FR901469, a novel antifungal antibiotic from an unidentified fungus No.11243. I. Taxonomy, fermentation, isolation, physico-chemical properties and biological properties.

FR901469 is a novel antifungal antibiotic produced by an unidentified fungus No.11243. This compound was isolated from the culture broth by solvent extraction, HP-20 and YMC ODS gel column chromatography, and lyophilization. FR901469 is a white powder which melts at 182 approximately 187 degrees C and possesses the molecular formula C71H116N14O23. This compound has good water solubility. FR901469 inhibited the activity of 1,3-beta-glucan synthase from Candida albicans with an IC50 value of 0.05 microg/ml, and displayed greater inhibitory activity than other 1,3-beta-glucan synthase inhibitors such as, WF11899A, echinocandin B, aculeacin A, and papulacandin B.

FR901469, a novel antifungal antibiotic from an unidentified fungus No.11243. II. In vitro and in vivo activities.

FR901469 is a water-soluble macrocyclic lipopeptidolactone (C71H116N14O23) that has inhibitory activity against 1,3-beta-glucan synthase and exhibits in vitro and in vivo antifungal activity against both Candida albicans and Aspergillus fumigatus. The MICs of FR901469 against Candida albicans FP633 and Aspergillus fumigatus FP1305 in a micro-broth dilution test were 0.63 and 0.16 microg/ml, respectively. FR901469 showed excellent efficacy by subcutaneous injection against both Candida albicans and Aspergillus fumigatus in a murine systemic infection mode, with ED50s of 0.32 and 0.2 mg/kg, respectively. This compound also showed potent anti-Pneumocystis activity in the nude mice model with experimental Pneumocystis pneumonia. The hemolytic activity of FR901469 towards mouse red blood cells, is about 30-fold weaker than that of amphotericin B.

Presence of alpha-fetoprotein mRNA in blood correlates with outcome in patients with hepatocellular carcinoma.

BACKGROUND/AIMS: Since hematogenous spread of tumor cells may adversely affect the prognosis of patients with hepatocellular carcinoma, we prospectively analyzed whether the presence of alpha-fetoprotein (AFP) messenger RNA (mRNA) in blood, used as a marker of circulating hepatocellular carcinoma cells, correlates with outcome. METHODS: Eighty-eight patients were enrolled between December 1993 and August 1995, and 81 were followed until the end of 1997. All patients were treated with percutaneous ethanol injection therapy and/or transarterial embolization during follow-up. The status of AFP mRNA in blood was serially determined. Cumulative metastasis-free survival and overall survival were analyzed in relation to AFP mRNA and other clinical and laboratory variables. RESULTS: Among 81 patients followed, 54 were positive for AFP mRNA at entry and 27 were negative. Extrahepatic metastasis developed more frequently among the AFP mRNA-positive patients (13 of 54) than among the AFP mRNA-negative patients (2 of 27) (p=0.0296). After treatment, AFP mRNA became negative in 24 of 54 patients (44%). Cumulative metastasis-free survival and overall survival were significantly better in the 24 patients whose AFP mRNA became negative after treatment than in the 30 patients with persistently positive AFP mRNA (p= 0.0001 and p<0.0001, respectively). CONCLUSIONS: The presence or absence of AFP mRNA in blood is a predictor of outcome in patients with hepatocellular carcinoma.

Small hyperechoic nodules in chronic liver diseases include hepatocellular carcinomas with low cyclin D1 and Ki-67 expression.

