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* From the Institute of Pathology (Drs. Junker and Langner), Bergmannsheil University Hospital, Bochum, Germany; Department of Thoracic Surgery (Prof. Klinke), St. Raphael Hospital, Ostercappeln, Germany; Institute of Pathology (Dr. Bosse), Osnabrück, Germany; and Department of Hematology (Dr. Thomas), Oncology and Respiratory Medicine, University of Münster, Münster, Germany.
Corresponding author: Klaus Junker, MD, Institute of Pathology, Bergmannsheil University Hospital, Bürkle-de-la-Camp-Platz 1, D-44789 Bochum, Germany; e-mail: klaus.junker{at}ruhr-uni-bochum.de
| Abstract |
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Patients and methods: In a multicenter phase II trial, 54 patients with locally advanced NSCLC received neoadjuvant bimodality treatment (ie, two cycles of ifosfamide, carboplatin, and etoposide, followed by twice-daily radiation up to 45 Gy with simultaneous administration of carboplatin and vindesine). Forty patients underwent resections. Using the corresponding resection specimens of the primary and regional lymph nodes, the following regression grading was established: grade I, no regression or only spontaneous tumor regression; grade II, morphologic evidence of therapy-induced tumor regression with at least 10% (grade IIa) or < 10% (grade IIb) vital tumor tissue; and grade III, complete tumor regression with no evidence of vital tumor tissue. Regression grading then was correlated with the survival time.
Results: Three tumors were classified as regression grade I, 10 were classified as regression grade IIa, 20 were classified as regression grade IIb, and 7 were classified as regression grade III. Patients with tumors of regression grades IIb or III showed significantly longer survival times than those with tumors of regression grades I or IIa (median survival time, 36 vs 14 months, respectively; 3-year survival rate, 52% vs 9%, respectively; p = 0.02). These survival times were also compared for patients who had undergone complete resection (median survival time, not reached vs 23 months, respectively; 3-year survival rate, 56% vs 11%, respectively; p = 0.03). The presurgical clinical response after patients had received neoadjuvant multimodality therapy had no predictive value in assessing the extent of therapy-induced tumor regression in the resection specimen.
Conclusions: After neoadjuvant therapy of patients with NSCLC, the proposed tumor regression grading was of predictive value for long-term survival. Beyond the achievement of complete tumor resection (R0), a therapy-induced tumor regression of < 10% of vital tumor tissue is pivotal for superior long-term outcomes.
Key Words: mediastinal lymph node downstaging neoadjuvant therapy non-small cell lung cancer prognostic factors regression grading
| Introduction |
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| Materials and Methods |
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From April 1992 to September 1995, patients with NSCLC stage IIIA (tumor stage T13N2M0) with histologically confirmed N2 status or stage IIIB (tumor stage T4N13M0/T14N3M0) were enrolled in the study. Patients with involvement of the supraclavicular lymph nodes or who had positive test results for pleural effusion were not eligible. Further requirements were a favorable medical condition (Eastern Cooperative Oncology Group grade, 0 or 1), age range of 18 to 69 years, sufficient bone marrow reserve (leukocyte level, > 4,000 cells/µL; thrombocyte level, > 100,000 cells/µL), and adequate liver and kidney function (bilirubin level, < 1.5 mg/dL; creatinine < 1.5 mg/dL; creatinine clearance, > 30 mL/min). The pretreatment evaluation included a laboratory test parameter profile, bronchoscopy, and image diagnosis, with chest radiograph, CT scan of the thorax, abdomen, and brain, and a bone scan. Mediastinoscopy was performed to assess the mediastinal lymph node status. Patients also were enrolled after an assessment of the mediastinal lymph nodes by means of an exploratory thoracotomy.
