5-Nitro-2,4-Dichloropyrimidine as an Universal Model for Low-Energy Electron Processes Relevant for Radiosensitization.

We report experimental results of low-energy electron interactions with.

HPV-positive Squamous Cell Carcinoma of the Larynx, Oral Cavity, and Hypopharynx: Clinicopathologic Characterization With Recognition of a Novel Warty Variant.

Human papillomavirus (HPV) is a principal driver for most oropharyngeal squamous cell carcinomas (OPSCCs), where it is strongly associated with improved survival. HPV is much less frequently detected in squamous cell carcinomas arising in nonoropharyngeal sites (non-OPSCCs), and its pathogenic role and prognostic value in these tumors is unclear. We evaluated the clinicopathologic features of 52 non-OPSCCs considered HPV-positive based upon p16 immunohistochemistry and direct HPV detection using RNA in situ hybridization (ISH), DNA ISH, or real-time DNA polymerase chain reaction. The HPV-positive non-OPSCCs were from the larynx (n=27), oral cavity (n=21), and hypopharynx (n=4). While most cases (n=34, 65%) showed classic histologic features of HPV-positive OPSCC, including endophytic growth, minimal keratinization, and hyperchromatic nuclei without koilocytic changes, a subset (n=13, 25%) were characterized by exophytic growth, exuberant surface hyperkeratosis and parakeratosis, marked nuclear pleomorphism, and prominent koilocytic atypia. These antithetical features were highly reminiscent of the warty variant of HPV-positive squamous cell carcinoma described in anogenital sites. Compared with tumors without warty features, the warty tumors presented at lower stage and were not associated with lymph node metastasis, local recurrence, or distant spread (4 y disease-free survival of 100% vs. 66%, P=0.069). The presence of transcriptionally active HPV as detected by RNA ISH suggests a pathogenic role for HPV in these nonoropharyngeal sites. While most HPV-positive non-OPSCCs are morphologically similar to their tonsillar counterparts, this study highlights a previously unrecognized warty variant that may be associated with a highly favorable clinical outcome.

Human papillomavirus in laryngeal and hypopharyngeal lymphoepithelial carcinoma.

The involvement of human papillomavirus (HPV) in laryngeal and hypopharyngeal lymphoepithelial carcinoma was investigated in a series of ten cases (seven laryngeal and three hypopharyngeal), retrieved from the files of three tertiary hospitals in the 2000-2017 period, through polymerase chain reaction with SPF10 primers and INNO-LiPA HPV Genotyping Extra II (Innogenetics). Epstein-Barr virus (EBV) was tested in all cases with in situ hybridization INFORM EBER Probe (Ventana Medical Systems). p16 and p53 expression were immunohistochemically analyzed. Calculated annual incidence was 0.013/100,000, and prevalence was 0.2% of laryngeal and hypopharyngeal carcinomas. All cases were EBV negative. HPV was detected in five cases, three of which also overexpressed p16. HPV16 was detected in four cases, and HPV58 in one case. Five cases were HPV negative, only one of these five overexpressed p16. No recurrence was observed in nine cases during follow-up. The 5-year disease-specific-survival rate was 100%. Mean overall survival was 87 months. Lymphoepithelial carcinoma of the larynx and hypopharynx are not related to EBV. Simultaneous HPV+/p16+ is consistent with HPV causation in a fraction of laryngeal and hypopharyngeal lymphoepithelial carcinomas.

PD-L1 Immunohistochemistry Assay Concordance in Urothelial Carcinoma of the Bladder and Hypopharyngeal Squamous Cell Carcinoma.

Programmed death ligand-1 (PD-L1) immunohistochemistry is used to guide treatment decisions regarding the use of checkpoint immunotherapy in the management of urothelial carcinoma of the bladder and hypopharyngeal (HP) squamous cell carcinoma. With increasing PD-L1 testing options, a need has arisen to assess the analytical comparability of diagnostic assays in order to develop a more sustainable testing strategy. Using tissue microarrays, PD-L1 expression in tumor cells (TCs) and immune cells (ICs) was manually scored in 197 cases and 27 cases of bladder and HP cancer, respectively. Three commercial kits (Ventana SP263, Ventana SP142, Dako 22C3) and 1 platform-independent test (Cell Signalling Technologies E1L3N) were utilized. Across the 3 commercially available clones, 14% and 74% of urothelial carcinomas were positive and negative, respectively, whereas 7% and 78% of HP carcinomas were positive and negative, respectively. Twelve percent of bladder and 15% HP cases showed discrepant PD-L1 classification results. Regardless of the scoring algorithm used, E1L3N provided comparable PD-L1 staining results. Fleiss' kappa and intraclass correlation coefficient (ICC) analyses demonstrated substantial agreement among all antibody clones (k=0.639 to 0.791) and excellent reliability among SP263, 22C3, and E1L3N antibodies (ICC, 0.929 to 0.949) in TC staining. Compared with the other 3 clones, SP142 TC staining was lower with only moderate correlation (ICC, 0.500 to 0.619). Generally, the reliability of immune cell staining was lower compared with TC staining (ICC, 0.519 to 0.866). Our results demonstrate good analytic comparability of all 4 antibodies. The results are encouraging and support growing optimism in the pathology and oncology communities concerning strategies in PD-L1 assay use.

