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Ann Thorac Surg 1999;68:1821-1826
© 1999 The Society of Thoracic Surgeons
a Department of Thoracic Surgery, Korea Cancer Center Hospital, Seoul, South Korea
b Department of Radiation Oncology, Korea Cancer Center Hospital, Seoul, South Korea
c Department of Diagnostic Radiology, Korea Cancer Center Hospital, Seoul, South Korea
d Department of Pathology, Korea Cancer Center Hospital, Seoul, South Korea
e Department of Internal Medicine, Korea Cancer Center Hospital, Seoul, South Korea
Address reprint requests to Dr Zo, Department of Thoracic Surgery, Korea Cancer Center Hospital, 215-4, Gongneung-Dong, Nowon-Ku, Seoul, 139-706, Korea
e-mail: jaylzo{at}kcchsun.kcch.re.kr
| Abstract |
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Methods. This study was designed as a randomized, blinded, two-armed study with operation and adjuvant radiotherapy in one arm, versus operation and adjuvant mitomycin C (10 mg/m2), vinblastin (6 mg/m2), and cisplatin (100 mg/m2) (MVP) chemotherapy in the other arm. We assigned 57 resected patients with pathologic proven stage II non-small cell lung cancer to the groups according to our eligibility criteria.
Results. The most common pattern of recurrence was distant metastases, and nearly all the recurrences (17 of 18 patients) in both groups were found within 2 years after operation. The rates of the locoregional and distant metastases were 3.6% and 46.4% in the adjuvant radiotherapy group and 6.9% and 10.3% in the adjuvant chemotherapy group (p = 0.018). The 5-year disease-free survival rates were 52.0% in the adjuvant radiotherapy group and 74.0% in the adjuvant chemotherapy group (p = 0.16, log-rank test). The 2-year, 5-year, and 6-year survival portions were 60.3%, 56.5%, and 28.3% in the adjuvant radiotherapy group, and 82.8%, 70.1%, and 60.1% in the adjuvant chemotherapy group (p = 0.01, p = 0.17, and p = 0.03, Z-test). The difference of the actuarial survival between these two groups was somewhat significant (p = 0.09, log-rank test).
Conclusions. Our results suggest that the addition of adjuvant MVP chemotherapy may reduce the distant metastasis rates and prolong the survival of the surgically resected stage II nonsmall-cell lung cancer patients.
| Introduction |
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| Patients and methods |
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Patients assigned to the adjuvant chemotherapy group received mitomycin C (10 mg/m2), vinblastin (6 mg/m2), and cisplatin (100 mg/m2) (MVP). The treatment began within 30 days after operation and was repeated every 3 weeks for a total of three cycles. When necessary, dose reduction was done at the discretion of the medical oncologist.
Eligibility
Patients were required to undergo complete resection of the tumor. Also, completely resected lymph nodes from the subcarinal, paratracheal, hilar, and bronchopulmonary areas were required for pathologic staging. Only the patients with definite diagnosis of NSCLC by histologic examination and at pathologic stage T12N1M0 were accepted for the study. The surgeons, after complete total resection of the tumor, had to confirm that the resection margins were microscopically free of tumor and that there was no known microscopic intrathoracic disease remaining. No known metastases in or beyond the mediastinum could exist. Patients who had received previous chemotherapy, immunotherapy, or thoracic irradiation were excluded. Patients in the following groups were considered ineligible: more than 70 years of age; inadequate performance status, pulmonary function test, liver function test, cardiac functions, and renal functions for adjuvant therapy. Patients who recovered without any serious complication within 2 weeks after operation were considered eligible for this study. Two to 3 weeks after the radical operation, patients who fulfilled the entry criteria were randomly assigned to the adjuvant radiotherapy arm or the adjuvant chemotherapy arm. Written consent was obtained in accordance with the human subject guidelines at Korea Cancer Center Hospital.
Patient characteristics
Between April 1989 and June 1996, 57 patients with stage II NSCLC entered into this study. Each patients clinical staging included history and physical examinations, complete blood counts, chemistries, electrocardiograms, and pulmonary function tests. Radiologic testing included chest radiograph and computed tomography of the chest and upper abdomen. Patients also received bronchoscopy, abdominal sonography, and radionuclide bone scanning. Magnetic resonance imaging of the brain was not obtained routinely in all patients before operation; however, it was performed if clinically indicated. When indicated by these tests, mediastinoscopy with lymph node biopsy was performed to exclude contralateral mediastinal lymph node involvement. The disease was staged postoperatively by the international pTNM criteria for cancer staging adopted by the American Joint Committee for Cancer Staging (4th edition) [1]. The pathology reports of all patients were reviewed carefully to ensure that the resection was complete, that no residual tumor, gross or microscopic, was left behind, and that no involved mediastinal lymph nodes were present before enrolling the patients into this study.
