Kazuya Nakahara

Follow-up study of thymomas with special reference to their clinical stages.

Follow‐up data were obtained for 96 cases of thymoma. The one‐year survival rate was 84.3%, the three‐year 77.1%, the five‐year 74.1%, and the ten‐year 57.1%. The five‐year survival rate of total resection group was 88.9%; that of non‐radically treated group was 44.4%. Clinical stages were defined: Stage I—macroscopically encapsulated and microscopically no capsular invasion; Stage II—1. macroscopic invasion into surrounding fatty tissue or mediastinal pleura, or 2. microscopic invasion into capsule; Stage III—macroscopic invasion into neighboring organ; Stage IVa—pleural or pericardial dissemination; Stage IVb—lymphogenous or hematogenous metastasis. Five‐year survival rates of each clinical stage were 92.6% in Stage I, 85.7% in Stage II, 69.6% in Stage III, and 50% in Stage IV. Recurrence after total resection was found in six of 69 cases. Seven of 13 patients treated by subtotal resection survived more than five years with postopertive radiotherapy.

A Method for Predicting Postoperative Lung Function and Its Relation to Postoperative Complications in Patients with Lung Cancer

We predicted the postoperative forced expiratory volume in 1 second (FEV1) with a formula based on the premise that the total number of subsegments was 42: postop FEV1 = [1 - (b - n)/(42 - n)] (preop FEV1), where n and b are the number of obstructed subsegments and total subsegments, respectively, in the resected lobe. It was assumed that b was 6, 4, and 12 in the right upper, middle, and lower lobes, respectively, and 10 each in the left upper and the left lower lobes. The obstructed subsegments, n, were obtained from the findings on bronchography or bronchofiberscopy or both before operation. The linear regression line derived from the correlation between predicted (x) and measured (y) FEV1 was y = 0.850x + 0.286 +/- 0.296 (standard error) (N = 52; r = 0.821; p less than 0.001). We calculated the predicted postoperative FEV1 in 188 patients with primary lung cancer. The predicted values were corrected with the regression equation just mentioned and then normalized by the patients height and sex (%FEV1(p,c). The correlation between %FEV1(p,c) and the surgical risk was studied. Postoperative respiratory complications were inversely related to %FEV1(p,c), and a significantly high incidence of complications (p less than 0.05) was observed in those whose %FEV1(p,c) was less than 60% of predicted normal. In aged patients (65 years old or more) without complications, %FEV1(p,c) was 67.3 +/- 18.0%; it was 52.2 +/- 12.8% in those with respiratory trouble and 53.3% +/- 9.6% in those with circulatory complications. The difference between groups with and without complications was significant (p less than 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

A tentative tumor–node–metastasis classification of thymoma

To establish a tumor–node–metastasis (TNM) classification of thymoma, 207 thymoma patients seen at the First Department of Surgery, Osaka University, and the Second Department of Surgery, Nagoya City University, were evaluated. Lymphogenous and hematogenous metastases of thymoma were infrequent, but their frequency increased with the duration of the course. Lymphogenous metastasis was observed in few cases, but it was considered to progress from anterior mediastinal lymph nodes to intrathoracic and then to extrathoracic lymph nodes. No particular characteristics were observed in hematogenous metastasis. On the basis of these observations, a TNM classification of thymoma was established and applied it to 207 thymoma cases, but it had little advantage over conventional clinical staging. High percentages of thymic carcinomas and thymic carcinoids were in Stage IVB, and the TNM classification of these tumors was considered to be more useful.

Results of surgical treatment of thymomas with special reference to the involved organs.