[The significance of circulating tumor cells in head and neck squamous cell carcinoma: a preliminary study].

Objective: To investigate the significance of circulating tumor cells (CTC) in squamous cell carcinoma of the head and neck (HNSCC). Methods: Twenty-four patients with HNSCC treated between October 2016 and July 2017 in our department were selected (experimental group), including 23 males and 1 females, aged 47-81 years. There were 14 cases of squamous cell carcinoma of larynx and 10 cases of hypopharynx, including I-Ⅱ stage (5 cases) and Ⅲ- Ⅳ stage (19 cases). All patients were primary and/or relapsed after treatment. Nine healthy volunteers were selected as control group. A novel in vivo capture technique (CellCellector system) was used to detect CTC. SPSS23.0 was used for statistical analysis. Results: The total capture rate of CTC in patients with HNSCC before treatment was 70.8% (17/24), with 40% (2/5) for patients at I-Ⅱ stage, and 78.9% (15/19) for patients at Ⅲ- Ⅳ stage, and was 0 in patients of control group. The total capture rate of CTC in patients with HNSCC after treatment was 50% (8/16). There was no significant correlation between CTC and age, sex, location of tumor or lymph node metastasis (P>0.05). CTC was related to tumor staging and tumor differentiation (P<0.05). The positive rate of EGFRVⅢ in CTC was 26.3% (5/19). Conclusions: The CellCollector system is a very efficient way of detecting CTC, and CTC plays an important role in the occurrence, progression and metastasis of HNSCC.

Selenium-binding protein 1 in head and neck cancer is low-expression and associates with the prognosis of nasopharyngeal carcinoma.

BACKGROUND: Selenium-binding protein 1 (SELENBP1) expression is reduced markedly in many types of cancers and low SELENBP1 expression levels are associated with poor patient prognosis. METHODS: SELENBP1 gene expression in head and neck squamous cell carcinoma (HNSCC) was analyzed with GEO dataset and characteristics of SELENBP1 expression in paraffin embedded tissue were summarized. Expression of SELENBP1 in nasopharyngeal carcinoma (NPC), laryngeal cancer, oral cancer, tonsil cancer, hypopharyngeal cancer and normal tissues were detected using immunohistochemistry, at last, 99 NPC patients were followed up more than 5 years and were analyzed the prognostic significance of SELENBP1. RESULTS: Analysis of GEO dataset concluded that SELENBP1 gene expression in HNSCC was lower than that in normal tissue (P < 0.01), but there was no significant difference of SELENBP1 gene expression in different T-stage and N-stage (P > 0.05). Analysis of pathological section concluded that SELENBP1 in the majority of HNSCC is low expression and in cancer nests is lower expression than surrounding normal tissue, even associated with the malignant degree of tumor. Further study indicated the low SELENBP1 expression group of patients with NPC accompanied by poor overall survival and has significantly different comparing with the high expression group. CONCLUSION: SELENBP1 expression was down-regulated in HNSCC, but has no associated with T-stage and N-stage of tumor. Low expression of SELENBP1 in patients with NPC has poor over survival, so SELENBP1 could be a novel biomarker for predicting prognosis.

DCE-MRI biomarkers for monitoring an anti-angiogenic triple combination therapy in experimental hypopharynx carcinoma xenografts with immunohistochemical validation.