Evaluation
All patients were followed up after being discharged from the hospital. Follow-up examinations were scheduled monthly or bimonthly for the first 6 months, quarterly for the following 18 months, and semiannually thereafter. The parameters recorded during the follow-up were history and physical examination, blood chemistry, chest roentgenogram, chest computed tomography, radionuclide bone scanning, and abdominal sonography. Bronchoscopy was also done when necessary. Chest computed tomography, including the upper abdomen, was scheduled every 6 months for 5 years. The number of days from operation to the detection of the site of first confirmed recurrence constituted the length of the disease-free interval. Also, survival was calculated as the time from the date of operation until death or last contact with the patient. Toxicity of adjuvant therapy was scored according to the Radiation Morbidity Scoring Criteria (Radiation Therapy Oncology Group) and the World Health Organization criteria [5, 6]. The results were based on an analysis performed on February 28, 1998, about 9 years after the initiation of this study. The mean time from randomization to analysis was 42.4 months.
Statistical methods
The actuarial survival and the disease-free survival were plotted as curves using the Kaplan-Meier method. Comparison of the survival curves was made with the log-rank method. Z-test was used to compare the 2-year, 5-year, and 6-year survival proportions [7]. For comparison of the intergroup differences, the
2 test was used. p values of less than 0.05 were considered statistically significant.
| Results |
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Disease-free survival and relapse pattern
We have defined local recurrence as evidence of tumor within the same lung or at the bronchial stump and regional recurrence as the clinically manifested disease in the mediastinal nodes despite the mediastinal lymph node dissection during the original operation, lymph node metastasis in contralateral lymph nodes, or lymph node metastasis in the supraclavicular regions. Distant recurrence was defined as the disease in the contralateral lung, distant lymph nodes, or distant organs. Eighteen patients (31.6%) have documented recurrence after treatment (13 patients in the radiotherapy group and 5 in the chemotherapy group, p = 0.018). The median time of recurrence was 12.6 months (13.4 months in the radiotherapy group, 10.4 months in the chemotherapy group; range, 1.7 to 54.3 months). Only 2 patients with documented recurrences were alive at the time of this analysis. The pattern of recurrence was different according to the adjuvant therapy. Although there was only one local recurrence, we detected 13 sites of distant metastases in 12 patients in the radiotherapy group. In the chemotherapy group, there were 2 cases of local recurrences and only 3 cases of distant metastases. The brain was the most common site of metastasis. There were six brain metastases in the radiotherapy group, but none in the chemotherapy group. The differences in the incidence of overall recurrence or distant metastasis were significant (p < 0.05; Table 2). The recurrence rate/year was particularly high in the first 2 years. All the recurrences except one developed within 2 years after operation. The probability of recurrence in the first year after operation was 32.1% in the radiotherapy group and 10.3% in the chemotherapy group. The probabilities of recurrence in the first 2 years were 42.9% and 17.2%, respectively. The 5-year disease-free survival rates were 52.0% in the radiotherapy group and 74.0% in the chemotherapy group (p = 0.16, log-rank test; Fig 1). The type of operation and histology did not play a statistically significant role in the total incidence of recurrence.
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Hematologic toxicity was not a serious problem; nevertheless, it was observed in 19 patients in the adjuvant chemotherapy group. Ten patients had grade 1 leukopenia (World Health Organization classification) [6]. Three patients had grade 2 anemia and 13 had grade 1 anemia. Thrombocytopenia was observed in 5 patients (grade 1). Nonhematologic side effects occurred in 18 of the patients who received chemotherapy. Cisplatin-induced emesis was the most disturbing side effect. Two of the 18 patients with nonhematologic side effects experienced grade 3 (World Health Organization classification) nausea and vomiting, and 15 patients had grade 1 or 2 nausea and vomiting. However, they were somewhat controlled with the antiemetics in use at the time of the study. Two patients suffered grade 2 hepatotoxicity, and 1 patient suffered lung abscess, which developed after chemotherapy. Only 1 patient suffered grade 1 peripheral neuropathy. There was no death related to the adjuvant chemotherapy.
| Comment |
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In the past decade, many investigators have insisted that adjuvant therapy is needed once a nodal involvement is present, even in the favorable subgroup of patients with NSCLC. Although Martini and colleagues [9] reported that there was no improvement in survival with the use of adjuvant therapy, Ferguson [13] and Newman [14] and their colleagues have insisted that resection in combination with adjuvant radiotherapy and chemotherapy offered improved median survival over resection alone in patients with stage II NSCLC. However, they were all studied in a retrospective manner with limitations of small numbers of patients. Recently, a prospective study from Finland [15] has shown a statistically significant prolongation of survival in T13N1M0 NSCLC with using adjuvant chemotherapy. However, there are no prospective studies confined just to stage II disease. Therefore, we decided to start this study in 1989.
