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The 12 th Oncology Forum discussed the progress and future strategy of cancer prevention in Japan. The National Cancer Center has established a research center for screening focusing on the most common six cancer, stomach, lung, liver, colon, breast and uterus cancer. The program so far had a cumulative detection rate of 3.3%, which is high,and may reflect the selection of subjects. Screening and chemoprevention is also being investigated in prostate cancer, but the issues centre on how to make this widely available. High risk subjects can also be identified for breast cancer. Obesity and family history are especially important. In colorectal cancer studies are evaluating different diets, but general application is not yet possible and the infrastructure to implement any general screening and prevention does not exist. Development of pharmaceutical treatments for prevention is difficult because of the need for very safe treatments, and also because of the length of time needed to carry out studies. Overall, cancer prevention is still in evolution. New approaches are needed, and new infrastructure will be needed at a government level to implement this.

The purpose of cancer screening is to widen the difference between morbidity and mortality of the target cancer. Since 1983 cancer screening has been supported by the Japanese government. Initially it covered gastric and cervical cancer with lung, breast and endometrial cancers supported from 1987 and colorectal cancer in 1992. Since 1998 support for cancer screening has been transferred to local government. It is generally accepted that the uptake of screening services is too low. Estimates for Japan suggest that at best 30% of the eligible population accept the services. In other parts of the world screening is more widely accepted, for example, 67% for breast cancer and 79% for cervical screening in the USA. Barriers within Japan for increasing screening are complex and include, legal, ethical, financial, technical infrastructure, data related matters and the level of understanding and education of the general public. In 2000 the MHLW conducted an evaluation of cancer screening in terms of usefulness and effectiveness. It concluded that fair or better evidence for reduction in mortality existed for cervical cancer (cytology), breast cancer (mammography with clinical examination for women aged > or = 50 years), colorectal cancer (faecal occult blood test), gastric cancer, lung cancer and liver cancer. As a step towards improving screening services and their uptake by the general public a new Research Centre for Cancer Prevention and Screening was established at the National Cancer Centre in October 2003. This and other initiatives will build on the progress of the past 20 years but it is generally agreed that there is still have a long way to go.

We selected ovarian cancer as being the most representative of the gynecologic malignancies since it has the largest number of tumor markers now in clinical use. First, variety of serum tumor markers were developed and regularly used to detect the existence of ovarian cancer and its stage. These markers of monoclonal antibodies could detect three different classes of cell surface antigen. CA 125, CA 130, CA 602 are antibodies raised against the core protein of the proteoglycan molecule, whereas CA 19-9, CA 50, KMO-1 and CA 72-4, STN, CA 546 are antibodies against a different portion of the glycosaminoglycan chain from the core protein. These markers, when combined with another group of tumor markers for discriminating the variety of pathological types of ovarian cancer, might have the potential to provide a better predictive value. Second, biomarkers for the detection of early-stage ovarian cancer are urgently needed and developed also in gynecologic tumors. These include a ovarian cancer-specific proteomic patterns generated by mass spectroscopy and single nucleotide polymorphism (SNP) digital analysis combined with assessment of allelic imbalance. Third, for monitoring the effect of treatment with cytostatic drugs, various types of biomarkers could be used as surrogate markers for the treatment depending on the mechanism of the effects of the drug used. For treatment with Bryostatin, a strong protein kinase C (PKC) stimulator, PKC activity promises to be an effective marker. For the trials with bevacizumab, anti-VEGF antibody, VEGF and its associated bFGF, CD-31, and thrombospondin-1 (TSP-1), are leading candidates for monitoring markers.