BACKGROUND: Novel anti-angiogenic treatments are increasingly complementing established cancer therapy strategies in head and neck tumors. Contrast-enhanced magnetic resonance imaging (MRI) can be applied for early and non-invasive therapy monitoring by non-invasive quantitative assessment of tumor microcirculation as in vivo imaging biomarkers of therapy response. PURPOSE: To monitor the anti-angiogenic effects of a novel combination therapy on experimental head and neck squamous cell carcinomas (HNSCC) with dynamic contrast-enhanced (DCE)-MRI. MATERIAL AND METHODS: Athymic rats (n = 18) with subcutaneous HNSCC xenografts were investigated by DCE-MRI before and after 7 days of a daily triple therapy regimen combining the COX-II-inhibitor celecoxib, the matrix-metalloproteinase-inhibitor GM6001, and the uPA-inhibitor upamostat. Quantitative measurements of tumor blood flow (tBF), tumor blood volume (tBV), and permeability-surface area product (PS) were calculated and validated by immunohistochemistry. RESULTS: Mean tBF and tBV in triple-therapy animals decreased significantly from day 0 to day 7 (tBF, 41.0 ± 14.2 to 20.4 ± 5.7 mL/100 mL/min; P < 0.01; tBV, 17.7 ± 3.9 to 7.5 ± 3.3%; P < 0.01). No significant effects on PS were observed in either group (P > 0.05). Immunohistochemical analysis showed a significantly lower tumor vascularity in the therapy group than in the control group (CD31), significantly fewer Ki-67+ proliferating tumor cells and significantly more Capase-3+ apoptotic tumor cells (P < 0.05). Significant (P < 0.05) correlations were observed between tBF/tBV and CD31 (tBF, r = 0.84; tBV, r = 0.70), tBV and Ki-67 (r = 0.62), as well as tBF and caspase-3 (r = -0.64). CONCLUSION: DCE-MRI may be a suitable tool for the non-invasive monitoring of the anti-vascular effects of this innovative triple therapy regimen with potential for clinical translation.

p16 not a prognostic marker for hypopharyngeal squamous cell carcinoma.

OBJECTIVE: To investigate the prognostic significance of p16 in patients with hypopharyngeal squamous cell carcinoma (HPSCC) and to evaluate the relationship between p16 and human papillomavirus (HPV). Unlike in oropharyngeal SCC (OPSCC), the prognostic significance of p16 in HPSCC and its association with HPV is unclear. DESIGN: Retrospective medical chart review. SETTING: University tertiary referral center. PATIENTS: A total of 27 patients with HPSCC treated with definitive radiation therapy between 2002 and 2011 whose tissue was available for immunohistochemical analysis. INTERVENTIONS: Twenty-two patients were treated with chemoradiation, and 5 with radiation alone. All tumor biopsy specimens were analyzed for p16 and, when sufficient tissue was available, for HPV DNA. MAIN OUTCOME MEASURES: Overall survival (OS), locoregional control (LRC), disease-free survival (DFS), and laryngoesophageal dysfunction-free survival (LEDFS) were analyzed according to p16 status. RESULTS: Findings for p16 were positive in 9 tumors and negative in 18 tumors. Median follow-up was 29.3 months. There was no significant difference in OS, LRC, DFS, or LEDFS for patients with p16-positive vs p16-negative tumors. Only 1 of the 19 tumors tested for HPV was found to be HPV positive. When used as a test for HPV, p16 had a positive predictive value of 17%. CONCLUSIONS: In contrast to OPSCC, p16 expression in patients with HPSCC had a low positive predictive value for HPV and did not predict improved OS, LRC, DFS, or LEDFS. Thus, for HPSCC, p16 is not a prognostic biomarker. Caution must be taken when extrapolating the prognostic significance of p16 in patients with OPSCC to patients with head and neck SCC of other subsites.

Mucosal large cell neuroendocrine carcinoma of the head and neck regions in Japanese patients: a distinct clinicopathological entity.

BACKGROUNDS: Large cell neuroendocrine carcinoma (LCNEC) is well-known as a lung cancer subtype. This study assessed the prevalence of head and neck mucosal LCNEC (M-LCNEC). METHODS: M-LCNEC was studied clinically, histologically and immunohistochemically. RESULTS: Of 814 surgically resected cases of mucosal head and neck carcinoma, only eight cases (0.98%; all men, mean age 64.6 years) were rediagnosed as M-LCNEC. They occurred in the oropharynx (n=3), larynx (n=4) and hypopharynx (n=1). Seven of the cases had regional lymph node metastases and four resulted in death. Histologically, M-LCNEC had a sheet-like trabacular organoid growth pattern of relatively large basaloid cells in which central necrosis, rosette formation, peripheral palisading and high mitotic figures were evident. M-LCNEC was immunopositive for two or three neuroendocrine markers (CD56, chromogranin-A and synaptophysin). All cases showed high proliferative activity. CONCLUSION: M-LCNEC in the head and neck regions is a distinct histopathological entity whose positivity for neuroendocrine markers makes its diagnosis important. As about half of the patients died of the disease, M-LCNEC has a relatively poor prognosis.