In spite of the importance of periodic screening for hepatocellular carcinoma (HCC) by ultrasonography (US) in patients with underlying liver disease, the clinicopathological characteristics of hyperechoic nodules have not been clearly evaluated. The aim of this study was to characterize the pathological and proliferating features of small hyperechoic nodules. Tissue specimens of 55 hyperechoic and 107 hypoechoic nodules less than 20 mm in diameter in patients with chronic liver disease were obtained by echo-guided needle biopsy and examined histopathologically. Of these, 42 (76%) hyperechoic and 56 (52%) hypoechoic nodules were diagnosed as HCC, and 82% of hyperechoic HCCs contained fatty change and/or clear cell change. In addition, immunohistochemical staining using cyclin D1, p53, and Ki-67 was examined. A high-level expression of cyclin D1 was found in only 5% of hyperechoic HCCs, in contrast to 38% of hypoechoic HCCs (P <.02). The labeling index of Ki-67 in hyperechoic HCCs was lower than in hypoechoic HCCs (4.2% vs. 8.9%; P <.003). However, there was no difference on p53 staining between them. Retrospective follow-up study revealed that hyperechoic nodules showed slow growth (doubling time, median: 1,403 days) initially, and came to show rapid growth (doubling time, median: 56 days). From these results, small hyperechoic nodules in chronic liver diseases are worth notice as candidates for well-differentiated HCC with low cyclin D1 and Ki-67 expression.

Endoscopic variceal ligation is a sufficient procedure for the treatment of oesophageal varices in patients with hepatitis C liver cirrhosis: comparison with injection sclerotherapy.

AIMS: Endoscopic variceal ligation (EVL) is a recently developed alternative to endoscopic injection sclerotherapy (EIS) for the treatment of oesophageal varices. Endoscopic variceal ligation and EIS were compared in an attempt to clarify the efficacy and safety of EVL for patients with cirrhosis due to hepatitis C. METHODS: Endoscopic variceal ligation was performed in 60 patients and EIS in 30. Varices were eradicated in all patients by EVL and 87% (26 out of 30) by EIS. RESULTS: There was no significant difference between EVL and EIS in relation to the incidence of bleeding and the 5 year survival rate after treatment. There were no severe complications except mild substernal pain after EVL, while pulmonary embolism occurred in one patient receiving EIS. CONCLUSIONS: Endoscopic variceal ligation is a safe and effective technique for eradicating oesophageal varices in patients with hepatitis C cirrhosis.

Tissue distribution of placenta-type 6-phosphofructo- 2-kinase/fructose-2,6-bisphosphatase.

Several isozymes of 6-phosphofructo-2-kinase/fructose-2, 6-bisphosphatase have been characterized from mammalian tissues and, based on tissue origin, they are classified as liver, skeletal muscle, heart, testis, and placenta isozymes. In this paper, we examined the tissue distribution of placenta-type isozyme in rat tissues at the levels of transcription and translation. Analysis by Northern blotting showed that placenta, brain, testis, liver, kidney, and skeletal muscle expressed mRNA of placenta-type isozyme. Western blot analysis of fractions from POROS-HQ column chromatography of extracts from various rat tissues showed that proteins of placenta-type isozyme are expressed in placenta, brain, testis, liver, spleen, heart and lung, but not in kidney and skeletal muscle. An immunohistochemical study showed that, in liver, placenta-type isozyme is localized in Kupffer cells. These results indicate that isozymes of this particular enzyme may occur in particular cell types within each tissue.

Power Doppler sonography for hepatocellular carcinoma: factors affecting the power Doppler signals of the tumors.

AIMS/BACKGROUND: A recent advancement in Doppler ultrasonography (US) is power Doppler for detecting low-velocity blood flow at the microvascular level with angle independence. The present study was performed to characterize the factors contributing to the power Doppler signals of hepatocellular carcinoma (HCC). METHOD: Correlation of Doppler signals of HCC in 114 patients with 178 HCC nodules was analyzed in relation to the findings of CT and angiography, tumor characteristics (size, echo pattern, and histological differentiation of tumor), viral markers and severity of liver disease. RESULTS: The sensitivity of power Doppler US was superior to that of CT and angiography (each p<0.05; McNemar's test). The detection rate of power Doppler signal was significantly higher in tumors with diameter > or =2 cm (vs <2 cm in diameter), and with low/mixed echo pattern (vs high echo appearance), and with moderately/poorly differentiated HCC (vs well-differentiated HCC). Univariate analysis revealed that echo pattern, tumor size and histological differentiation of HCC in addition to CT and angiographic findings were significant. Multivariate analysis showed that tumor size and differentiation were significant. CONCLUSION: These results indicate that tumor characteristics play an important role in power Doppler signals and that these could be assessed by the presence or absence of power Doppler signals.

