© 1998 AlphaMed Press Adjuvant Chemotherapy for Resected Non-Small Cell Carcinoma of the Lung: Why We Still Don't KnowMultidisciplinary Thoracic Oncology Program, Divisions of Hematology/Oncology and Thoracic Surgery, Departments of Medicine, Surgery and Biostatistics, School of Medicine and Public Health, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA Correspondence: Mark A. Socinski, M.D., CB# 7305, University of North Carolina, Chapel Hill, NC 27599-7305, USA. Telephone: 919-966-4431; Fax: 919-966-6735; e-mail: socinski{at}med.unc.edu
The role of adjuvant chemotherapy in resected non-small cell carcinoma of the lung (NSCLC) remains controversial. A critical review of the 11 cisplatin-based randomized trials addressing this issue was performed using methodology adapted from the CONSORT statement. The 11 trials were divided into those that included predominantly node-negative patients (n = 5) and those that included predominantly node-positive patients (n = 6). In the node-negative trials, which included 1,084 evaluable patients, no evidence of heterogeneity of treatment effect between the trials was found. The composite five-year survival rate for chemotherapy patients was 61% versus 55% for control patients, which reached marginal significance (p = 0.06). In the node-positive trials, which included 880 evaluable patients, a marginal lack of homogeneity of treatment effect between trials was found (p = .013). The composite two-year survival rate for chemotherapy patients was 48% versus 40% for control patients, which reached marginal significance (p = 0.06). Although not definitive, these trials suggest a benefit to postoperative adjuvant chemotherapy in resected NSCLC. The cumulative experience of the 11 trials is notable for: A) the small number of patients; B) heterogenous patient populations; C) substandard chemotherapy regimens; D) inadequate chemotherapy delivery, and E) less than optimally executed clinical trials. The 11 trials are discussed in detail, and recently completed and ongoing trials of adjuvant chemotherapy in resected NSCLC are reviewed. Key Words. Non-small cell lung cancer • Adjuvant chemotherapy
Non-small cell lung cancer (NSCLC) remains the leading cause of cancer death in both men and women [1]. Surgical resection in the early stages of disease results in long-term survival in the majority of patients. However, up to 30% of Stage I and 50% of Stage II patients will die despite surgery [2, 3]. The postoperative prognosis depends on such factors as T stage of the primary tumor and nodal status [4]. The vast majority of relapses following a curative resection are systemic in nature, with local recurrence representing only a minority of cases [5, 6]. Adjuvant radiotherapy has been shown to reduce the incidence of local recurrences; however, it does not improve survival [7]. Given these findings, the strategy that would have the greatest impact on mortality is effective postoperative chemotherapy that significantly reduces the occurrence of systemic relapse. Although postoperative adjuvant chemotherapy improves survival in several solid tumors, its role in NSCLC remains controversial [8]. A recent meta-analysis suggests that early trials which employed alkylating agents in the postoperative setting have a detrimental effect on survival [9]. In the cisplatin era, 11 randomized trials have been reported [10-20]. The patient populations studied in these trials have varied from Stage I to Stage III, and many of the trials were designed and carried out in the early to mid-1980s, employing chemotherapy regimens and supportive care measures reflective of that time period. The recent meta-analysis [9] has suggested a reduction in the odds ratio for death in those trials employing postoperative cisplatin-based adjuvant chemotherapy. However, it is generally believed in the oncologic community that adjuvant chemotherapy has no role in the management of curatively resected NSCLC [21]. We believe that a lack of sufficient data exists to fully resolve this question rather than that the existing data sufficiently exclude a positive role of adjuvant chemotherapy in curatively resected NSCLC. After all, absence of proof is not proof of absence. The purpose of this review is to describe and critically analyze the published and ongoing trials of adjuvant cisplatin-based chemotherapy in resected NSCLC.