[Basaloid squamous carcinoma with a spindle cell component and osseous metaplasia presenting as a polyp of the hypopharynx]. / Carcinome épidermoïde basaloïde et à cellules fusiformes avec métaplasie osseuse se présentant comme un polype de l'hypopharynx.

We report a case of basaloid squamous carcinoma with a spindle cell component of the hypopharynx, in a 61-years-old-man. An excisional biopsy of a pedonculated and polypoid tumour was performed by endoscopy. The histologic examination revealed a biphasic tumour with both a basaloid carcinomatous and a spindle cell component. Focally, osseous metaplasia was seen. The spindle cell component demonstrated immunoreactivity with the p63 epithelial marker. The patient was treated with chemotherapy followed by radiotherapy. The patient has been free of disease for one year. It's the ninth case reported in the literature of a biphasic carcinoma with both a basaloid squamous and a spindle cell component and the first case with osseous metaplasia.

Clinicopathological features of atypical lipomatous tumors of the laryngopharynx.

Atypical lipomatous tumor (ALT) of the laryngopharynx is rare. Here we report five cases to demonstrate their clinicopathological features. The patients were four males and one female, aged 41 to 69 years (median 53.6 years). All tumors (two in the hypopharynx and three in the larynx) presented as a slowly growing, painless mass. Symptoms included dysphagia (2/5), dysphonia (3/5), and the feeling of a foreign body in the throat (5/5). Tumors were well circumscribed or focally infiltrative, ranging from 2.0 to 5.0 cm (median, 3.4 cm) in size, and microscopically showed the typical features of lipoma-like ALT. Immunohistochemically, tumor cells were stained with S-100, vimentin, murine double minute 2 (MDM-2), and cyclin-dependent kinase 4 (CDK4). Two patients had local tumor recurrences at 6 and 14 months after initial surgery during follow-up. ALT of laryngopharynx is an indolent tumor. Immunohistochemical staining for MDM-2 and CDK4 is helpful in pathological diagnosis.

Spindle basaloid squamous carcinoma of the upper aerodigestive tract: immunohistochemical and clinicopathological study of three cases.

We describe the clinicopathological and immunohistochemical features of three spindle (sarcomatoid) basaloid squamous carcinomas in three men aged 73, 69, and 59 years with a history of tobacco and alcohol abuse. Two tumors were located in the hypopharynx and one was located in the nasal cavity. The three tumors have a pedunculated polypoid appearance. Histologically, they were composed of conventional basaloid squamous carcinomas with extensive malignant spindle cell proliferation, comprising more than 50% of the tumor. The sarcomatoid component demonstrated immunoreactivity with one or more epithelial markers. One case in addition expressed CD99 and Bcl-2 and was originally diagnosed as monophasic synovial sarcoma; however, a subsequent biopsy disclosed basaloid squamous cell carcinoma with sarcomatoid stroma. Two patients were treated with surgery and radiation whereas one refused therapy. The patients were alive 14 (case patient 1), 10 (case patient 2), and 8 (case patient 3) months after diagnosis. In the absence of evidence from immunohistochemical or electron microscopy studies, a polypoid malignant spindle cell tumor of a mucosal surface of the upper aerodigestive tract should be considered a sarcomatoid carcinoma until proven otherwise. The type of epithelial component would determine the subtype of sarcomatoid carcinoma.

Prognostic impact of the epidermal growth factor receptor levels for patients with larynx and hypopharynx cancer.