Based on presentations on the basic concepts and scientific rationale of anti-angiogenic approaches to cancer therapy and the possible applications in the area of prostate cancer, gastrointestinal cancer, lung cancer and breast cancer it is easy to conclude that development of anti-angiogenic approaches into clinical therapies is extremely challenging. It is now well established that cancer growth is increased by angiogenic factors and that inhibition of angiogenesis decreases growth and metastatic potential. Anti-angiogenic effect can be obtained through interference with multiple targets. Further development of new strategies involving such novel cancer therapies requires wide reaching development of translational research abilities. However, for moving new therapies into the clinic same rigorous criteria need to be applied as is done for traditional therapies. Angiogenesis appear to be a critical factor for development of prostate, gastric, lung and breast cancers. Development of new anti-angiogenic treatment modalities might become very important in these diseases. A critical requirement for the successful clinical development will be the development of imaging techniques that can help evaluate the effect on blood vessel functionality. Such surrogate markers of anti-angiogenic effect will be essential for optimising molecules and doses.

Based on reviews of the concept of diagnostics and in general and in specific tumour areas it was clear that development of diagnostic procedures involving genomics will allow for much better targeted and tailored treatments in the future. This will result in better efficacy and better tolerability of cancer treatments, but will also allow for progress in prediction, diagnosis and dose selection. Large collaborative projects studying the efficacy and safety of drugs on the genome level is promising to bring important benefits to both patients and the national economy by reducing useless drug therapy. In colorectal cancer there are several genetic defects identified that can act as the target for directed therapy in the future. Expressions of tumour specific antigens open the way for immunological targeted therapies. Developments in the understanding of the genomic basis for resistance to anti-tumour therapy is promising to help targeting patients likely to respond and not develop resistance. A Japanese model is being developed to determine the relative risk of breast cancer of Japanese women. Based on this prevention therapies can be instigated. The last four years have seen the introduction of four novel targeted therapies. If this model should become a standard in the future, much stronger collaboration between academic research and pharmaceutical industry need to develop.

Based on reviews of the Japanese clinical trial situation in lung cancer, gastric cancer, prostate cancer and breast cancer, it was clear that much progress has been made in short time. There are considerable differences between Japan and the West and also differences between clinical areas in Japan. For regulatory purposes bridging studies have become increasingly important. Use of identical protocols are required for effective bridging. Participations in global phase III trials is the best way of achieving registration in Japan. For successful global trials in Japan it is important to include Japanese investigators in the preparation of the protocol and to recognise the challenges facing such a project. Clinical practice in diagnosis and treatment have many differences, thus it is recommended to have clear and detailed information in the protocol. Hard end points like survival are important since they are not biased by cultural differences. There are clear difficulties with HE or QOL outcomes. The emergence of focus on evidence based medicine is also happening in Japan and will help to harmonize documentation across the world. For large adjuvant or prevention cancer global trials are essential. To facilitate global studies further development of infrastructure is necessary in Japan. Use of electronic data capture web based communication etc. will help overcome communication difficulties. Other improvements that will make Japanese participation in global trials easier and better include establishment of clinical trial centre at each hospital, introduction of trial coordinators or study nurses and an improved collaboration with company staff. A critical issue that also need addressing is agreement of centre target recruitment. We need to introduce a new flexible system in Japan if participation in global trial is to be optimised. If we can address these issues Japanese investigators and collaborative groups should be able to initiate and lead global trials in the future.

Evidence Based Medicine (EBM) is a growing concept in Japan as it is elsewhere. Central to improving the use of EBM is generation of data through well conducted controlled clinical studies. There are many problems associated with conduct of clinical studies after launch in Japan, and many initiatives are ongoing to improve the situation. Development of Clinical Research Coordinators (CRO) and central Data Management centers are key to improving the quality of clinical research in Japan. Currently Japan has an undeveloped legal system with regard to post-launch trials and off-label use of registered drugs. There is no reimbursement for off-label and various restrictions imposed on the recipients of the Ministry of Health, Labour and Welfare's (MHLW) funds. Maybe the biggest problem is the high cost of post-marketing studies sponsored by pharmaceutical manufacturers. A high quality system to support post launch clinical studies need a solid financial base. There is a need for a suitable review system for investigator initiated multi-centre studies, as the current IRB system is not sufficient. There are also challenges regarding the differences, perceived or real, in treatment practice and available registrations in Japan and in the West, causing problems in choosing suitable comparators and study designs. At the present time it is not clear whether investigator initiated trials will be acceptable for registration purposes in Japan. The agreed first priority is to build a suitable and strong infrastructure within the academic community to support researchers to investigate important questions with or without pharmaceutical company support. Despite all these issues, several groundbreaking projects are under way throughout Japan, in many different areas and by different collaborative groups, some with government support. In fact, researcher-initiated clinical trials achieved a rapid growth in Japan in the past year.