Percutaneous hepatic infarction therapy for hepatocellular carcinoma.

OBJECTIVE: We percutaneously injected ethanol into small vessels afferent to tumor nodules to induce hepatic infarction in areas of tumor caused by hepatocellular carcinoma. CONCLUSION: Percutaneous hepatic infarction therapy holds promise as a new method of treating large hepatocellular carcinoma.

Does dual infection by hepatitis B and C viruses play an important role in the pathogenesis of hepatocellular carcinoma in Japan?

BACKGROUND: There are contradictory data concerning the synergistic effect of hepatitis B virus (HBV) and hepatitis C virus (HCV) infection on the progression from chronic hepatitis to hepatocellular carcinoma (HCC). METHODS: To clarify the role of coinfection with HBV and HCV in the progression and pathogenesis of HCC, viral and clinicopathologic features were studied in 368 consecutive HCC patients at the University of Tokyo from 1991-1995. RESULTS: Approximately 83% of patients (305 patients) were seropositive for the HCV antibody ("C-viral") and approximately 10% (37 patients) were positive for the hepatitis B surface antigen ("B-viral"). Positivity for both (dual infection) was found in only 2% of patients, and negativity for both in 5%. The incidence of dual infection in HCC patients was Similar to that in 549 patients with chronic hepatitis (1%) and 119 patients with cirrhosis (1%). Of the six HCC patients with dual infection, five patients were positive for the HBV early antigen and HBV DNA was less than measurable, whereas HCV RNA was detected and ranged from 10(3)-10(6) copies/50 microL of serum by competitive reverse transcriptase-polymerase chain reaction, and the clinical features resembled those of "C-viral" HCC. The remaining patient was early antigen positive and had HBV DNA by slot blot analysis, but the serum HCV RNA level was less than measurable. These data indicate that mutually exclusive viral replication occurred in patients with persistent coinfection. To further clarify further the possible involvement of HBV infection in "C-viral" HCC, HBV core antibody (HBcAb) was tested in 192 patients and was found to be positive in 111 and negative in 81. The serum HCV RNA level and clinicopathologic features (such as age and the severity of liver disease) were similar among the "C-viral" HCC patients irrespective of the presence or absence of HBcAb. CONCLUSIONS: Based on these results, coinfection was found to be much less prevalent than generally is claimed, and even in a few HCC patients with the coinfection the mutually exclusive viral replication was noted, suggesting that coinfection plays little if any role in the development of HCC.

Direct detection of Mycobacterium tuberculosis using polymerase chain reaction assay among patients with hepatic granuloma.

BACKGROUND: In liver tuberculosis, demonstration of acid bacilli by conventional methods remains futile. Since the definitive diagnosis of liver tuberculosis is based on the histologic evidence of granulomatous process with caseation necrosis, seen in only a third of cases, the diagnosis is made retrospectively by response to empirical anti-tuberculous drug therapy. AIMS: Our objective is to establish a polymerase chain reaction assay for detection of Mycobacterium tuberculosis affecting the liver using the paraffin-embedded liver biopsy specimens obtained from patients with hepatic granulomas. METHODS: As positive control, patients having either "definitive" (n=8) or "presumptive" (n=9) tuberculosis on the basis of clinical, microbiological, histologic data and their positive response to empirical treatment of anti-tuberculous drugs were used. Patients with hepatic granulomas secondary to schistosomiasis (n=6), sarcoidosis (n=2) and other liver diseases (n=10) were used as negative control. RESULTS: Of those patients who were diagnosed as having "definitive" and "presumptive" liver tuberculosis, positivity by one-step polymerase chain reaction was 100% and 44%, respectively. Using the nested polymerase chain reaction, positivity increased to 78% with "presumptive" liver tuberculosis. In contrast, the polymerase chain reaction assays were negative among all patients with hepatic granuloma due to non-tuberculous-in-origin and other liver diseases. CONCLUSIONS: The overall positivity of this polymerase chain reaction assay (88%) compares favorably with that of other conventional methods (12%). Thus, this polymerase chain reaction assay may be a reliable diagnostic tool for liver tuberculosis in a patient population in which the prevalence of diseases associated with hepatic granuloma is common.