The aim of this study was to analyse prognostic factors for disease free interval (DFI) and overall survival (OS) among patients with larynx and hypopharynx cancer requiring a total laryngectomy. Three groups of patients were studied according to the type of treatment they received. Fifty-eight patients had total laryngectomy, 71 patients had organ preservation treatment including induction chemotherapy followed by exclusive radiotherapy, 26 patients received induction chemotherapy followed by salvage total laryngectomy. The studied potential prognostic factors were age, gender, performans status, primary tumor localization, T status, N status, tumor volume and tumoral EGFR level (fmol/mg protein). The multivariate analysis showed that both N status and tumor volume were significant for DFI and OS. EGFR level was significant only for patients treated by induction chemotherapy and exclusive radiotherapy (p = 0.05 and 0.05 for DFI and OS length, respectively). Among this group, patients with tumor EGFR levels lower and higher than 100 fmol/mg protein had 53% versus 22% and 51% versus 18% 5-year of DFI and OS rates, respectively (Log rank test: p = 0.001 and 0.0001). EGFR determination appears to be a powerful prognostic parameter for patients treated by induction chemotherapy followed by exclusive radiotherapy. Laryngectomy seems to erase the prognostic impact of EGFR expression. These results profile the use of EGFR targeting therapy for this category of patients.

P105 as a prognostic indicator in patients irradiated for locally advanced head-and-neck cancer: a clinical/laboratory correlative analysis of RTOG-9003.

PURPOSE: In a previous retrospective study, p105 AD, a proliferation-associated nuclear antigen density (AD), was found to be an independent prognostic factor for patients irradiated for locally advanced head-and-neck cancer. We sought to confirm this finding by analyzing patients entered on RTOG 9003, a Phase III randomized trial of altered fractionation radiotherapy. METHODS AND MATERIALS: Paraffin blocks of pretreatment biopsies of the primary tumor of patients with Stage III or IV squamous cell carcinoma of the oral cavity, oropharynx, or supraglottic larynx, or Stage II squamous cell carcinoma of the hypopharynx or base of tongue entered on RTOG 9003 were prospectively collected at patient entry. From these paraffin blocks, areas of tumor were selected based on histologic examinations and sectioned. Nuclear suspensions were then prepared and processed for p105 antibody and DNA staining. Flow cytometric quantification of p105 labeling indices and DNA content were then performed for correlation with local-regional control and survival. RESULTS: Paraffin blocks of tumor biopsies from 457 of 1073 patients entered were available for p105 determination. There was no significant difference in pretreatment characteristics between patients who had paraffin blocks available or not available. The median (range) of p105 labeling index (LI-C), p105 labeling index of cells in S phase (p105 LI-S), and p105 AD were 56 (range: 6-99), 8.255 (range: 0.913-23), and 67 (range: 5-364), respectively. Multivariate analysis of prognostic factors showed that T stage, N stage, Karnofsky performance status, and fractionation schedule were significant for local-regional control (p < 0.0001, 0.0011, <0.0001, and 0.007, respectively) and T stage, N stage, Karnofsky performance status, and tumor grade were significant for survival (p = 0.018, 0.002, <0.0001, and 0.0058, respectively). Neither p105 LI-C nor p105 LI-S nor p105 AD nor DNA ploidy was significant for local-regional control or survival. CONCLUSION: p105 labeling indices, antigen density, and DNA ploidy do not predict the outcome of patients irradiated for advanced squamous cell carcinomas of the head and neck.

Distribution and prognostic significance of cell cycle proteins in squamous carcinoma of the larynx, hypopharynx and adjacent epithelial hyperplastic lesions.

Alterations of cell cycle proteins contribute to the development and biological behaviour of malignant tumours. We evaluated the distribution and prognostic significance of immunohistochemically detected proteins p53, p21, Rb, and cyclin D1 in 101 laryngeal and hypopharyngeal squamous cell carcinomas (SCC) and adjacent epithelial hyperplastic lesions (EHL). Protein expression was correlated with tumour grade and stage. Varying patterns of protein expression were found in SCC. A significant correlation (p<0.05) was found between Rb expression and tumour grade. Different grades of EHL exhibited randomly distributed p53 and cyclin D1 positive cell clusters with no association to the pattern of their expression in SCC. Our study demonstrated derailment of cell cycle regulation in almost all cases of SCC of the larynx and hypopharynx. However, only cyclin D1 expression had an independent prognostic value for cancer-specific survival. The results also suggest that Rb gene inactivation, although rare, might be more important in the development of SCC than previously thought.

The predictive value of p53, Ki-67 and angiogenetic factors in primary hypopharyngeal carcinoma.