Treatment Protocol
Treatment started with two cycles of chemotherapy (the second
cycle started on day 22) with carboplatin (300
mg/m2; day 1), ifosfamide (1,500
mg/m2; days 1, 3, and 5), and etoposide (100
mg/m2; days 1, 3, and 5). The subcutaneous
administration of granulocyte colony-stimulating factor (300 µg/d)
was started on day 6 and was continued until the leukocyte level
exceeded 4,000 cells/µL. Three weeks after the start of the second
cycle of chemotherapy, concurrent radiochemotherapy was commenced. Two
1.5-Gy fractions per day, with an intertreatment interval of at least
6 h, were administered 5 days a week to a total dose of 45 Gy
(days 43 to 61). Carboplatin (100 mg/m2) and
vindesine (3 mg absolute) were administered on days 43, 50, and 57.
Seven weeks, on average, after the completion of combined chemoradiotherapy, patients who remained free of distant metastases were eligible for thoracotomy. Surgery was performed with the objective of achieving complete resection of the tumor (ie, resection margins microscopically free of tumor cells with complete resection) and extensive mediastinal lymph node sampling. Patients with incomplete resections or inoperable tumors received further radiotherapy with conventional fractionation (16 Gy; 2 Gy 5 times per week) [Fig 1 ].
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Regression Grading
The surgical specimens were morphologically analyzed regarding
therapy-induced changes of the tumor tissue. Initially, the
formalin-fixed resection samples were inspected macroscopically. From
the primary lesion, regions with likely vital tumor tissue or former,
now regressively altered, tumor tissue as well as all resected
mediastinal lymph nodes were embedded in paraffin. Depending on the
size of the tumor, up to 58 paraffin blocks were processed
histologically. For further evaluation, histologic slides of the
macroscopically tumor-free surrounding lung parenchyma also were
prepared. Hematoxylin-eosin and van Gieson stains were available for
analysis of the specimens. In order to determine the degree of
tumor regression, the type and extent of the vital tumor tissue, and
the degree of tumor necrosis as well as reactive alterations with foam
cell reaction and fibrosis or scar formation were taken into account.
These findings were classified according to the following regression
grading:
Grade I: no tumor regression or only spontaneous tumor regression in the sections of the primary lesion and mediastinal lymph nodes;
Grade II: morphologic evidence of therapy-induced tumor regression with at least 10% residual tumor cells in the sections of the primary lesion and/or mediastinal lymph nodes presenting more than focal microscopic disease (grade IIa) or < 10% residual tumor cells in the sections of the primary lesion and/or mediastinal lymph nodes presenting focal microscopic disease (grade IIb); and
Grade III: complete tumor regression with no evidence of vital tumor tissue in the sections of the primary lesion and mediastinal lymph nodes.
Downstaging
By means of the surgical specimens that were obtained,
postoperative tumor stage and pathologic lymph node stage were
established and were compared to the corresponding pretreatment data.
Statistical Analysis
The tumors of regression grades I and IIa and those of grades
IIb and III were grouped together. After calculating the survival
curves according to Kaplan and Meier,7
the median survival
time of both patient groups was compared (log-rank test).8
The effect of downstaging on the overall survival time was checked
using the same methods. Correlations between regression grade and
histologic tumor type, clinical response status, or downstaging
parameters were analyzed (Fishers Exact Test). The relative
importance of factors with significant influence on survival in a
univariate analysis was estimated by multivariate analysis using the
Cox proportional hazards regression model.9
Because of the
limited population, multivariate analysis was carried out in an
explorative approach. Statistical significance was assumed at
p < 0.05.
| Results |
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While 71.4% of squamous cell carcinomas were classified as having regression grades IIb or III, those regression grades were seen in only 58.3% of adenocarcinomas. The remaining tumors (28.6% of squamous cell carcinomas and 41.7% of adenocarcinomas) were of regression grades I or IIa. However, no significant correlation between histologic type and regression grade was demonstrated (p = 0.28 [Fishers Exact Test]).
