Background/Objectives: Liquid biopsy methods have gained prominence as minimally invasive tools to improve cancer treatment outcomes. Circulating tumor cells (CTCs) offer valuable insights into both primary and metastatic lesions. However, validating the CTC test results requires confirmation that the detected cells originate from cancer tissue. While studies have identified CTCs in colorectal cancer (CRC) patients using molecular markers, simultaneous validation of their cancer tissue origin remains unexplored. Methods: This study introduces a simple approach to detect adenomatous polyposis coli (APC) gene abnormalities alongside established CTC markers using a molecular imaging flow cytometer (MI-FCM). Given that APC gene abnormalities occur in 60–70% of CRC patients, their detection serves as strong evidence of cancer origin. Results: Our method achieved 92% concordance with DNA sequence analysis of tumor-derived cells. In a proof-of-concept study using 5 mL of whole blood from CRC patients, we observed a high frequency of cells exhibiting APC abnormalities, cytokeratin (CK), and vimentin (Vim) expression. Extending the study to 80 CRC patients across pathological stages I–IV confirmed CK and Vim as valid CTC markers. Three distinct cell populations were identified in blood: CK+/Vim−, CK+/Vim+, and CK−/Vim+. CTC number and frequency increased progressively with cancer stage. Conclusions: This is the first report demonstrating CK and Vim as effective markers for direct CTC detection in CRC patients. Our findings provide evidence-based validation of CTC markers, offering new insights and advancing approaches for patient care.

Background/Objectives: Menstrual blood, a periodic uterine discharge, represents a non-invasive source for an indication of the functional status of the endometrium. While menstrual blood-derived stem cells have been extensively characterized and menstrual blood is considered a diagnostic material for the analysis of gynecologic pathology in research studies, it is not routinely used in clinical settings. To develop novel noninvasive diagnostic tools for endometrial status assessment, we aimed to characterize the morphological and molecular markers of menstrual blood. Methods: Menstrual blood samples were obtained from healthy volunteers and characterized macroscopically and microscopically using smears (May-Grunwald-Giemsa staining), confocal microscopy, and imaging flow cytometry (cluster of differentiation [CD]90, CD45, fibrin). Clot dissociation was performed to analyze the cellular composition of clots. Results: We morphologically characterized menstrual blood cells and identified three uterine-derived cells and cell cluster types (endometrial stromal, endometrial epithelial, and vaginal epithelial). Additionally, we confirmed the specificity of CD90 for endometrial stromal cell populations, which were separately characterized in the supernatant and menstrual blood clots using light and confocal microscopy, and we analyzed the composition of the menstrual blood supernatant and dissociated clots using imaging flow cytometry. Conclusions: The results of this study may serve as a foundation for the development of new non-invasive diagnostic tools for endometrial pathology for the potential support or replacement of highly invasive procedures, such as diagnostic dilation and curettage.