The studies included in this review were obtained by searching the English language literature in Medline from 1980 to the present. The following keywords were entered: non-small cell lung cancer, adjuvant chemotherapy, randomized trial. Only completed and published randomized trials using platinum-based regimens after attempted curative resection of non-small cell lung cancer were included in the analysis. Additional studies were obtained from reference lists of the above papers, review articles, and the authors' review of pertinent medical journals. Abstracts were not included since they lacked sufficient detail for careful analysis. Eleven studies were identified. Each study was examined for the number of patients enrolled, balance of control and chemotherapy arms with respect to prognostic factors, statistical methods, statistical significance, chemotherapy regimen employed, compliance with treatment regimens, reasons for lack of compliance, toxicity and overall survival.
A methodologic scoring system was developed to evaluate the quality of the design and to report the results of the trials. The criteria used were adapted from the CONSORT statement, which applies to randomized clinical trials focusing on survival data [22]. The 13 criteria selected by the four authors (Table 1
For this review, the trials were divided into those that included predominantly node-negative patients (defined as 60% node-negative patients entered into the trial) and those that included predominantly node-positive patients (defined as 60% node-positive patients entered into the trial).
Completeness and Quality of Reporting
Statistical Methods An overall assessment of the treatment effect from the studies examined in this article was made using the random effects model of DerSimonian and Laird [23]. A test for homogeneity of the relative odds of survival across the studies was done using the statistic Qw from that article. The survival rates at two and five years were either obtained directly from the study or were estimated from the Kaplan-Meier curves. Unfortunately, sufficient information regarding the censoring of patients who did not die was not provided in the papers. Thus, we assumed that all censoring occurred after the time point of interest. While this is not likely to be true, this provides us with an overall strength of the combined data if the survival rate estimates are accurate and full follow-up did occur. As such, it provides us with the greatest possible information from the different trials for the sample sizes used.
Predominantly Node-Negative Trials
Wada et al. [10] randomized 323 completely resected NSCLC patients to either cisplatin, vindesine, Uft (CVUft), Uft alone, or observation (see Table 3 In 1995, the Study Group of Adjuvant Chemotherapy for Lung Cancer in Japan published a trial [11] with a similar chemotherapy arm as in the Wada trial [10]. This study compared cisplatin, adriamycin, and Uft (CAUft) versus observation alone following curative resection in 309 patients. Compliance in this study was not well reported. It was noted that 14.9% of patients had chemotherapy "interrupted" at some point, although specific data regarding the reasons for interruption and mean total dose received were not reported. The trial did not find a statistically significant survival difference in the chemotherapy group versus control (p = 0.35). However, patients enrolled in this trial were not stratified for prognostic factors and the CAUft arm had significantly more advanced pathological lymph node stage than the control group. When the authors adjusted for this variable, CAUft did confer a significant survival advantage at five years when compared to controls (p = 0.044).
In 1993 Feld et al. [12] reported a trial comparing cyclophosphamide, adriamycin, and cisplatin (CAP) versus observation alone following complete resection of T1N1 or T2 N0 disease (Table 3 In 1992, Niiranen et al. [13] published results on 110 patients randomized to receive either adjuvant CAP or observation following surgery. Fifty-seven percent of the patients on the CAP arm received the planned therapy, with 70% of patients receiving at least three cycles. The timing of the chemotherapy received relative to the planned schedule was not reported. Thirty percent of patients in the CAP arm refused treatment at some point and 13% received no chemotherapy at all (22% of patients refused because of nausea and vomiting). The CAP arm had a better survival (p = 0.05) with a five-year survival rate of 67% in the CAP arm versus 56% in the control arm. The groups were well balanced in terms of prognostic factors, including pathological T and N stage, gender, and histological subtype. However, more patients underwent pneumonectomy in the control population (22 versus 11 patients). Patients who underwent pneumonectomy had a significantly worse outcome than patients undergoing lobectomy (p = 0.002), representing a possible bias against the control group. The five-year survival rate for those patients undergoing lobectomy was 74% in the CAP group and 64% in the control group (p = 0.24).