In vivo selective gene expression and therapy mediated by adenoviral vectors for human carcinoembryonic antigen-producing gastric carcinoma.

Previously, we reported that adenoviral vectors carrying the carcinoembryonic antigen (CEA) promoter sequences to direct the Echerichia coli beta-galactosidase gene (AdCEA-lacZ) or cytosine deaminase (CD) gene (AdCEA-CD) confer selective gene expression on a CEA-positive gastric cancer cell line (MKN45) in vitro. Here, adenovirus-mediated tumor-specific gene therapy for CEA-positive gastric carcinoma in vivo was investigated. Using an animal model with i.p. disseminated MKN45 tumors, adenovirus-mediated tumor-specific transgene expression and therapeutic efficacy were analyzed. After an i.p. injection of AdCEA-lacZ, beta-galactosidase activity was confined to tumor xenografts. Moreover, CD mRNA was expressed exclusively in MKN45 tumor xenografts after infection with AdCEA-CD, despite the fact that an adenovirus-mediated transfer of CD DNA was detected in all tissues tested. In contrast, CD mRNA was detected not only in tumor xenografts but also in other organs of mice infected with AdCA-CD, in which CD gene expression is governed by an ubiquitous promoter. Suppression of tumor growth and prolongation of survival were noted in tumor-bearing mice treated with AdCEA-CD and 5-fluorocytosine (5FC) without observable adverse effects. In contrast, significant hepatic toxicity was noted in animals treated with AdCA-CD. These results reveal that the CEA promoter restricts CD gene expression to CEA-positive tumor cells in the adenoviral context in vivo, along with the beneficial therapeutic effects of 5FC treatment, suggesting the i.p. AdCEA-CD/5FC system may provide a novel approach to treatment of i.p. disseminated gastric cancer.

In vivo gene therapy for alpha-fetoprotein-producing hepatocellular carcinoma by adenovirus-mediated transfer of cytosine deaminase gene.

The alpha-fetoprotein (AFP) gene is normally expressed in fetal liver and is transcriptionally silent in adult liver but overexpressed in human hepatocellular carcinoma (HCC). Here, we demonstrate that replication defective recombinant adenoviral vectors, containing the human AFP promoter/enhancer, can be used to express the Escherichia coli cytosine deaminase (CD) gene (AdAFPCD) and the beta-galactosidase gene (AdAF-PlacZ) in AFP-producing HCC cell lines. Expression of the CD gene by adenovirus from the AFP promoter/enhancer (AdAFPCD) induced cells sensitive to 5-fluorocytosine (5FC) in the AFP-producing cells but not in the AFP-nonproducing cells. Transduction by an adenoviral vector harboring an ubiquitous strong promoter and CD gene showed enzymatic activity and 5FC killing in all cell lines. When AdAFPlacZ was injected into the s.c. established hepatoma in vivo, expression of the beta-galactosidase gene was confined to AFP-producing HCC xenografts. Moreover, HCC xenografts regressed by transduction with AdAFPCD and subsequently with 5FC treatment in vivo. These findings suggest that utilization of the AFP promoter/enhancer in an adenoviral vector can confer selective expression of a heterologous suicide gene in hepatocellular carcinoma cells in vitro and in vivo.

