纤维支气管镜活检病变组织标本和痰标本Survivin基因的检测对肺癌的诊断价值

目的明确纤维支气管镜(以下简称纤支镜)活检病变组织和痰标本中SurvivinmRNA的检测在肺癌诊断中的意义。方法应用逆转录聚合酶链反应(RT PCR)法检测41例肺癌手术标本癌组织、癌旁组织和9例良性肺疾病病变组织手术标本,80例肺癌和30例良性肺疾病纤支镜活检病变组织标本及所有(160例)患者痰标本SurvivinmRNA表达情况,并与病理组织学、刷检细胞学和痰细胞学检查结果比较。结果肺癌手术切除标本癌组织SurvivinmRNA的阳性率为70.7%(29/41),高于癌旁组织[17.1%(7/41)]和良性肺疾病组织(1/9),差异有统计学意义(χ2值分别为23.97和10.93,P均<0.05),而癌旁组织与肺良性疾病组织相比,差异无统计学意义(χ2=0.20,P>0.05);纤支镜活检肺癌组织标本SurvivinmRNA的阳性率为63.8%(51/80),高于良性肺疾病的13.3%(4/30,χ2值为22.18,P<0.05);肺癌患者癌组织SurvivinmRNA表达与否及表达水平与患者年龄、性别及肿瘤的病理分型、分级、部位及转移情况均无明显相关性(P均>0.05)。肺癌患者痰标本SurvivinmRNA的阳性率是59.5%(72/121),癌细胞的检出率是47.1%(57/121);痰Survivin mRNA检测联合痰细胞学检查诊断肺癌的敏感性为80.2%(97/121),高于单独痰细胞学及单独痰SurvivinmRNA检测的敏感性(P均<0.05)。手术标本、纤支镜活检标     

A comparison of cytology and fluorescence in situ hybridization for the detection of lung cancer in bronchoscopic specimens

STUDY OBJECTIVES: To determine the relative sensitivity and specificity of cytology and fluorescence in situ hybridization (FISH) for the detection of lung cancer in bronchoscopically obtained specimens. DESIGN: Cytology and FISH were performed on brushing and washing specimens obtained from patients undergoing bronchoscopy for suspected lung cancer. FISH utilized the LAVysion probe set (Abbott Molecular; Des Plaines, IL), which contains locus-specific probes to 5p15, 7p12 (EGFR), 8q24 (C-MYC), and a centromeric probe to chromosome 6. SETTING: Single-center, academic, tertiary medical center. PARTICIPANTS: One hundred thirty-seven patients referred for bronchoscopy for suspicion of lung cancer. INTERVENTIONS: Cytology and FISH were performed on bronchoscopic brushings and washings. MEASUREMENTS AND RESULTS: One hundred thirty-seven patients undergoing bronchoscopy had pathology, FISH, and cytology results. FISH and cytology were performed on 123 washing and 78 brushing specimens. Sensitivities of FISH and cytology were 71% and 51% (p = 0.007), respectively, for brushing specimens, and 49% and 44% (p = 0.541) for washing specimens. When FISH and cytology results were combined, sensitivities were 75% and 61%, respectively, for brushing and washing specimens, which was significantly better (p < 0.001) than cytology alone. Specificities of FISH and cytology for patients with negative findings at the time of initial bronchoscopy were 83% and 100% (p = 0.125), respectively, for brushing specimens, and 95% and 100% (p = 0.500) for washing specimens. CONCLUSIONS: These findings show that FISH is significantly more sensitive than conventional cytology for detecting lung cancer in bronchial brushing specimens; when combined with cytology, FISH can improve the diagnostic sensitivity of detecting malignancy in bronchial brushing and washing specimens.     