In such a prospective study, a number of issues can be raised with regard to the efficiency of adjuvant chemotherapy in completely resected NSCLC. One of those is the choice of chemotherapy. The use of multidrug regimens including cisplatin has produced prolongation of disease-free survival, but until recently, no overall survival benefit has been shown. However, the Eastern Cooperative Oncology Group reported that the overall response rate of advanced NSCLC to MVP was superior to three other regimens [16]. Also, a randomized study in stage IV patients by the National Cancer Institute of Canada has shown that the commonly used combination of cisplatin and vindesine is superior to the CAP chemotherapy (cyclophosphamide, adriamycin, and cisplatin) [17]. These studies, as well as a number of neoadjuvant chemotherapy studies, reporting response rates of 40% to 70% for MVP regimen have encouraged the use of the MVP regimen in this study [18]. Another problem in this study was the selection of the control group. We considered the adjuvant radiotherapy group as the control group, although it was not a standard treatment. We based this decision on the end results of the vast and randomized study of the Lung Cancer Study Group [4]. The other reason for using the control group was that a three-group study including the operation-only group was too time consuming for a single institute study, because patients with pathologically proved stage II disease represented only less than 5% to 6% of the total lung cancer population [19, 20]. Also, we wanted to compare the pattern and rate of recurrence in relation to the choice of adjuvant therapy.
In this study, patient selection and randomization were stringent. The radiotherapy group and the adjuvant chemotherapy group were well balanced with regard to the well-known prognostic factors such as the pathologic stage, histologic subtype, and the operative method.
The recurrence rate in the first 2 years after operation was particularly high. It was observed that almost all recurrences (17 of 18 recurred cases) developed within the first 2 years. We also found that the locoregional recurrences were rare (Table 2), and that they were not important factors in selecting adjuvant therapy for completely resected stage II NSCLC. On the other hand, majority of the first observed recurrences (84.2%) were located at a distant site. There was a significant difference in the overall recurrence rate dependent on the adjuvant therapy, especially in distant metastases. The adjuvant chemotherapy group had significantly fewer distant metastases than the radiotherapy group (p = 0.018). Therefore, it seems very likely that adjuvant chemotherapy may prevent the development of micrometastasis, and decrease the incidence of distant metastasis, which is the most important prognostic factor in stage II NSCLC after operation. In addition to this, our findings agree with the results of other researchers in that the most frequent site of metastasis was the brain in early NSCLC after operation [2, 9, 10]. Although there were 6 patients with brain metastases in the 13 recurred patients in the radiotherapy group, there was none in the chemotherapy group. The median time of detection after operation in the 6 patients with brain metastases was 12.4 months (range, 8.4 to 21.5 months). Although it remains an open question as to the exact mechanism for prevention of brain metastases in the chemotherapy group, our results can be explained by the fact that blood vessels formed by metastatic neoplasms are often defective, and that tumor-induced blood vessels have imperfect bloodbrain barrier in the brain [21, 22].
The median survival period was 61.9 months in the radiotherapy group, but was not reached in the chemotherapy group. Continuous follow-up has shown that the mean survival time has remained stable, and the estimated 2-, 5-, and 6-year survival rates were 60.3%, 56.5%, and 28.3% in the radiotherapy group, and 82.8%, 70.1%, and 60.1% in the chemotherapy group, respectively (p = 0.01, p = 0.17, p = 0.03, Z-test). As mentioned above, the difference in the actuarial survival between our two groups was somewhat significant (p = 0.09, log-rank test).
In this study, there were more cancer-related deaths in the radiotherapy group than in the chemotherapy group (43% to 21%, p = 0.07; Table 3). Therefore, it seems likely that the cancer-related deaths may influence the difference in the actuarial survival in both groups, as the number of noncancer-related deaths was small.
Although adjuvant radiotherapy was reported to protect against local recurrence in several other studies, our data demonstrate that this effect does not translate into a demonstrable overall survival benefit in stage II NSCLC [2]. This is largely because 87% of recurrences were outside the radiation field and possibly because radiation may slightly increase the risks of disease other than cancer. This means that the benefit provided by slightly improved local control of postoperative radiotherapy may often be masked by a severe toxic side effect, and in some patients, having a deleterious effect on survival. In fact, there were 5 patients with radiation pneumonitis (grade 3 to 4) and one radiation-related death in our study. The CAP generation of studies encountered significant problems with patient compliance, in large part, attributable to the high incidence of cisplatin-induced emesis. Also in this study, the main problem throughout the adjuvant chemotherapy was not the hematologic toxicity but the cisplatin-induced nausea. However, it was somewhat controlled by the antiemetics in use at the time of the study. It was very important to increase the number of patients able to undergo the fully-planned chemotherapy.
Although our results cannot provide sufficient justification to recommend postoperative chemotherapy to stage II NSCLC patients because of the limitations of a small number of patients and the control group, it may provide a possibility for postoperative adjuvant chemotherapy as a newly accepted method. In fact, our study suggests that the administration of effective systemic adjuvant therapy may improve the survival of patients with stage II NSCLC, as the systemic recurrences remain the major obstacle in improving the cure rates. Therefore, we believe that systemic adjuvant therapy is needed once N1 lymph node involvement is present, even in the favorable subgroup of patients with NSCLC. At any rate, it is clear that significant improvements in the survival of patients with stage II NSCLC require more effective adjuvant systemic therapy.
| Acknowledgments |
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| References |
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