Treatment of head and neck cancers with BRMs--prolongation of survival.

It has been reported that immunologic function is deteriorated in head and neck cancer patients by primary therapies such as surgery, irradiation and chemotherapy or tumor itself. As previously described by us, immunologic dysfunction in such patients may be recovered by treatment with BRMs. In the present study, we investigated the effects of BRMs on survival of patients who had primarily been treated in our clinic. Fifty-one patients (23 patients; Stage I or Stage II, 28 patients; Stage III or Stage IV) were treated with BRMs (BRM group), and 49 patients (22 patients; Stage I or Stage II, 27 patients; Stage III or Stage IV) were employed as controls (Control group). The results obtained were as follows: (1) In patients of all Stages, the survival period was significantly (p < 0.05) longer in BRM group than in Control group; (2) The survival periods of patients of Stage I or Stage II were not different between the groups; and (3) The survival period of BRM group was significantly (p < 0.05) longer than that of Control group in patients of Stage III or Stage IV. There were observed more patients in BRM group who survived for a prolonged period. These results suggest that BRMs may be useful for recovering immunologic function in head and neck cancer patients particularly of Stage III or Stage IV who usually receive multimodality therapy.

Quantitation of alpha-fetoprotein and albumin messenger RNA in human hepatocellular carcinoma.

To analyze gene expression of alpha-fetoprotein (AFP) and albumin in hepatocellular carcinoma (HCC), messenger RNAs (mRNAs) of these proteins in six human hepatoma cell lines and in 30 cases of HCC were quantitatively analyzed by competitive reverse transcription (RT) followed by polymerase chain reaction (PCR). The transcriptional levels of both AFP and albumin genes in HepG2 and Huh 7 cell lines were 10(10) copies/microgram RNA, in contrast to approximately 10(5) copies/microgram RNA in HLE and HLF cell lines. AFP and albumin mRNA levels in three normal livers were 10(5) and 10(10) transcripts/microgram RNA, respectively. In 30 cases with HCC AFP mRNA level in neoplasm was 10 to 10(5)-fold enhanced as compared with that of nonneoplastic portion, and correlated with serum AFP level and tumor size (P < .01). In contrast, albumin mRNA level was not reduced in the neoplasms presenting enhanced AFP mRNA levels, indicating that AFP and albumin gene expression in situ is not necessarily mutually exclusive. Prospective analysis revealed that an increased serum AFP was shown at the time of recurrence among patients with enhanced AFP mRNA levels in neoplasm only, indicating that AFP mRNA levels in neoplasm could be a clinically predictable tool.

[Percutaneous ethanol injection therapy for small hepatocellular carcinoma].

Hepatocellular carcinoma is different from other solid tumors. Because of concomitant cirrhosis or multiple lesions, most hepatocellular carcinoma is unresectable. Still worse, hepatocellular carcinoma frequently recurs after surgical resection; the 5-year cumulative recurrence rate is 70-90% even after curative hepatectomy. The situation is similar in small hepatocellular carcinoma 2 cm or less in diameter. Thus, non-surgical treatment plays an important role. At present, we think that percutaneous ethanol injection therapy (PEIT) is best for the treatment of hepatocellular carcinoma because of its local curativity, minimal adverse effect on liver function, and the easy feasibility of repeated treatment for recurrence. We have recently treated about 85% of hepatocellular carcinoma cases by PEIT and have achieved satisfactory long-term results. Here we describe our results in PEIT for small hepatocellular carcinoma. By the end of December 1995, we performed PEIT on 410 patients with hepatocellular carcinoma. Among them, 140 patients were diagnosed as having small hepatocellular carcinoma 2 cm or less in diameter. The 1-, 3-, 5-, 7-, and 10-year survival rates of the 140 patients were 93%, 73%, 55%, 51%, and 32%, respectively. Furthermore, in 83 patients who had a single, small hepatocellular carcinoma 2 cm or less in diameter, the 1-, 3-, 5-, 7-, and 10-year survival rates were 92%, 82%, 72%, 66%, and 66%, respectively. Thus PEIT achieved satisfactory long-term survival rates in the treatment of small hepatocellular carcinoma.

