergoing chemotherapy for 18 months. Pathologic analysis of oophorectomy tissue revealed findings identical to those seen in the cervical lymph nodes. At about 2 years after the initial diagnosis, an esophagogastroduodenoscopy revealed evidence of gastric cancer. We performed a distal gastrectomy with D2 lymphadenectomy. Her postoperative course was uneventful and she remains alive with no signs of disease recurrence at 3 months post-surgery. CONCLUSIONS: To the best of our knowledge, this is the first report describing successful conversion surgery for stage IV gastric cancer in a patient whose cancer was definitively diagnosed 2 years after an initial diagnosis of CUP.

Primary mucinous ovarian tumors vs. ovarian metastases from gastrointestinal tract, pancreas and biliary tree: a review of current problematics.

BACKGROUND: Making the distinction between primary mucinous and metastatic ovarian tumors is often difficult, especially in tumors with a primary source from the gastrointestinal tract, pancreas and biliary tree. The aim of the following paper is to provide an overview of the problematics, with a focus on the possibilities of the differential diagnosis at the macroscopic, microscopic and immunohistochemical level. MAIN BODY: The three main aspects of mucinous ovarian tumors are described in detail, including the comparison of the available diagnostic algorithms based on the evaluation of mostly macroscopic features, characterization of the spectrum of microscopic features, and a detailed analysis of the immunophenotype comparing 20 antibodies with the assessment of their statistical significance for differential diagnosis purposes. Specific features, including Krukenberg tumor and pseudomyxoma peritonei, are also discussed. CONCLUSION: Despite the growing knowledge of the macroscopic and microscopic features of ovarian mucinous tumors and the availability of a wide range of immunohistochemical antibodies useful in this setting, there still remains a group of tumors which cannot be precisely classified without close clinical-pathological cooperation.

Factors Prognostic for Peritoneal Metastases from Colorectal Cancer Treated with Surgery.

PURPOSE: To analysis factors prognostic for peritoneal metastases (PM) from colorectal cancer (CRC) treated with surgery using data from two sources and investigate the origin and effective treatment of ovarian metastases (OM). PATIENTS AND METHODS: Data from CRC patients with PM who had undergone surgery were collected from the Surveillance, Epidemiology, and End Results (SEER) database (n = 639) and a single Chinese institution (n = 60). Cumulative survival was evaluated by Kaplan-Meier analysis. Factors associated with overall survival (OS) and progression-free survival (PFS) prognosis were assessed using Cox's proportional hazard regression models. RESULTS: Median OS values for patients who underwent surgery were 19 and 32 months in the SEER database and Chinese center, respectively. Age was an independent predictor of OS in both datasets. Signet-ring cell cancer and perineural invasion were independent predictors of inferior OS only in the SEER dataset, while completeness of cytoreduction (CC) and peritoneal carcinomatosis index were independent predictors for OS and PFS only in the Chinese center. Median OS was 24 months in CRC patients with PM alone and 36 months in those with both PM and OM (p = 0.181). Further, median PSF in patients with PM alone was 10 months, while that in individuals with both PM and OM was 20 months (p = 0.181). CONCLUSION: Surgical treatment of the primary and metastatic sites is effective and safe for CRC patients with PM. CC-0 is recommended for improved prognosis. Moreover, OM should be recognized as a feature of PM, and cytoreductive surgery combined with hyperthermic intraperitoneal chemotherapy is beneficial for CRC patients with OM.