Despite improvements in median and overall survival from a combination of improved operation techniques and chemotherapy with platinum-compounds and paclitaxel, long-term survival rates for patients with epithelial ovarian carcinoma remain disappointing, and ongoing efforts are aimed at developing more effective primary therapies. In early ovarian carcinoma, conservative management is used to denote surgery that preserves reproductive potential without compromising curability. With some exceptions, such a strategy may be applicable for women younger than 40, who wish to bear children. A major dilemma facing gynecologic oncologists is to determine whether the accurate staging laparotomy is needed for apparent low-risk stage I ovarian carcinoma and how many cycles of chemotherapy will be needed for high-risk stage I ovarian carcinoma. In advanced ovarian carcinoma, main objectives of salvage therapy include: a improvement in quality of life and symptoms; b. tumor load reduction and survival advantage; c. evaluation of potentially active new drugs to be included in first-line treatment. We need to evaluate the potential benefit on survival of systematic pelvic and para-aortic lymphadenectomy during primary or secondary cytoreductive surgery in patients with advanced ovarian carcinoma. Paclitaxel/cisplatin is considered to be the international standard treatment based on the data of GOG 111 trial showing that paclitaxel/cisplatin has provided a survival benefit better than that of cyclophosphamide/cisplatin. This choice of standard therapy might, however, be questioned based on the results of the largest randomised study, ICON3. There were no statistically significant differences in progression-free or overall survival among paclitaxel/carboplatin and carboplatin only or a platinum combination (cyclophosphamide/doxorubicin/cisplatin). The best selection for adjuvant chemotherapy is still controversial and a large number of studies are now ongoing.

Based on short reviews of lung, gastric, colorectal, prostate, breast and ovarian cancer, there remain significant differences between Japan and the West in the therapeutic regimen for most cancers. Some of the differences are due to differences in stage of disease at diagnosis or historical factors affecting availability of products. In both Japan and the West, there are initiatives to prepare treatment guidelines based on published data. For Japan this initiative is limited by the lack of Japanese clinical trial data or even safety data. When guidelines are prepared from international data, many of the products have limited indications in Japan and therefore not reimbursed. Availability of the most appropriate therapies to Japanese patients will depend on a facilitation of clinical trials in both primary and additional indications. However, the experience in other countries is that, even where data and registration approval are available, guidelines are hard to agree and are not uniformly accepted by prescribers. The ICH E5 guideline on the use of bridging studies to interpolate Western data to Japanese regulatory dossiers provides an opportunity to accelerate availability of new medicines to Japanese prescribers and patients. The use of bridging studies has so far been limited for anti-cancer therapies. Where relevant pharmacodynamic endpoints can be measured, (e.g. aromatase inhibition) there can increase confidence in bridging. The newer types of agent which act to stabilise disease rather than tumour shrinkage present a special problem. In some cases surrogate markers can be valuable but in each case they need to be validated. As globalization continues, an alternative approach is to include a significant cohort of Japanese patients in Japanese patients but this depends on sufficient similarity in the patient population and background therapy. The most significant limitation to either large outcome studies in Japan or for Japanese centers to join international trials has been the environment for conduct of clinical trials. There have been some recent improvements and further progress is expected so that Japanese doctors can play a full role in the evaluation of new therapies.