Morphology of Therapy-Induced Tumor Regression
In 24 patients with tumors of regression grades IIa to III,
different sized target-like foci with central necrosis, narrow foam
cell rim, vascular granulation tissue, and marked peripheral scarring
were demonstrated in the tumor region. In addition, foam cell nests
without central necrosis were present in four resection specimens.
Toward the periphery, the foam cell rims and nests showed transition
into vascular granulation tissue and adjoining cicatrization, sometimes
forming large scarred areas and showing a focally accentuated increase
or condensation of elastic fibers (Fig 2
). In eight specimens (six adenocarcinomas and two squamous cell
carcinomas) of regression grades IIa to III, scarred fibrosis of the
former tumor tissue was the predominant morphologic alteration.
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Correlation of Morphologic Findings to Time-Related Course of
Neoadjuvant Therapy
For the 40 surgically treated patients, the presurgical therapy
period ranged from 97 to 172 days (ie, from the first day of
the first cycle of chemotherapy until the day of surgery), with an
average of 123 days. The time intervals between the last day of
radiochemotherapy and the date of surgery varied from 21 to 96 days,
with 49 days being the average. There was no statistically significant
correlation between the variation of the overall therapy periods or the
variation of the intervals between the last day of radiochemotherapy
and the date of surgery with the different grades of tumor regression
(regression grades I/IIa vs IIb/III [Mann-Whitney U
test]).
The two patients with the longest overall therapy period (172 and 168 days) also showed the longest time interval between radiochemotherapy and surgery (90 and 96 days, respectively). The corresponding resection samples were classified as regression grade IIa with > 10% vital tumor tissue. The morphologic changes seen here could not be separated from those observed in patients with markedly shorter therapy periods.
Presurgical Clinical Response
Based on the response criteria of the SWOG,6
in this
prognostically unfavorable group of 54 patients, efficacy in terms of
response was seen with a response rate of 68.5% and a low 7.4% rate
of progressive disease (Table 1)
. Of the group of 40 surgically treated
patients, 28 showed partial responses, 4 showed complete responses, and
8 showed no change. Among resected tumors in these latter eight
patients, five tumors revealed < 10% vital tumor tissue
(ie, regression grades IIb/III), whereas only three tumors
with > 10% vital tumor tissue were classified as regression grades I
or IIa (Table 2)
. As an illustration, there was a 48-year-old female
patient with progressive disease after chemotherapy and no change after
radiochemotherapy. Macroscopically, the corresponding resection
specimen included a large tumor that was 7 cm in diameter, which, on
histologic examination, proved to be subtotally necrotic with < 10%
vital tumor tissue (regression grade IIb). On the other hand, there was
one tumor with complete clinical response and one tumor with partial
clinical response but that was missing evidence of therapy-induced
tumor regression in the corresponding resection specimens (Table 2)
. In
both cases, the pretherapy tumor stage was confirmed postsurgically.
Both tumors revealed mediastinal infiltration and persistent stage N2
disease. Initially, patients with these tumors presented with a hilar
mass and enlarged mediastinal lymph nodes. After preoperative
induction, the central mass was reduced in one patient to a
paraesophageal mediastinal infiltration, fulfilling the criteria for
partial response, and in the other patient it was reduced to a slight
paramediastinal thickening, fulfilling the criteria for complete
response. Retrospectively, the clinical course of these patients was
highly suspicious of a surrounding inflammatory consolidation that
dissolved with treatment. Altogether, the presurgical response status
after neoadjuvant multimodal therapy was of no predictive value for
assessing the extent of therapy-induced tumor regression in the
corresponding resection specimens (Fishers Exact Test; p = 1.0).
State of Resection
After the end of chemoradiotherapy a total of 40 patients
underwent tumor resection with extensive mediastinal lymph node
sampling. In 34 cases, complete resection (R0 resection) was achieved.