OBJECTIVE The purpose of this study is to clarify the significance of the particular involved organ as a prognostic factor and its relation to other previously reported factors. METHODS The prognoses of 194 consecutive patients with thymoma who had undergone complete or subtotal resection were reviewed retrospectively. Survival was evaluated as actuarial freedom from tumor death. Analysis of prognostic factors was performed by the Kaplan-Meier method with the log rank test and Coxs proportional hazards model. RESULTS The Masaoka staging system and involvement of the great vessels were the independent prognostic factors in the entire study group; age, sex, histologic subtype, completeness of resection, association of myasthenia gravis, or involvement of other organs were not factors. The 10-year and 20-year survivals were 99% and 90% in stage I, 94% and 90% in stage II, 88% and 56% in stage III, 30% and 15% in stage IVa, 0% and 0% in stage IVb, 93% and 83% in the absence of involvement of the great vessels, and 54% and 20% in the presence of it. Involvement of the great vessels was also the single independent prognostic factor in the patients with stage III disease although completeness of resection or involvement of other organs were not. The 10-year and 20-year survivals in patients with stage III disease were 97% and 75% in the absence of involvement of the great vessels, and 70% and 29% in the presence of it. CONCLUSION Although the Masaoka staging system is a valuable prognostic factor, the category of stage III is heterogeneous and consists of 2 groups with distinct prognoses depending on involvement of the great vessels.

Prediction of Postoperative Respiratory Failure in Patients Undergoing Lung Resection for Lung Cancer

To evaluate the correlation between predicted postoperative lung function and postoperative respiratory morbidity, 156 patients with lung cancer who underwent resection were classified into four groups based on the degree of postoperative problems: Group 1--no problems (116 patients); Group 2--retention of sputum or atelectasis requiring bronchofiberscopy two or more times (17 patients); Group 3--tracheostomy or mechanical ventilation for more than 2 days or both (14 patients); and Group 4--postoperative death (9 patients). The mean ages of Groups 2, 3, and 4 were significantly (p less than 0.05) higher than the mean age of Group 1. The predicted postoperative lung function (F) was assessed by the formula F = [1-(b-n)/(42-n)] x f, where f is the preoperative vital capacity or forced expiratory volume in one second, b is the number of subsegments of the resected lung lobe, and n is the number of subsegments obstructed by the tumor, which was assessed by the findings on the chest tomogram, on the bronchogram, at bronchofiberscopy, or a combination of these. The total number of subsegments was assumed to be 42. The predicted postoperative % FEV1 was 65.1 +/- 19.3% in Group 1,55.3 +/- 10.6% in Group 2,37.6 +/- 12.1% in Group 3, and 42.3 +/- 18.4% in Group 4. It was significantly (p less than 0.05) different between all the groups except between Groups 3 and 4. All 10 patients with a predicted postoperative % FEV1 of less than 30% were in Groups 3 and 4. We conclude that special attention to postoperative management is needed for patients whose predicted postoperative %FEV1 is lower than 30%.

Thymectomy and malignancy

Three hundred ninety patients who underwent thymectomy for myasthenia gravis (MG) were followed up to investigate the development of associated malignancies. There were 102 patients with thymoma and 288 without thymoma. Malignant neoplasms were detected in ten patients, four of whom already had the tumor at the time MG was diagnosed. Thus, malignancy developed after thymectomy in six patients. Malignant fibrous histiocytoma (MFH) developed in three patients, as well as gastric cancer, gastric leiomyosarcoma, rectal cancer, liver cancer, lung cancer, breast cancer, and thymic carcinoid in one patient each. Nine of the ten malignancies developed in the thymoma group, and only one in the non-thymoma group. The predicted number of patients with malignancy was 2.63 in the thymoma group and 2.65 in the non-thymoma group. Our findings suggest that the presence of thymoma facilitates the occurrence of extrathymic malignancy, and that thymectomy never enhances the occurrence of malignancy but possibly inhibits it.