应用液基细胞技术在肺癌细胞诊断中的意义

目的探讨对支气管镜毛刷标本进行液基薄层细胞学制片技术(LCT)在肺癌细胞诊断中的应用价值。方法收集252例肺癌患者的支气管镜刷检标本,同时进行LCT和直接涂片法检测,比较两种方法的涂片质量及诊断的阳性率。结果 LCT检测的标本切片质量高,LCT诊断肺癌的敏感度为58.33%。直接涂片法诊断肺癌的敏感度为33.19%。LCT的敏感度高于直接涂片法(P0.05)。结论 LCT液基薄层细胞学制片技术在支气管镜刷检细胞学标本制片质量及诊断准确性明显高于传统涂片方法,支气管镜刷检标本的LCT检测可推广应用于临床。     

Quantitative detection of lung cancer cells by fluorescence in situ hybridization: comparison with conventional cytology

STUDY OBJECTIVE: The aim of this study was to clarify whether fluorescence in situ hybridization (FISH) can diagnose lung cancer in various clinical specimens in comparison with conventional cytology. DESIGN: Prospective study. SETTING: University hospital in a metropolitan area. PATIENTS: Fifty consecutive patients with abnormal chest radiography or CT scan findings were enrolled. The patients included 32 men and 18 women, with an average age of 64 years. The final definitive diagnosis was made by histologic examination, as follows: 38 primary lung cancers (24 adenocarcinomas, 8 squamous cell carcinomas, 2 large cell carcinomas, and 4 small cell carcinomas); 1 metastatic renal cell carcinoma; and 11 benign lesions. METHODS: Four types of clinical specimens were analyzed. Cells obtained by transbronchial brushing and transbronchial fine-needle aspiration using a fiberoptic bronchoscope under fluoroscopy, CT scan-guided percutaneous needle biopsy, and bronchial washings. On every examination, duplicate slides were made for analyses of conventional cytology and FISH. RESULTS: Classifications according to conventional cytology were as follows: class I, 4 patients; class II, 15 patients; class IIIa, 3 patients; class IIIb, 5 patients; and class V, 23 patients. A classification higher than class IIIb was considered to be positive for cancer. For cytology, we found no false-positive cases and 11 false-negative cases. The specificity was 100%, and the sensitivity was 71.8%. By FISH, 34 cases showed aberrant copy numbers in either chromosome 3 or 17. We found no false-positive cases and five false-negative cases. The specificity was 100%, and the sensitivity was 87.1%. CONCLUSION: The ability of FISH to detect aneusomic lung cancer cells is superior to conventional cytology for the diagnosis of lung cancer.     

肺癌支气管冲洗液微卫星DNA的检测及意义

目的　探索肺癌支气管冲洗液中微卫星DNA的改变及其在肺癌诊断中的价值。方法　收集肺癌及良性肺病患者支气管冲洗液和外周血 ,提取DNA ,利用聚合酶链反应、变性聚丙烯酰胺凝胺电脉及银染法检测冲洗液中的微卫星DNA改变 ,并与纤维支气管镜活检 ,刷检作比较。结果　肺癌冲洗液中微卫星DNA改变阳性率5 8% ,其中中心型 5 6% ,低于活检及刷检 ;周围型 61% ,高于活检及刷检。良性肺病未发现微卫星DNA改变。结论　肺癌支气管冲洗液微卫星DNA改变的检测阳性率较高 ,特异性好 ,对于肺癌尤其周围型肺癌的早期诊断具有较好的应用价值     

Usefulness of various diagnostic techniques during fiberoptic bronchoscopy for endoscopically visible lung cancer: should cytologic examinations be performed routinely?

BACKGROUND: The question of which combination of procedures gives the best diagnostic yield following fiberoptic bronchoscopy is controversial. OBJECTIVES: To evaluate the value of various diagnostic techniques following fiberoptic bronchoscopy in the diagnosis of endoscopically visible lung cancer. METHODS: The study included 98 patients found to have endobronchially visible tumor during routine daily bronchoscopy. Endobronchial lesions were classified as mass, submucosal lesion and infiltration. Washings, brushings and forceps biopsies were obtained in all subjects. Transbronchial needle aspirations were performed in 67 of 76 cases with mass or submucosal lesions. RESULTS: Bronchoscopy was diagnostic for cancer in 88 (89.8%) of the 98 patients. Forceps biopsy specimens gave positive result in 82.7% of cases, transbronchial needle aspirates in 68.6%, brushings in 68.4%, and washings in 31.6%. Combination of forceps biopsy and brushing cytology yielded a positive result for lung cancer in 87 patients. The addition of brushings increased the diagnostic yield of bronchoscopy from 82.7% to 88.8% (p < 0.05). Collection of washing specimens in addition to forceps biopsy did not increase the yield of forceps biopsy. Transbronchial needle aspiration gave an additional yield of 1%. CONCLUSIONS: Routine cytological examination of bronchial washings does not increase the yield of forceps biopsy specimens. Transbronchial needle aspiration may give an additional positive yield to forceps biopsy. We conclude that a combination of forceps biopsy and brushing is the best strategy in the diagnosis of bronchoscopically visible lung cancer.     