Analysis of K-ras gene mutation in hyperplastic duct cells of the pancreas without pancreatic disease.

BACKGROUND & AIMS: We and others have previously shown that the mutation of K-ras codon 12 was found in the majority of pancreatic adenocarcinomas. The mutation has also been identified in the pancreatic duct with mucous cell hyperplasia in association with chronic pancreatitis. Ductal hyperplasia is also frequently found in the pancreas free from pancreatic carcinoma or chronic pancreatitis. The aim of this study was to assess the incidence and types of mutations in hyperplastic foci in these cases. METHODS: The nucleotide sequence of the K-ras gene at codon 12 of the DNA extracted from microdissected hyperplastic epithelium of the pancreatic duct obtained at autopsy in patients without pancreatic adenocarcinoma or chronic pancreatitis was analyzed. RESULTS: Of 38 patients with 79 hyperplastic foci, 12 patients (with 19 hyperplastic foci) had mutations. None of the 16 normal ducts in 12 specimens had this mutation. The nucleotide sequence of the codon in 53% of ductal hyperplastic foci was TGT or AGT, both of which were not found in 30 cases of adenocarcinoma. CONCLUSIONS: These results suggest that the ras gene mutation occurs frequently in multifocal hyperplastic foci of pancreatic duct and that the mutations may not have direct relevance to the carcinogenesis of pancreatic cancer.

Photodynamic therapy for head and neck cancer.

Photodynamic therapy (PDT) is a recently developed treatment involving the use of a photosensitizer and low power light, usually from a laser, to selectively destroy tumor cells. At present, we perform PDT for head and neck cancer using argon or excimer dye lasers with hematoporphyrin derivative as a photosensitizer. This study attempted to assess the utility and safety of PDT and to investigate the long-term outcome. All 24 patients had squamous cell carcinoma: 15 with laryngeal, 5 with lingual or oral, and 4 with pharyngeal cancer and were treated by PDT. Data were obtained from records from February 1988 through April 1995. After PDT, 12 of 15 laryngeal cancer patients were classified as having a complete remission (CR), as were 2 of the 5 lingual or oral and one of the 4 pharyngeal cancer patients. The patients were followed for 8 to 153 months. The longest duration of CR in patients treated by PDT alone was 148 months. Photosensitivity was experienced by all patients, but required no treatment. Liver, kidneys, and bone marrow showed no abnormal values. There were no clinically relevant adverse reactions, and patients with severe complications due to other types of treatment and elderly patients were also treated safely with this therapy.

Characteristic difference of hepatocellular carcinoma between hepatitis B- and C- viral infection in Japan.

Characteristics of 205 consecutive patients with hepatocellular carcinoma (HCC) admitted during 1990 to 1993 have been analyzed from the standpoint of hepatitis viral infection in Japan. Among 205 HCC patients, 71% of the patients showed positivity for hepatic C virus (HCV) antibody alone, 13% showed positivity both for HCV and HBV (HCV/HBV) antibody, 11% demonstrated HBsAg alone, and negativity of both HCV and HBV antibody in 4% only. Positivity to both HCV antibody and HBsAg was demonstrated in 1% only. Mean detection age of HCVAb-positive HCC as well as both HCV/HBV antibody-positive HCC was 62 +/- 7 years, in contrast to 52 +/- 13 years in HCC with HBsAg (P < .05). Male-to-female ratio among HCVAb-positive HCC was 3.3:1, in contrast to 5.5:1 among the HCV/HBVAb-positive HCC and 7:1 among HBsAg-positive HCC, but there was no significant difference in the gender distribution between these groups. More than 60% of HCVAb-positive HCC and HCV/HBVAb-positive HCC were classified into the stage of Child B and C, whereas 65% of HBsAg-positive HCC was at the stage of Child A. The severity of liver disease was confirmed by liver histology, indicating that more than 70% of the HCVAb-positive HCC and the HCV/HBVAb-positive HCC showed cirrhosis, in contrast to 50% among the HBsAg-positive HCC. Three-year survival rate of HCV Ab-positive HCC and HBV/HCVAb-positive HCC was 68% and 56%, respectively, in contrast to 47% in HBsAg-positive HCC.(ABSTRACT TRUNCATED AT 250 WORDS)