To evaluate the predictive role of the oncogene p53, the proliferating marker Ki-67, angiogenic factors platelet-derived endothelial cell growth factor/thymidine phosphorylase (PD-ECGF/dThdPase) and vascular endothelial growth factor (VEGF) in primary hypopharyngeal carcinoma, we immunohistochemically studied a series of 84 primary hypopharyngeal carcinoma patients who were treated at the Department of Otolaryngology of Kurume University Hospital between 1990 and 1997. The correlation of each score according to the intensity and percentage of the labeled cells with the TNM stage, histological grade, metastasis and survival status was analyzed. The positive rate of p53 was 52.4%. The percentages of Ki-67 labeled cells in patients with or without metastasis showed a significant difference (p = 0.011). VEGF also showed a significant difference between the live and death groups (p < 0.05) and also among the differentiation group (p < 0.05). A statistically significant correlation was also seen between the score of Ki-67 and VEGF (r = 0.438, p < 0.001) or the score of Ki-67 and PD-ECGF (r = 0.259, p < 0.001), respectively. In conclusion, the present study suggests that a correlation exists between proliferating and angiogenesis, and VEGF and Ki-67 are thus considered to be possible prognostic discriminators in hypopharyngeal carcinoma.

Metallothionein immunoreactivity in head and neck carcinomas; special reference to clinical behaviors and chemotherapy responses.

Metallothionein (MT), has selectively binding affinity for heavy metal ions and over expression of MT has a potential against resistance for CDDP anticancer agents and radiation treatment. The role of MT immunoreactivity of squamous cell carcinoma in oral and pharyngeal regions (n = 28) and in the maxillary sinus region (n = 3) was evaluated for distribution patterns of MT and clinicopathologic behaviors. All the sections were examined in 400x and counted for MT positive cells over 5 fields of tumor growing foci. MT immunoreactivity was expressed in both tumor cell cytoplasm and nuclei, and showed heterogeneous localization in tumor epithelial cells and in the stroma. Immunohistochemical localizations showed mosaic patterns as the highest MT staining tumor cells intermingled with negative or low staining cells in neoplastic foci, and in stromal cells. Histiocytic and fibrocytic cells in both peripheral and interstitial stromas were also not stained homogeneously. In oral and pharyngeal carcinomas (n = 28), MT positive cell index in treated cases (n = 11) was 17.85% and that in non treated tumors (n = 17) was 25.19%. In maxillary sinus carcinomas (n = 3), MT positive index was 4.56% and showed lowers levels as compacted to other SCC sites. Among histological grading in oral and pharyngeal SCCs, MT index of well differentiated SCC (n = 9) was 17.04%, of moderately differentiated SCC (n = 13) 21.92% and poorly differentiated SCC (n = 6) was 31.06%. There is no significant correlation of positive index of metallothionein between treated and untreated samples taken in oral and pharyngeal SCCs.

Fibrin deposition in squamous cell carcinomas of the larynx and hypopharynx.

Extravascular fibrin deposition is frequently observed within and around neoplastic tissue and has been implicated in various aspects of tumor growth. The distribution of fibrin deposits was investigated in squamous cell carcinomas representing different stages of tumor progression of the larynx (n = 25) and hypopharynx (n = 9) by immunofluorescent techniques. Double and treble labelings were used to detect fibrinogen and fibrin in combination with marker antigens for tumor cells (cytokeratin), endothelial cells (von Willebrand factor), macrophages (recognized by KiM7), as well as factor XIII subunit A (FXIIIA) and tenascin (an embryonic extracellular matrix protein newly expressed during tumorigenesis). All tissue samples showed specific staining for fibrinogen/fibrin. Fibrin deposition was localized almost exclusively in the connective tissue compartment of tumors with characteristic accumulation at the interface of connective tissue and the tumorous parenchyma. In certain tumor samples showing highly invasive characteristics, fibrin deposits were observed in close association with tumor blood vessels in the tumor cell nodules. The overlapping reactions with polyclonal antibody to fibrinogen/fibrin and monoclonal antibody to fibrin indicate the activation of the coagulation cascade resulting in in situ thrombin activation and fibrin formation. Fibrin was crosslinked and stabilized by FXIIIA as revealed by urea insolubility test. Accumulation of phagocytozing macrophages detected by Ki M7 monoclonal antibody could be seen in areas of fibrin deposition. The blood coagulation factor XIIIA was detected in and around the cells labeled with Ki M7 antibody. Tenascin and fibrin deposits were found in the same localization in the tumor stroma and in association with tumor blood vessels within the tumor cell nodules. Neither fibrin nor tenascin were detected in the histologically normal tissue adjacent to tumors. The close association between fibrin deposits and macrophage accumulation strongly suggests the active participation of tumor-associated macrophages in the formation of stabilized intratumoral fibrin that facilitates tumor matrix generation and tumor angiogenesis.