Ichinose et al. [14] published a trial in 1991 comparing three cisplatin-based chemotherapy arms with observation following curative resection. The chemotherapy arms included CAP with mitomycin, cisplatin-vindesine, and cisplatin-adriamycin-pepleomycin (Table 3
Predominantly Node-Positive Trials
Dautzenburg et al. [18] reported a randomized trial of 267 patients who underwent complete resections. Patients were randomized to adjuvant radiotherapy (60 Gy in six weeks) or three courses of cyclophosphamide, doxorubicin, cisplatin, vincristine, and lomustine followed by the same course of radiotherapy (Table 4 A study by Pisters et al. [17] in 1994 reported a randomized trial of radiotherapy plus or minus vindesine and cisplatin in 72 N2 patients having undergone surgical resection. Sixty-one percent of the patients had a complete resection, while 39% were incompletely resected. (No definition for an "incomplete resection" was given). All patients received mediastinal radiation (40 Gy), and patients with incomplete resections received intraoperative brachytherapy (125I implants). The groups were well balanced for T stage, histology, performance status, and extent of resection. Thirty-six patients were randomized to receive chemotherapy. Only 13 patients (36%) received all four doses of cisplatin. Ninety-two percent of the patients received the planned dose of external beam radiation, and 71% of eligible incompletely resected patients received implants. Reasons for noncompliance were not reported in detail. No significant survival advantage was found for either arm. This trial was initially designed to enroll 50 patients per arm; however, it was stopped early because of "noncompliance with the randomization process." The study had little power to identify either a benefit or a detriment to chemotherapy in this setting. Ohta et al. [15] in 1993 reported a randomized trial of 209 Stage III patients receiving either postoperative cisplatin and vindesine or observation alone, 181 of whom were analyzed. All patients underwent a complete surgical resection. The patients were well balanced between treatment arms except for age, with significantly older patients in the control arm (56 versus 59 years, p = 0.05). There were fewer patients with N2 disease and more patients with T3N0/1 in the control arm than in the chemotherapy arm. Although this tended to benefit the control arm, these differences did not achieve statistical significance. Only 41% of patients received all three cycles of chemotherapy as planned. The average cumulative dose was reported to be 68% of the planned dose. The most frequent reason for patients not receiving the second cycle was patient refusal (occurring in 43% of cases). Survival did not significantly differ between the two groups (p = 0.86). A multivariate analysis showed that advanced pathologic N stage was associated with a poor outcome. Survival for pN0 was 62%, pN1 44% and pN2 29% (p = 0.01). Given this finding, it is somewhat disconcerting that there were more patients with N2 disease in the chemotherapy arm. Also, this trial was designed to detect a 20% increase in the three-year disease-free survival in patients receiving postoperative chemotherapy but was stopped slightly short of the planned accrual of 100 evaluable patients in each group. Lad et al. [19] published a trial of 172 patients with locally advanced, incompletely resected NSCLC randomized to receive radiation therapy (40 Gy) plus or minus six cycles of CAP. One hundred sixty-four patients were eligible for analysis. There were significantly more N1 patients in the chemotherapy arm than in the control (20 versus 10, p = 0.03). Only 51% of patients received all six cycles. Reasons for noncompliance were not provided. The survival rate at one year was 68% for the chemotherapy arm versus 54% for the radiation arm (p = 0.02); however, the death rates did not differ after the first year. The study examined both recurrence and death rates on a rate per person per year and found that the chemotherapy group had significantly lower recurrence and death rates per person than the radiation alone arm during the first year. Holmes et al. [20] randomized 141 patients with either Stage II or III adenocarcinoma or large-cell undifferentiated carcinoma to either four cycles of CAP chemotherapy or intrapleural BCG/levamisole/isoniazid. One hundred thirty patients were eligible for analysis. The survival at two years was 41% for the chemotherapy arm versus 30% in the immunotherapy arm (p = 0.08). Compliance in the chemotherapy arm was poor, with 24% of patients receiving no chemotherapy at all. The reported average cumulative dose was 58% of the planned dose. Reasons for noncompliance were not specified, although 87% of patients suffered gastrointestinal toxicity and 48% hematologic toxicity. The two groups were reportedly well balanced for prognostic factors; however, the control arm had significantly more T3 disease than the treatment arm (p = 0.024). Adjustment for T status as well as stage and performance status did not significantly alter their results.