The management of advanced cancer presents the greatest challenge to physicians involved in oncology. There will usually be a large burden of disease; cure is unlikely; and the needs of the patient in terms of pain control and palliation will also be important over and above the direct treatment of the disease. Different issues will arise depending on the site and pathological type of the cancer. Increasingly over the past few years, treatment protocols and guidelines have been developed for different cancers, but these can only be rough guides rather than definite treatment recommendations. Additionally in most cancers advanced disease offers the opportunity for evaluation of new treatments in Phase II studies and other trials. With the new generation of molecular targeted therapies, such as EGFR inhibitors, striking results are being seen in advanced disease that compare favourably with what has been seen previously. Other agents such as those which attack the tumour vasculature may also have promise in this setting. Palliation is also an important aspect of the management of advanced disease, and pain control in particular is an important component of patient management. In summary, the treatment of advanced disease provides a test bed for new agents, but this need to develop better cancer therapies must be balanced against patient needs for a pain-free and comfortable end to life.

Platinum cytotoxics play an important role globally in the management of solid tumours. Cisplatin sets the standard for efficacy in both regions with careful administration to reduce nephrotoxicity. Carboplatin is associated with neurotoxicity, but has become the leading product in the US due largely to the easier to manage toxicity profile. Both agents have been widely used in both registered and non registered indications and are frequently combined with other cytotoxics. In Japan, cisplatin has been used successfully at low doses in combination with 5-FU based regimens and appears to achieve a synergistic effect, but controlled data are not yet available. More recently oxaliplatin (Europe) and nedaplatin (in Japan) have been introduced, but their clinical roles in therapy have yet to be established. One of the limiting features of the first generation of platinum compounds is that a significant proportion of tumours develop cross resistance to platins due to either changes in uptake or excretion, intracellular detoxification or accelerated DNA repair. The forum discussed the possibility for the development of better new platinum compounds, A new platin agent which had lower toxicity and higher efficacy across a wide range of cancers without the development of resistance would be a significant step forward. If the tolerability profile was suitable, an oral formulation may improve the quality of life for patients but this must not be at the expense of efficacy. Even after the introduction of new target based drugs, platinum cytotoxics are likely to be used to reduce the tumour mass and in some cases can be expected to potentiate the effects of the new agents. In preclinical studies, ZD0473 has been shown to by-pass some major mechanisms of resistance and has the potential to achieve these objectives and is now being evaluated in clinical studies in both Japan and the West.

A survey of cancer treatment in a sample of hospitals > 100 beds conducted in 1998 compared with experience in the US showed that good progress has been achieved in Japan in the screening and early treatment of gastric cancer, and that the prognosis for breast cancer is better than in the West. Although in the past, the cytotoxic therapies available to physicians in Japan vs the West have been different, recent acceleration of regulatory review will result in a convergence of treatment paradigms and some improvement in acute response in many tumour types. However, world wide there is a need for new improved therapies in all cancers evaluated. Particular needs are in the management of NSCLC, advanced disease and cancers which form micrometastases. The eventual hope is that cancer can be turned from a lethal disease into a chronic disease where patients maintain a good QOL. Apart from anti hormonal therapies, the usual approach has been to kill the cancerous cells. However, the new approaches to intervening in the growth and migration of cancerous cells or the host tissue response by molecular targeting offer the promise of achieving a step change in therapy. Although EGF tyrosine Kinase inhibitors such as ZD 1839 have been shown to cause a conventional tumour response in NSCLC, many of these new approaches are unlikely to show a short term response even if they have the capacity to affect tumour development and increase disease free survival. Some compounds will require combination therapy with a conventional cytotoxic or radiotherapy to show their full benefit. For conventional cytotoxics, the usual approach to development has been to select the maximum tolerated dose and then evaluate the efficacy in advanced disease. However, for the new approaches which will not have such severe dose limiting toxicities, it will be necessary to select a surrogate marker of the intended biological effect to select the optimal biological dose (OBD) and dose regimen in phase I/II studies for further evaluation in phase II or III studies which are designed to show the expected patient benefit. The tumour target, the stage of the disease and the possible need for concomitant therapy will also have to be considered according to the mechanism of action of the product.