The combination of stricture dilation, endoscopic needle aspiration, and biliary brushings significantly improves diagnostic yield from malignant bile duct strictures.

BACKGROUND: Brush cytology, routinely performed at ERCP to assess malignant-appearing biliary strictures, is limited by relatively low sensitivity and negative predictive value. This study assessed whether the combination of stricture dilation, endoscopic needle aspiration, and biliary brushing improves diagnostic yield. METHODS: In a prospective nonrandomized study, 46 consecutive patients were evaluated with malignant-appearing biliary strictures at ERCP. Twenty-four patients (Group A) underwent standard brush cytology alone and 22 patients (Group B) underwent stricture dilatation to 10F, endoscopic needle aspiration, and subsequent biliary brushing by using the Howell biliary system. The diagnostic yields for both techniques were compared. RESULTS: Of the 46 patients, 34 had proven malignant strictures (14 Group A, 20 Group B). Compared with brushing alone, the combination of stricture dilatation, endoscopic needle aspiration, and subsequent biliary brushing significantly increased both the sensitivity (57% vs. 85%, p < 0.02) and specificity (80% vs. 100%, p < 0.02) of cytology with positive brushings in all patients with pancreatic or gallbladder carcinoma. CONCLUSIONS: The combination of stricture dilation, endoscopic needle aspiration, and biliary brushing significantly improves diagnostic yield for malignant bile duct strictures and may particularly be of benefit for extrinsic strictures caused by pancreatic or gallbladder carcinoma.     

The optimal sequence for bronchial brushing and forceps biopsy in lung cancer diagnosis: a random control study

Background

Optimizing basic techniques in diagnostic bronchoscopy is important for improving medical services in developing countries. In this study, the optimal sequence of bronchial brushing relative to bronchial biopsy for lung cancer diagnosis was evaluated.

Methods

A total of 420 patients with visible endobronchial tumors were prospectively and randomly enrolled in two groups: a pre-biopsy brushing group, receiving two brushings before biopsy; two brushings which performed afterwards; were set as self-control and compared with the pre-biopsy brushings as the intra-group comparison; and a post-biopsy brushing group, only receiving two brushings after biopsy, which were compared with the pre-biopsy brushings as the inter-group comparison. Diagnostic yield of brushing was compared before and after biopsy, and as well as for different tumor pathologies and bronchoscopic morphologies. The occurrence of treated bleeding which defined as bleeding needed further intervention with argon plasma coagulation and/or anti-coagulation drugs in two groups was also compared.

Results

Only patients with a definitive cytological or histological diagnosis of lung cancer based on bronchoscopy or other confirmatory techniques were included. Patients were excluded if they had submucosal lesions, extrinsic compressions, pulmonary metastasis of extrapulmonary malignancies or uncommon non-small cell lung carcinoma (NSCLC). A total of 362 patients who met the inclusion criteria were analyzed. Diagnostic yield for pre-biopsy brushing (49.2%, 88/179) was significantly higher than for post-biopsy brushing within the same pre–biopsy brushing group (31.8%, 57/179) (P=0.007) as the intra-group comparison, and significantly higher than for post-biopsy brushing in the post group (30.6%, 56/183) (P<0.001) as the inter-group comparison. No difference in occurrence of treated bleeding for pre- vs. post-biopsy bronchial brushing was found.

Conclusions

Supplementing bronchoscopic forceps biopsy with brushing improves diagnostic yield in lung cancer. In cases of endobronchial exophytic tumors, pre-biopsy brushing appears to be superior to post-biopsy brushing.     

支气管肺泡灌洗液细胞DNA含量分析在周围型肺癌中的诊断价值

目的探讨支气管肺泡灌洗液细胞DNA含量分析对周围型肺癌的诊断价值。方法采用全自动细胞DNA定量分析系统,对31例周围型肺癌及20例肺良性病变患者的支气管肺泡灌洗液细胞作DNA含量分析,并与纤维支气管镜活检和刷检比较。结果灌洗液细胞DNA含量分析诊断周围型肺癌的敏感性为67．7％,特异性为95．0％,显著高于活检（29．0％）和刷检（32．3％）的阳性率（P均〈0.01）。结论支气管肺泡灌洗液细胞DNA含量分析是诊断周围型肺癌有效的辅助方法。     

Fine-needle aspiration biopsy-RT-PCR expression analysis of prothymosin alpha and parathymosin in thyroid: novel proliferation markers?