Clinicopathologic study of thyroid carcinoma infiltrating the trachea

Eighteen patients (10 women and 8 men), ranging in age from 37 to 80 years, with thyroid carcinoma infiltrating the trachea comprised this series. Eleven had primary and 7 had recurrent cases. Total laryngectomy was performed in 4 patients, and tracheal resection was carried out followed by end‐to‐end anastomosis in 13 patients. In one patient, reconstruction was done with Navilles artificial trachea after tracheal resection. Eleven patients were alive after 1 year and 8 months to 6 years and 7 months after the operation. This result was significantly better than that of a group of ten patients without resection of the infiltrated trachea (seven patients died within 6 months). Thus, combined resection of the upper airway improved the prognosis of advanced thyroid carcinoma with tracheal infiltration. Histologic examination of surgical specimens demonstrated well‐differentiated carcinoma in seven patients, poorly differentiated carcinoma in seven patients, undifferentiated carcinoma in three patients, and squamous cell carcinoma in one patient. The result showed a higher frequency of poorly differentiated carcinoma than in the control group of 70 patients without tracheal infiltration.

Antibody to acetylcholine receptor in myasthenia gravis: production by lymphocytes from thymus or thymoma.

In 13 of 17 myasthenic patients without thymoma and all 7 patients with thymoma, thymic lymphocytes produced antibody to acetylcholine receptor (AChR). Lymphocytes from the thymoma itself did not produce AChR antibody except in one patient. The rate of antibody production was higher in patients without thymoma than in patients with thymoma (32.5 and 3.9 fmol/106 cells/week, respectively). The rate of antibody production was related to the serum titer of AChR antibody (r = 0.7, p < 0.001). Enrichment of B cells using a nylon wool column increased the rate of antibody production by thymic lymphocytes 1.3- to 8.0-fold.

Myasthenia Gravis with Thymoma: Analysis of and Postoperative Prognosis for 65 Patients with Thymomatous Myasthenia Gravis

Sixty-five patients with thymomatous myasthenia gravis were investigated. Thymomas were present in 44% of the male patients and 19% of the female patients with myasthenia gravis. The incidence of thymomatous disease in male patients was higher than in female patients in all age groups. Eighty percent of men more than 50 years old and women more than 60 years old had myasthenia gravis with thymoma. Germinal center formation in the thymus of patients with thymomatous myasthenia gravis was positive in 91% and was high grade. The prognosis for patients undergoing extended thymectomy of thymomatous myasthenia gravis was significantly better than in those having transsternal simple thymectomy, but it was worse than the prognosis for patients with nonthymomatous myasthenia gravis. No increase in the rate of remission or palliation was seen one year after thymectomy. It is concluded that early thymectomy is effective in control of myasthenia gravis in thymomatous myasthenia gravis.

Case‐Control Study for Lung Cancer and Cigarette Smoking in Osaka, Japan: Comparison with the Results from Western Europe

In order to clarify the relation between cigarette smoking and lung cancer, a case‐control study was conducted. The case series consisted of 1,376 lung cancer patients (1,082 males and 294 females) who were newly diagnosed and admitted to eight hospitals in Osaka during 1986–88. Smoking histories were compared with those of 2,230 controls (1,141 males and 1,089 females) admitted to the same hospitals during the same period without established smoking‐related diseases. Odds ratios of current smoker versus nonsmoker were 18.1, 1.9, 21.4, and 3.8 for squamous, adeno, small, and large cell carcinoma, respectively, for males, and 9.7, 1.3, 12.1, 3.7, respectively, for females. Compared to the results from previous studies in Japan, the magnitude of the odds ratios for squamous and small cell carcinoma is approaching the level of Western Europe in the late 1970s. Population attributable risk of exsmokers has also been increasing to the level of Western Europe. Among male current smokers, smoking intensity, such as number of cigarettes per day or fraction smoked per cigarette, seemed to have a slightly greater influence on squamous cell carcinoma than adenocarcinoma, while factors associated with the spread of cigarette smoke, such as inhalation, seemed to have greater influence on adenocarcinoma. The difference in the distribution of these smoking characteristics between Japan and Western Europe could not fully explain the difference in lung cancer incidence and distribution of histologic types between the two areas.