Kimura et al. [16] reported a small series of adjuvant immunochemotherapy following complete resection of Stage II and III patients with NSCLC. A total of 82 patients were enrolled according to the treatment arms in Table 4
Why We Still Don't Know
In the recent meta-analysis [9], trials were divided between those that included either of the following:
In the former group, 1,394 patients were analyzed and the overall hazard ratio favored chemotherapy (0.87), resulting in a reduction in the risk of death of 13%. The absolute benefit, which was 3% at two years and 5% at five years, was not statistically significant. In the latter group, 668 patients were analyzed and the overall hazard ratio again favored the chemotherapy group (0.94), resulting in a reduction in the risk of death of 6%. Again, the absolute benefit, which was 2% at two years and 5% at five years, was not statistically significant.
The small number of patients (2,062) included in the NSCLC meta-analysis limits the statistical power of that analysis. In contrast, the meta-analysis examining the effect of adjuvant chemotherapy in breast cancer had approximately 75,000 patients involving 31,000 recurrences and 24,000 deaths [25]. In the breast cancer meta-analysis, a 6% improvement in 10-year survival was demonstrated for chemotherapy. Individually, most of the trials in either breast or colon cancer that have shown a benefit to adjuvant chemotherapy have included substantially more patients than the trials in NSCLC summarized here. As noted in Tables 3 and 4
Drug delivery, including both dose and dose intensity, was also inadequate in the majority of studies. The dose of cisplatin in five of the 11 studies was
A comment about the nature of the disease and its treatment is also appropriate. Patients undergoing a major thoracic surgical procedure are often somewhat compromised by that procedure. Although hospitalization times for lobectomy or pneumonectomy range from 4 to 14 days, patients require additional time as outpatients to fully recover. One of the tenets of adjuvant chemotherapy is that the treatment be initiated within a month or so of the curative operation. Since effective therapy in NSCLC is currently considered to be cisplatin-based, patients are exposed to the potential toxicity of these regimens while in a somewhat compromised state. This contrasts sharply to the adjuvant treatments for breast or colon cancer, where the operations are less compromising and the chemotherapy regimens less toxic, thereby allowing more effective delivery. Indeed, we have noted the poor compliance in the 11 trials we have described. Recent advances in supportive care during chemotherapy should greatly enhance compliance. Thus, we believe that the opinion of many physicians that adjuvant chemotherapy is not effective in resected NSCLC is unwarranted.