Fine-needle aspiration biopsy-based cytology has become an established and reliable diagnostic preoperative test in the evaluation of thyroid nodules. Despite the high specificity and sensitivity of the method, results might be doubtful in a significant number of cases. Genetic analysis of the aspirates by RT-PCR may contribute, in parallel to the cytology report, to a more precise diagnosis. Prothymosin alpha and parathymosin are two homologous chromatin remodeling proteins essential for cell cycle progression and proliferation of either normal or malignant cells. A semi-quantitative RT-PCR assay was developed to determine prothymosin alpha and parathymosin mRNA expression patterns in thyroid follicular cells obtained from the fine-needle aspiration biopsy specimens of patients diagnosed with simple nodular goitre, follicular adenoma, papillary and follicular well-differentiated carcinomas. Prothymosin alpha and parathymosin mRNA levels were found significantly elevated in well-differentiated carcinomas in relation to adenomas (p<0.05) and goitres (p<0.05), an event possibly linked to the proliferation activity of thyroid follicular cells. Further studies are required to establish prothymosin alpha and parathymosin as diagnostic proliferation markers in thyroid cancer, especially in cases of undetermined cellular morphology of follicular origin which reflect the most common cytohistopathological discrepancies.     

Endoscopic Retrograde Wire-Guided Brush Cytology for Diagnosis of patients with Malignant Obstruction of the Bile Duct

A brush was adapted for use over a guide wire to facilitate reliable acquisition of cytological specimens from tight and potentially malignant strictures encountered during ERCP. Cells collected in this manner were assessed for abnormalities indicative of cancer. We have called this technique endoscopic retrograde wire-guided brush cytology (ERWBC). Thirty-nine strictures (24 malignant. 15 benign) in 34 patients were brushed. There were no complications, and all specimens were adequate for evaluation. Sixty percent of patients with cancer were diagnosed by ERWBC. Sensitivity was highest for cholangiocarcinoma (100%), intermediate for pancreatic cancer (60%), and lowest for patients with biliary obstruction due to metastatic disease (22%). I here were no false-positive results (specificity, 100%). The positive and negative predictive values were 100% and 58%, respectively, and accuracy for the test was 72%. Collection of cytological specimens using a brush with a wire guide is effective especially for diagnosis of cholangiocarcinoma. A positive result is sufficient evidence for malignancy, and other invasive diagnostic tests are unnecessary. We recommend ERV\BC for brushing all strictures of unknown cause during LRCP in an effort to make a diagnosis of cancer.     

Application of transbronchial brushing for histological diagnosis of lung cancer

In order to improve the preoperative diagnostic rate of lung cancer, histological examination was performed by transbronchial brushing in 35 cases, and diagnostic contribution of brushing specimen was compared with that of transbronchial forceps biopsy (TBFB). Histological structures were well preserved in the histology section of brushing specimens, especially in cases of small cell lung cancer. The positive rate of brushing histology was 46%, which was the same as that of TBFB. The total histological diagnostic rate was 66% with simultaneous examination of bronchial brushing and TBFB specimens. Consequently, the use of brushing specimens for histologic evaluation made an additional contribution to the correct positive histology diagnostic rate. Brushing histology is indicated for all types of lung cancer, because in most TBFB-negative cases, biopsies were performed from inappropriate sites of tumors or their materials wer crushed by forceps. It was suggested that concomitant application of brushing specimen for histology examination, contributed to more accurate preoperative histology diagnosis for lung cancer.     

