Mitsuru Sasako

Treatment Results of Gastric Cancer Patients: Japanese Experience

The Japanese Research Society for Gastric Cancer (JRSGC) was established in 1962, and promoted actively, basic study as well as clinical management of the disease. Leading institutions of Japan, 311 in all, participated in the society; 214 were involved with surgical oncology, 54 medical oncology, 11 radiology, and 32 basic research. In order to standardize the documentation of diagnosis, treatment, and pathological findings, the society published a manual in 1962; “The General Rules for Gastric Cancer Study in Surgery and Pathology” [1]. The manual had peen periodically improved and the 12th edition is now in use. The JRSGC and the National Cancer Center started a nationwide data collection of gastric cancer patients in 1963 using the mannual. Approximately 10 000 new patients had been registered annually from the member institutions. This registration was considered to cover approximately 16% of the gastric cancer patients in Japan. The collected data were analyzed by computer, and the results were published as annual reports (Fig. 1). The results showed the characteristics of gastric cancer as well as the latest situation of diagnosis and treatment of gastric cancer patients in Japan. Using the nationwide database, we revealed the results of gastric cancer treatments in Japan.

Randomized Controlled Trials on Adjuvant Therapy for Gastric Cancer: Japanese Experience

The treatment outcomes of gastric cancer in Japan have steadily improved over the past three decades [1], whereas those in Western countries are rather stable in a depressing status. The improvement in Japan seems to be largely attributable to the increase of early detection and consequent curative resection of the tumor. The impact of chemotherapy has been relatively small, and the results of noncurative resection or nonresectable cases remain poor.

Adjuvant Chemotherapy of Gastric Cancer: JCOG Experience

Results of treatment for gastric cancer in Japan have much improved over the last 20 years. The main reasons could be early detection of cancer and improvement in extended lymph node dissection. Multimodal therapy, including adjuvant chemotherapy, may also contribute to the improvement in prognosis [1]. Since the late 1950s, adjuvant chemotherapies have been routinely incorporated into postoperative therapy for gastric cancer in preventing postoperative recurrences. A review of past trials in Japan and Western countries, however, reveals little evidence of a survival benefit of postoperative adjuvant chemotherapy, though some favorable results have been reported in limited subsets of patients in Japan [2, 3, 4]. On the other hand, two meta-analyses showed statistical significance in terms of life prolongation with postoperative adjuvant chemotherapy [5,6]. To clarify the efficacy of postoperative adjuvant chemotherapy for gastric cancer, the Gastric Cancer Surgical Study Group (GCSSG) in the Japan Clinical Oncology Group (JCOG) [7] has initiated a new trial on the clinical significance of adjuvant chemotherapy.

Computer Assisted Surgery for Gastric Cancer

Lymph node (LN) dissection is an effective procedure in surgical treatment of gastric cancer. For the rational LN dissection, it is essential to know the incidence of metastasis at each LN station and effectiveness of the dissection. In 1984 we created the computer program using our data of 3,785 primary gastric cancer patients. Pre-operatively seven data of an individual patient are input; sex, age, location, macroscopic type, size, depth of invasion, and histological type. The computer informs us the expected 5 year survival rate, incidence of metastasis at all regional LN stations, type of recurrence. Accuracy of the system was very high; false positive was only 14 cases (1.8%) in the prospective study of 774 patients. This system was also evaluated in Germany, and the sensitivity was 100%, specificity was 78%, and accuracy was 89% for N2 compartment.

Non-Anatomical Prognostic Factors for Gastric Cancer Patients: Significance of Tumor Markers

Prognostic significance of non-anatomical factors was studied using data of primary gastric cancer patients treated surgically at National Cancer Center in 10 years period (1976 – 1985). It was notable that Preoperative CEA level showed strong correlation to Stage, curability, and five year survival rate in 1,612 patients, and pre-operative AFP level showed the same correlation in 1,933 patients. By multi-variate analysis of prognostic factors including tumor markers, depth of invasion was the most significant factor, followed by lymph node metastasis, distant metastasis, pre-operative CA 19-9, and lymph node dissection. Tumor marker is one of the important prognostic factors, and can be regarded as Ml in the TNM Classification.

Surgical Resection of the Stomach with Lymph Node Dissection

As gastrectomy is now rarely indicated for benign disease of the stomach, this chapter focusses on gastrectomy for gastric malignancies. For gastric cancers, several types of resection are commonly used. For proximal advanced tumours or large tumours, a total gastrectomy (TG) is usually used. For a distally located tumour which does not involve the proximal third of the stomach, a distal (DG) or distal subtotal gastrectomy (DSG) is the preferred type of gastric resection. In the 1980s, proximal gastrectomy (PG) was for a while abandoned because of the high incidence of reflux oesophagitis and in pursuit of radical surgery. However, with the identification of an increasing number of small T1/2 tumours located near the cardia, interest in the role of proximal gastrectomy has been renewed. For similar tumours in the middle of the stomach, pylorus preserving distal gastrectomy (PPG) is being undertaken in an attempt to improve quality of life after surgery [1].

Metastasis to Minute Lymph Node in Gastric Cancer, Its Significance for Indication of Endoscopic or Local Surgical Treatments

In a recent case of limited gastric resection for early gastric cancer with submucosal invasion, we found metastatic carcinoma in a minute lymph node at the gastric serosa. In a prospective study to determine the incidence of such metastases, we studied 200 consecutive patients. Our data showed that minute gastric serosal lymph nodes occurred in 43 cases(22%). However metastatic carcinoma in early gastric cancer to these nodes was uncommon, occurring in 1 case(2.3%). It is concluded that even if metastasis to minute lymph nodes at the gastric serosa had been previously missed,they would not have affected the data base for the management of early gastric cancer, particularly for endoscopic or local surgical treatment, because of the rarity of metastasis to these lymph nodes. Nevertheless it should be noted that metastasis to minute gastric serosal lymph nodes can sometimes occur.