Current Ongoing Trials of Adjuvant Chemotherapy in NSCLC
The National Cancer Institute of Canada (NCI-C) has initiated a trial in Stage I (T2N0) and Stage II (T1-2N1) completely resected NSCLC patients (BR10). This trial randomly allocates patients to either observation alone or four cycles of vinorelbine and cisplatin. This trial is also prospectively collecting tissue samples to identify important biologic prognostic factors. Patients entered onto this trial are stratified by nodal status (N0 versus N1) and whether a ras mutation is present in their tumor. The primary endpoint is survival. The study is designed to detect an absolute improvement of 10% survival at three years, with an expected 60% survival rate in the observation arm and an exponential survival distribution. In order to have an 80% chance of detecting this difference in overall survival using a log-rank test, with a one-sided 5% alpha level test, 600 patients will need to be accrued over approximately five-years. Both the Southwest Oncology Group (SWOG) and the Eastern Cooperative Oncology Group (ECOG) have elected to participate with the NCI-C in completing this very important trial. The Montreal Multicenter Trial enrolled completely resected patients from 1984 to 1992, accruing 430 patients. Patients without lymph node invasion were randomized to observation alone versus vindesine/cisplatin, while patients with lymph node involvement received post-operative TRT with or without vindesine/cisplatin. This study has been published in abstract form only and no survival data were given. The investigators also examined predictors of relapse such as lymph node metastases, vascular invasion, chemotherapy dose intensity, and the presence of p53 abnormalities. The Adjuvant Lung Project Italy (ALPI) trial is a randomized trial for Stages I, II, and IIIA patients who have undergone a curative resection. Patients are randomized to postoperative mitomycin, vindesine, and cisplatin (MVP) versus observation with TRT at the discretion of the treating physician. The study is designed to detect a 20% reduction in mortality following adjuvant MVP with 80% power at the 5% level of significance. It is estimated by the investigators that 1,500 patients will be required, and approximately 550 patients were enrolled onto the study as of May 1997. The European Organization for the Research and Treatment of Cancer (EORTC) is also participating in this study. The International Adjuvant Lung Cancer Trial (IALT) is a large multicenter randomized trial currently being conducted worldwide. This trial will assess the impact of three or four cycles of cisplatin-based chemotherapy on the survival in curatively resected Stages I, II and IIIA NSCLC. The trial will accrue approximately 3,000 patients. A reduction in mortality of 5%-10% in curatively resected NSCLC is the assumption used in the design of this trial. Given the planned number of patients to be accrued, this trial will have substantially more statistical power than currently published trials of adjuvant therapy in NSCLC. The British Thoracic Society is conducting The Big Lung Trial (BLT) examining the impact of three cycles of cisplatin-based chemotherapy on the survival of curatively resected NSCLC. Patients may also receive postoperative radiation therapy. In patients undergoing surgery alone, 4,000 will be randomized to receive cisplatin-based chemotherapy or observation. This will be sufficient to detect a 5% improvement in five-year survival (50% to 55%) with at least 90% power. In patients undergoing surgery plus radiotherapy, 2,500 patients will be randomized to receive cisplatin-based chemotherapy or observation. This will be sufficient to detect a 5% improvement in five-year survival (20% to 25%) with at least 90% power. The total number of 6,500 patients to be included in this trial will make it the largest trial to date examining the role of cisplatin-based chemotherapy in adjuvant therapy of NSCLC. The CALGB has recently activated a trial in Stage I NSCLC including only T2N0 patients. The randomization in this study is between adjuvant carboplatin/paclitaxel (four cycles) and observation. The primary objective of the study is to determine a survival benefit of the chemotherapy. The study is designed with an 80% power to detect a 13% increase in the five-year survival and will require 500 patients. It is anticipated that accrual will be completed in approximately three years.
Our analysis suggests that there may be a survival benefit to curatively resected patients who receive adjuvant cisplatin-based chemotherapy. However, the studies reported to date do not yield sufficient data to definitively conclude this. These studies suffer from small numbers of heterogeneous patient populations, suboptimal chemotherapy, inadequate chemotherapy delivery, and very often incomplete accrual. Current ongoing trials have been designed to accrue substantially larger numbers of patients and will hopefully meet their accrual goals. Moreover, they utilize modern cisplatin-based regimens and modern standards of supportive care, thereby providing more reliable data on the effect of adjuvant chemotherapy in curatively resected NSCLC. The recent meta-analysis [9] suggested a 6% improvement in five-year survival in early stage NSCLC from the use of chemotherapy as an adjunct to surgery. Using incidence and percent distribution figures from 1997 [1], approximately 30,000 patients will undergo a curative resection for early stage NSCLC in the United States. A 6% improvement in five-year survival would result in approximately 2,000 lives saved as a result of chemotherapy if this 6% figure is real. Although current reported data are suggestive, it does not definitively tell us that adjuvant chemotherapy should be the standard of care. Given the large number of lives at risk, all eligible patients should be placed on adjuvant chemotherapy trials to help answer this very important question.
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