As illustrated by prostate cancer screening provides an opportunity for early intervention and treatment. However the screening test needs to detect patients with cancer with a low rate of false positives and at a stage which can be treated. Recently the concept of treating patients at high risk of developing breast cancer or suffering a recurrence has been highlighted by the western studies with Nolvadex (tamoxifen). Thus roundtable discussion (held in Tokyo) discussed the different strategies in Japan compared to US & Europe for screening & early intervention/prevention of cancer for breast, prostate, bladder, liver, lung, gynaecological & GI cancers. The range of strategies for cancer screening, how it is funded, whether it is appropriately targeted and whether there is any evidence for a beneficial effect on morbidity or mortality & future prospects for improved sensitivity through new methodology or markers were discussed. Although the relative rates of cancer vary between Japan & the West, the same factors seem to influence cancer development & the data on intervention were seen to be valid. The changing patterns of cancer in Japan suggest a clear opportunity for reducing, the incidence of cancer through lifestyle modification. For some cancers, e.g. cervical & bladder where there is a clear link between abnormal cytology & development cancer true prevention is already practiced. In other cases, preventive treatment is limited by the efficacy of available therapies. As far as drug treatment is concerned, funding of healthcare in Japan does not recognise the concept of prevention although there is, in practice, no barrier to the use of interventions where there is a clear link between biochemical/histological markers & development of cancer.

Methotrexate produced the first remission in leukemia and the first cure of a solid tumor, choriocarcinoma. Methotrexate tightly binds to dihydrofolate reductase (DHFR), blocking the reduction of dihydrofolate to tetrahydrofolic acid, the active form of folic acid. Methotrexate also directly inhibits the folate-dependent enzymes of de novo purine and thymidylate synthesis. Resistance to methotrexate may develop as a result of elevated DHFR activity or defective transport of methotrexate into malignant cells. Increased DHFR enzyme levels may also result from amplification of the DHFR gene, which is now clinically significant in selected patients. Methotrexate is an active drug in the first-line treatment of gestational trophoblastic disease (GTD) and in metastatic squamous cell carcinoma of the cervix. Since the introduction of methotrexate chemotherapy for malignant GTD, most hospitals have reported almost 100% cure rates for patients with nonmetastatic disease using single-agent regimens. Patients with low-risk metastatic disease have been treated with methotrexate and folinic acid and over 50% complete remission rates have been reported. Patients with metastatic GTD who had one or more high-risk factors benefited from initial multiagent chemotherapy, rather than waiting for acquisition of drug-resistance to single-agent therapy to start multiagent treatment. Using multiagent combination chemotherapy such as MAC (methotrexate, actinomycin D, cyclophosphamide) or EMA-CO (etoposide, methotrexate, actinomycin D and cyclophosphamide, vincristine), most investigators have reported remission in approximately 60 to 80% of patients with high-risk metastatic GTD. Although the role of chemotherapy in carcinoma of the cervix has been limited for several reasons, trial of combination chemotherapy including methotrexate has been reported. However, it is still impossible to draw definite conclusions as to whether methotrexate combined with another clearly active drug may yield a superior response rate and survival.

A phase II study of Paclitaxel in patients with ovarian cancer by 3-hour intravenous infusion was undertaken by a cooperative study group of 30 institutes. Of 66 cases enrolled, 57 cases were evaluable for efficacy, and 63 cases were evaluable for safety. In spite of the fact that all cases for efficacy evaluation were previously treated with chemotherapy including platinum-based drugs, 2 cases of complete response (CR) and 15 cases of partial response (PR) were observed, with a response rate of 29.8% (The 95% confidence interval of response rate was 18.4-43.4%). Paclitaxel also showed 28.2% (11/39) response rate in patients refractory to treatment by platinum-based drugs. Histologically, the response rates were 28.9% (11/38) in serous adenocarcinoma, 40.0% (2/5) in clear cell adenocarcinoma and 25.0% (1/4) in mucinous adenocarcinoma. As the major laboratory abnormalities, leukopenia, neutropenia and decrease in hemoglobin were observed with incidence rates of 98.4% (62/63), 95.2% (59/62) and 85.7% (54/63), respectively. However, these abnormalities were clinically manageable by either withdrawal of medication, administration of antibiotics, G-CSF or metachysis etc. In addition, thrombocytopenia, elevation in GOT and GPT were seen with moderate incidence. Peripheral neuropathy was a major adverse symptom with an incidence of 79.4% (50/63), followed by alopecia, myalgia, arthralgia and fever. However, the majority of these adverse reactions were less than grade 3. From these findings, we confirmed that 3-hour intravenous infusion of Paclitaxel was a clinically useful chemotherapeutic agent in patients with ovarian cancer.