Diagnostic value of bronchoalveolar lavage and postbronchoscopic sputum cytology in peripheral lung cancer

Abstract The objective of this study was to evaluate the value of bronchoalveolar lavage (BAL) and postbronchoscopic sputum cytology in diagnosing peripheral lung cancer. We performed a prospective study in 55 patients with lesions on chest radiographs who were suspected of having lung cancer and had non-endoscopically visible lesions on fiberoptic bronchoscopy. The sequence of procedures in all cases was BAL and transbronchial forceps biopsy. The final diagnosis of these patients were primary lung cancer in 30 patients, metatastic lung cancer in five and benign diseases in 20. In the primary lung cancer group, BAL was positive for malignant cells in 14 of the 30 patients (46.7%). In seven (50%) of these patients, the cell type diagnosed by BAL agreed with the final diagnosis. The diagnostic yield of BAL was influenced by the size and segmental location of the lesion. Bronchoalveolar lavage provided a higher diagnostic yield (46.7%) than transbronchial biopsy (16.7%). In five patients with metastatic lung cancer and 20 patients with benign disease, BAL gave negative results in all. Postbronchoscopic sputum cytology was positive in only two of the 26 patients (7.7%) from whom samples could be obtained. Bronchoalveolar lavage cytology proved to be a valuable diagnostic tool in detecting peripheral, primary lung cancer. Postbronchoscopic sputum cytology provided no significant additional information.     

Lung cancer cell type as a determinant of bronchoscopy yield

The accuracy of diagnosis of lung cancer obtained by fiberoptic bronchoscopy utilizing sputum cytology and bronchial biopsy depends on the size, location, and number of biopsy samples taken from the tumor. We have found that the accuracy of diagnosis also depends upon the histologic type of cancer. Fiberoptic bronchoscopy (brushings, washing, and biopsies) was performed and sputum cytology and bronchial tissue was obtained from 51 patients with histologically-proven lung cancer. The bronchial biopsy was more sensitive than the bronchial washing and brushing techniques in detecting primary bronchogenic and metastatic carcinoma. It was positive in ten of ten patients with small cell carcinoma, 12 out of 20 cases of squamous cell carcinoma, three of four cases of adenocarcinoma, and three of four patients with large cell cancer. The bronchial biopsy yield was influenced by the histologic cell type with the highest diagnostic yield being found with small cell carcinoma.     

支气管活检标本的端粒酶活性检测对肺癌的诊断价值

目的：探讨肺癌组织端粒酶活性检测对肺癌的诊断价值。方法采用端粒酶重复序列扩增法检测纤维支气管镜活组织检查的肺癌病变组织（７０例）、肺癌对侧支气管组织（７０例）及非癌性肺疾病支气管组织（２０例）的端粒酶活性,并和病理学及细胞学检查结果进行比较。结果肺癌病变组织端粒酶检出率为８１％,明显高于肺癌对侧支气管组织（１４％）（Ｐ〈０．０１）及非癌性肺疾病支气管组织（１０％）的检出率（Ｐ〈０．０１）;肺癌组织     

Thyroid-stimulating hormone receptor messenger ribonucleic acid measurement in blood as a marker for circulating thyroid cancer cells and its role in the preoperative diagnosis of thyroid cancer

CONTEXT: Thyroid cancer cells express TSH receptor (TSHR) mRNA, and its measurement in the circulation may be useful in the diagnosis/management of differentiated thyroid cancer (DTC). OBJECTIVE: Our objective was to assess the diagnostic value of circulating TSHR mRNA for preoperative detection of DTC in patients with thyroid nodules. PATIENTS: We measured TSHR mRNA levels by RT-PCR in 258 subjects: 51 healthy subjects and 207 patients (thyroid nodules, n = 180; recurrent thyroid cancer, n = 27) with fine-needle aspirations (FNA) and/or thyroid/neck surgery. Eighty-nine patients also had d-1 postoperative levels assessed. OUTCOME MEASURES: TSHR mRNA levels were compared with FNA cytology for cancer detection preoperatively and serum thyroglobulin and/or whole-body 131I scans postoperatively. RESULTS: Based on cytology/pathology, 88 patients had DTC and 119 had benign thyroid disease. The TSHR mRNA levels in cancer patients were significantly higher than in benign disease (P < 0.0001). At a cutoff value of 1.02 ng/microg total RNA, the TSHR mRNA correctly classified 78.7% of patients preoperatively (sensitivity = 72.0%; specificity = 82.5%). Of 131 patients with FNA and surgery, 51 were FNA positive (all cancer), 17 were FNA negative (15 benign, two cancer), and 63 were indeterminate. TSHR mRNA correctly diagnosed DTC in 16 of 24 (67%) and benign disease in 29 of 39 (74%) patients with indeterminate FNA (combined sensitivity = 90%; specificity = 80%). Combining TSHR mRNA and ultrasound features for follicular lesions correctly classified all follicular cancers and could have spared surgery in 31% of these patients with benign disease. TSHR mRNA has a short life in circulation, and normalized levels on postoperative d 1 correlated with disease-free status, whereas elevated levels predicted residual/metastatic disease. CONCLUSIONS: TSHR mRNA measured with FNA enhances the preoperative detection of cancer in patients with thyroid nodules, reducing unnecessary surgeries, and immediate postoperative levels can predict residual/metastatic disease.     