Four patients had microscopic tumor involvement of the resection margin
(R1 resection), and in two patients macroscopic tumor residues were
left intraoperatively (R2 resection).
Survival and Prognostic Impact of Regression Grading
With a median follow-up period of 44 months, the median survival
time for all enrolled patients was 20.4 months, and the 3-year survival
rate amounted to 30%. For patients who underwent resection (n = 40),
the median survival time was 23.0 months, and the 3-year survival rate
amounted to 36%.
Neither patients age (ie, < 60 years vs
60 years),
histologic tumor type (squamous cell carcinoma vs adenocarcinoma), or
disease stage (stage IIIA vs stage IIIB) were revealed as significant
predictors for survival on univariate analysis.
In patients who had undergone resection (n = 40), the morphologic regression grading was applied as described. Patients classified as having regression grades IIb and III (n = 27) showed a significantly longer survival time compared to those who were classified as having regression grades I and IIa (n = 13) (median survival time, 36 vs 14 months, respectively; 3-year survival rate, 52% vs 9%, respectively; p = 0.02 [log-rank test]) (Fig 3 ). Moreover, in patients who had undergone complete tumor resection (n = 34), survival periods could be shown to be significantly longer than in those with incomplete resection or no surgery at all (n = 20). Even in patients who had undergone complete resections, the grade of tumor regression (ie, regression grades IIb/III vs I/IIa) remained a significant predictor for survival (median survival time, not reached vs 23 months, respectively; 3-year survival rate, 56% vs 11%, respectively; p = 0.03 [log-rank test]).
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In univariate analyses, the clinical response to preoperative induction therapy, resection status, and the extent of therapy-induced tumor regression were found to be significant predictors for survival. For patients who had undergone tumor resections (n = 40), a step-by-step multivariate analysis according to the Cox proportional hazards regression model was applied in an explorative approach. Beyond the grade of tumor regression (regression grades I/IIa vs IIb/III; p = 0.007), the resection status (R0 vs non-R0; p = 0.009) was revealed as an independent predictor for survival. This could not be established for clinical response (complete response/partial response vs no change/progressive disease; p = 0.1).
| Discussion |
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No correlation between the time-related course of neoadjuvant therapy and the occurrence of morphologic changes indicating therapy-induced tumor regression or the corresponding regression grade was shown.
Because of the great variability in the time intervals between the last day of radiochemotherapy and the date of surgery (21 to 96 days), one might assume the established regression grade to be not only an effect of therapy-induced tumor regression but also of the differences in tumor cell progression after the end of radiochemotherapy. Nonetheless, there was no correlation between the variation of the preoperative intertreatment interval (ie, the period from the end of radiochemotherapy to surgery) with the different grades of tumor regression. Moreover, according to unpublished data, differences in tumor cell proliferation determined by the Ki67 antigen-labeling index or the extent of apoptosis (terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling technique) did not correlate with different regression grades (regression grade I/IIa vs IIb/III, Mann-Whitney U test).
Statistical evaluation showed that patients with < 10% vital tumor tissue (ie, regression grades IIb/III) had a statistically significant longer median survival time (36 months) than patients with regression grades I or IIa (14 months) (p = 0.02, log-rank test). In an explorative approach, for those patients with tumor resection the extent of tumor regression (regression grades I/IIa vs IIb/III) proved to be a statistically independent prognostic factor.
Bromley and Szur11 reported on 66 cases of resected NSCLC after presurgical radiotherapy. Twenty-nine of the corresponding resection specimens did not show any vital tumor tissue. This finding was not correlated to higher survival rates in the investigated population. Also, Shields et al12 were not able to show survival advantages for patients who had undergone presurgical radiotherapy of lung cancer despite histologically complete tumor regression. However, after the application of neoadjuvant chemotherapy, alone or in combination with radiotherapy, a positive correlation between histologically confirmed complete tumor regression and a favorable prognosis has been discussed.13 14 15 16 17 18 19 Moreover, several trials demonstrated a significant survival advantage according to the extent of histomorphologic response after chemoradiation.3 4 10 20
A high rate of pathologic complete response of 39% was reported by Eberhardt et al21 in the resection specimens of locally advanced NSCLC after preoperative chemoradiotherapy. In contrast to the trials mentioned, after undergoing complete resection, no differences in long-term survival times were found between patients who had a pathologic complete response and those with persistent viable tumors. However, Eberhardt and colleagues21 did not perform a standardized histologic examination of the entire tumor area.