Surgery remains one of the important factors in the treatment of the ovarian cancer. Ovarian cancer spreads primarily by exfoliating malignant cells from the tumor surface that in turn implant throughout the peritoneal cavity. On the basis of the patterns of this spread, a stage-specific operation for ovarian cancer is currently being established. In early ovarian cancer, the initial operation allows a complete assessment of the spread of the disease. For stage I ovarian cancer, uni- or bi-lateral salpingo-oophorectomy was performed when a patient showed grade I well-differentiated tumor, no extra capsular proliferation, and intact capsule. For patients with advanced disease, the initial cytoreductive operation with the compulsory resection of involved portions of the bowel reduces tumor bulk and produces increased sensitivity to chemotherapy for the remaining tumor. Survival time increases further in proportion to decrements in tumor size below 2 cm in its maximum diameter. Even within the optimal group of patients, in whom the maximum diameter of residual disease was < or = 1 cm, there was a survival difference between patients with microscopic residual disease and those with any macroscopic disease < or = 1 cm. Among with suboptimal group of patients, in whom the maximum diameter of residual disease is > 1 cm, and who receive the following platinum containing chemotherapy, those who have a small diameter of residual disease (< 2 cm) tend to survive longer than those with larger residual disease. Among those with the larger residual disease, the size of the tumor does not affect the prognosis. Optimal or suboptimal tumor resection is associated with a more complete response to chemotherapy. The principles of cellular kinetics provide good theoretical evidence of the benefit of cytoreductive surgery.

Since 1986, attempts have been made to improve the anti-cancer effect of Cisplatin (CDDP) in malignant ovarian tumor patients and their quality of life (QOL), by increasing single and total dose of CDDP and by short-stay cyclic treatment at our institution. In this study, the side effects of CDDP at high and low doses were compared and the effect on the QOL was analysed. Twenty ovarian malignant tumor patients who underwent adjuvant chemotherapy (CDDP 70 mg/m2, Adriamycin (ADR) 20 mg/m2, Cyclophosphamide (CPM) 200 mg/m2 given every 4 weeks for a total of 5 times and every 8-12 weeks thereafter for 5 times) after initial surgery were compared with non randomized control patients who received the old regimen of of our institution (CDDP 35 mg/m2, ADR 20 mg/m2, CRP 200 mg/m2, 5-FU 150 mg/m2 for 5 days given every 4 weeks for a total of 5 times without discharge from hospital). There was no significant difference between the groups in the white blood cell (WBC) count and creatinine clearance (Ccr) throughout the treatment, although a slight drop was observed after the second course in both groups. The QOL was examined by interviewing the patients on their physical and mental condition. Although the total amount of CDDP was increased from 175 mg/m2 to as much as 700 mg/m2, no severe nephrotoxicity or myelosuppression was seen and patients felt better and preserved a good QOL during a short hospital stay. These results clearly indicate the efficacy of our new regimen.