Multitarget fluorescence in situ hybridization elucidates equivocal lung cytology

The category of equivocal respiratory cytology is a common diagnostic dilemma to both cytopathologists and clinicians. Chromosomal alterations are a hallmark of cancer but are rare or absent in benign conditions. The goal of this study was to test the ability of multitarget fluorescence in situ hybridization (FISH) for dissecting equivocal respiratory cytology into reactive and malignant categories. A consecutive series of 54 Papanicolaou-stained cytologic specimens of the lung was analyzed. The Papanicolaou-stained atypical cell groups were photographed, and the exact locations on the specimens were saved using automated stage and relocation software. The specimens were hybridized with a multitarget FISH probe that contains a mixture of fluorescent probes to the centromeric region of chromosome 6 and to the 5p15, 8q24 (site of the MYC gene) and 7p12 (site of the EGFR gene) loci. The hybridized atypical cells were selectively scored after relocation. A final diagnosis was available in 45 patients, revealing lung carcinoma in 55.5% (n = 25), no evidence of malignancy in 37.8% (n = 17), and pulmonary metastasis of another primary carcinoma in 6.7% (n = 3). FISH results were negative in all 17 patients with benign pulmonary disease and positive in 20 of the 25 patients (80%) with lung carcinoma (p < 0.0001). The sensitivity, specificity, and positive and negative predictive values for detection of malignancy were 79%, 100%, 100%, and 74%, respectively. These data suggest that multitarget FISH in conjunction with automated relocation is a powerful approach for the elucidation of equivocal lung cytology.     

老年原发性非小细胞肺癌患者外周血T细胞膜型和可溶性CD28的表达

目的 检测老年原发性非小细胞肺癌(NSCLC)患者外周血T细胞膜型CD28(mCD28)及血清中可溶性CD28(sCD28)的表达,探讨该分子增龄性改变与老年人肺癌发生发展之间的联系.方法 应用四色免疫荧光标记流式细胞术和酶联免疫吸附法对63例老年人NSCLC(老年肺癌组)外周血的mCD28和sCD28进行检测,将其结果 与老年肺良性病变组(老年非癌组35例)、老年健康组30例、青年健康组30例、青年肺良性病变组(青年非癌组20例)及青年肺癌组(20例)进行对比分析,并研究其与老年人肺癌临床病理特征之间的关系. 结果 老年肺癌组外周血mCD28的表达量[(19.27±6.93)%]显著低于其余各组(F=184.25,P<0.01).其血清sCD28含量[(72.00±6.85)μg/L]则显著高于其余各组(F=365.40,P<0.01);老年健康组外周血mCD28的表达量((46.09±7.34)%]明显低于青年健康组和青年非癌组,其血清sCD28的含量[(35.84±5.02)μg/L]则明显高于青年健康组和青年非癌组;老年非癌组[(42.84±5.82)%、(39.38±6.02)μg/L]与老年健康组比较,两者表达差异均无统计学意义;Logistic回归分析显示,增龄、mCD28表达下调、sCD28含量增加均与肺癌的发生有统计学关联(OR值分别为2.432、0.876,1.113);老年肺癌组Ⅲ～Ⅳ期mCD28和sCD28的表达[(16.51±5.64)%、(75.03±5.98)μg/L]与Ⅰ～Ⅱ期表达[(24.41±8.24)%、(66.73±7.52)μg/L]比较,差异均有统计学意义(t值分别为4.497、4.794,均为P<0.01),而不同病理类型之间比较,差异均无统计学意义(F值分别0.609、0.302,均为P0.05). 结论 呈增龄性下调的mCD28和增龄性上调的sCD28,在老年人原发性肺癌的形成和进展过程中可能起重要作用.