Basically, the determination of complete or predominant tumor regression immediately after the completion of neoadjuvant therapy may offer information on the potential benefits of a particular type of therapy. So, this parameter may be included as an intermediate end point in future neoadjuvant therapy trials involving patients who have stage III NSCLC.3 20 However, complete step-by-step processing of the primary tumor area in the resection specimens and of the resected mediastinal lymph nodes is mandatory. A favorable or unfavorable value of the therapy concept possibly may be determined immediately after completion of the therapy and before reaching a certain follow-up period. Thus, following studies may be started earlier. A standardized classification of tumor regression may also assist in creating an unambiguous description and, subsequently, a better comparability of this parameter in different studies.
A discordance between clinical response to neoadjuvant multimodality therapy and the extent of histomorphologically determined tumor regression has been discussed by several authors.22 23 Additionally, in the present study, no correlation was found between the clinical assessment of the response to neoadjuvant therapy after radiochemotherapy and the grade of tumor regression (p = 1.0, Fishers Exact Test). More than half of the tumors showing no change according to the remission criteria of the SWOG revealed morphologically marked therapy-induced tumor regression with < 10% vital tumor tissue. The predominant cause for this discrepancy is the fact that even in CT scans vital tumor cannot be differentiated from already necrotic tumor tissue or scar formations. After neoadjuvant therapy, tumors of several centimeters may show marked or even complete tumor regression, so that a generous indication for surgery is justified in cases of no change after therapy. The currently used imaging techniques do not allow the reliable determination of therapy success during neoadjuvant therapy.
The question of mediastinal downstaging is of great clinical interest. In contrast to the regression grading system applied here, it could potentially be evaluated prior to surgery by means of mediastinoscopy. The impact of mediastinal downstaging was addressed with a detailed workup in the Massachusetts General Hospital trial by Choi et al,3 who investigated a population of 42 patients with stage IIIA(N2) NSCLC who had undergone preoperative twice-daily radiation therapy and concurrent chemotherapy. In good correlation with our results, they found a lymph node downstaging in 67% of the analyzed tumors (n = 28). Corresponding to our own investigations, Choi et al3 could not show a statistically significant difference in survival between postsurgical stages II (N1) and III (N2), despite different 5-year survival rates of 42% and 18%, respectively. Here, significantly different survival periods were only established comparing postthoracotomy stages 0 and I (N0) vs III (N2) [p = 0.04]. Altogether, the grading of therapy-induced tumor regression, considering both therapy-induced effects in the primary tumor and in lymph node metastases, seems to be a more precise method for predicting the outcome of the disease than the exclusive assessment of mediastinal downstaging.
In conclusion, it has been shown that in resection specimens of stage III NSCLC after neoadjuvant therapy the presence of marked tumor regression with < 10% vital tumor tissue (ie, regression grades IIb/III) is predictive for superior survival times of these patients. The applied regression grading system is an independent prognostic factor in locally advanced lung cancer. The decisive parameters of success in neoadjuvant therapy for patients with locally advanced NSCLC are the achievement of complete tumor resection (R0 status) and total, or at least subtotal, therapy-induced tumor regression.
| Acknowledgements |
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| Footnotes |
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This research was supported by the North Rhine Westfalian Cancer Society, Düsseldorf, Germany.
Received for publication September 18, 2000. Accepted for publication June 14, 2001.
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