This study was provided biochemical findings on ascitic fluid following the treatment of patients with ovarian tumors. The results were as follows: LDH and LDH isozyme. The ascitic fluid from patients with germ cell tumors showed an LDH1 value of 38.8% with an H/M ratio of 2.82, which were significantly higher than those found in the benign tumor group (LDH1, 15.2%: H/M ratio, 1.05). In cases of adenocarcinomas, the LDH5 value was 27.2%, compared to 15.7% in cases of benign tumors. Of 28 patients with adenocarcinoma, 15 patients (53.6%) were positive for this elevation. The decline in total LDH activity and elevation of H/M ratio were observed as a general tendency in patients satisfactorily responding to treatment. ALP and ALP isozyme. The malignant tumor group displayed higher values for both total ALP activity and HSAP in ascitic fluid, as compared with the benign tumor group. In the malignant tumor group, alpha 2 and alpha 2-beta regions were prominent in the isozyme pattern and the isozymes of the same regions remained even after inactivation by heat. The total activity decreased significantly in the responders to treatment. TP, alpha 1-AT, alpha 1-AG, alpha 2-M and IgG. The ascitic fluid levels of alpha 1-AT, alpha 2-M and IgG did not significantly differ among the group of patients with germ cell tumors, the group of patients with ovarian gonadal stroma and the group of patients with benign tumors. In the adenocarcinoma group the alpha 1-AT and alpha 2-M levels were higher than those in the benign tumor group. The ascitic fluid alpha 1-AG level and alpha 1-AG/TP ratio were elevated in tumors of germ cell origin and in adenocarcinomas; they tended to correlate with the degree of malignancy of the tumor. The results of the present study suggest that simultaneous measurement of the ascitic fluid levels of LDH isozymes, ALP isozymes, alpha 1-AG, alpha 1-AT, alpha 2-M and IgG may play a potential adjunctive role in providing information for diagnostic differentiation between benign and malignancy, estimation of the histologic type and extent of neoplastic growth, evaluation of the therapeutic response and prediction of the clinical progress.

Early diagnosis is difficult in ovarian cancer and the prognosis is unfavorable even in stage I case. A total of 131 cases with stage I ovarian carcinoma were treated at our institution, 73 were stage Ia, 13 were stage Ib, 45 were stage Ic and 39 were LPM. To define the criteria for selection of therapy, we retrospectively reviewed the stage I ovarian cancer. The results were as follows: The best survival rate was demonstrated in 96% of LPM cases followed by 73% of endometrioid adeno-carcinoma. Cases with rupture of capsule and with ascites at surgery influenced the 5 year survival rate. We observed no difference in survival rate between the conservative operation (unilateral salpingo-oophorectomy) group and the complete operation (bilateral salpingo-oophorectomy and total hysterectomy) group. Those who had received postoperative chemotherapy showed the longest survival rate of 86%. Evaluation of deaths; 9 of 21 with stage Ic died within 12 months after surgery, and 4 of 7 with stage Iai between 1 and 3 years. The analysis has shown the importance of adequate postoperative treatment and of strict follow-up to guard against recurrence of malignancy in patients with ruptured tumor capsules as well as in those with ascites.

Most malignant ovarian tumors metastasize by peritoneal dissemination and have a poor prognosis. Few studies have been made to determine how free ovarian tumor cells act on the peritoneum and become lodged and proliferate therein and much still remains to be clarified concerning this issue. In the present study, we transplanted 2 X 10(6) cells of JOHYL-1 strain established from an atypical dysgerminoma into the peritoneal cavity of nude mice observed serially morphological changes in the peritoneum resulting from tumor cell dissemination both by light microscopy and SEM. The findings thus obtained may be summarized as follows: From 5 to 7 days after intraperitoneal transplantation of tumor cells, mesothelial cells of the peritoneum began to swell, with the intercellular boundaries becoming distinct. Microvilli of the mesothelial cells increased in number, forming a mesh-like structure, and in some places were found to be in direct contact with a tumor cell. From 10 days after tumor cell transplantation onwards the mesothelium showed enlarged intercellular spaces in some places, and at these sites tumor cells were seen to have adhered. On other sites mesothelial cells were being partially lost. From 11 days after being transplanted, the tumor cells started proliferating and infiltrating in the muscle layer. Concerning the site of tumor cell implantation, evidence was obtained showing that tumor cells adhered to intercellular spaces of mesothelial cells, and/or in defects formed on connective tissue by a loss of mesothelial cells. The study thus demonstrated a salient usefulness of the JOHYL-1 ascites type cell line, with a reliably great capacity for growth in vivo, as an experimental model for the study of peritoneal dissemination of tumor cells.