Prevention of breast tumour development in vivo by downregulation of the p185neu receptor.

Certain strains of transgenic mice that express the rat neu oncogene (neuT) in mammary epithelial cells develop breast tumours at an average of 44 weeks of age. In this study, intraperitoneal injection of a monoclonal anti-receptor antibody specific for the rat neuT oncogene product dramatically affected tumour development in these transgenic mice in a dose-dependent manner. A significant proportion (50%) of mice, when injected with anti-receptor antibodies, did not develop tumours even after 90 weeks of age. The phosphotyrosine levels of the membrane fraction of breast tissues in the anti-receptor antibody-treated mice were almost completely abolished when a higher dose of antibodies was used. This study demonstrates, for the first time, that immunologic manipulation of an oncogene product can effectively prevent the development of tumours in a rodent transgenic model.

[Clinical study of photodynamic therapy for laryngeal cancer].

Photodynamic therapy (PDT) is an innovative treatment involving the use of a photosensitizer and low powered laser to selectively destroy tumor cells. In the head and neck, its application to laryngeal papilloma, metastatic tumor and oral cancer have been reported but our report on PDT for laryngeal cancer is the only clinical report in Japan. At present, we treat laryngeal cancer by PDT using argon and excimer dye lasers such as the HpD. In the present study, we assessed the utility and safety of PDT and investigated long-term prognosis after this therapy. The subjects were 12 patients with laryngeal cancer who underwent PDT between February 1988 and October 1993. Among them, ten with cancer of the vocal cords underwent PDT as the primary treatment and two underwent PDT because of recurrence after radiotherapy. Under local anesthesia, PDT was performed using a video endoscope (Pentax EB2000). The optimal dose from an argon dye laser was set at 200-500 mW/cm2 of continuous waves for 20 minutes and that from the excimer dye laser was set at 200 J/cm2 of pulse waves (3-4 mJ/pulse, 30-40 Hz). The argon dye laser used was the Fujinon PDT developed by Fuji Photo Optical Co., Ltd. The excimer dye laser used was a product of Hamamatsu Photonics Co., Ltd. 1) Effect of PDT The effect of PDT as a primary treatment for ten patients was classified as CR in eight and PR in two cases, the CR rate being 80.0%. When evaluated only for T1 patients, the results were classified as CR in eight and PR in one. The patient whose response was classified as PR had refused repeated PDT. CR was maintained for five and 13 months in the two patients who underwent PDT as a secondary treatment after radiotherapy. CR was obtained in 83.3% of all patients studied. 2) Duration of the effect of PDT and long-term prognosis The patients were followed up for 14 to 71 months. The longest duration of CR achieved by PDT monotherapy was 65 months. Among the patients who underwent PDT as a primary treatment, one developed local recurrence and underwent radiotherapy. However, the prognosis was uneventful in all other patients. CR after PDT monotherapy was maintained for 42 months in one T3 patient. Two patients with a history of previous treatment thereafter relapsed and underwent total laryngectomy. The larynx could be conserved in 83.3% of all patients. However, it could be conserved in 100% of patients who underwent PDT as a primary treatment.(ABSTRACT TRUNCATED AT 400 WORDS)