Molecular analysis of synchronous and metachronous tumors of the lung: impact on management and prognosis

Comparison of properties of tests for assessing tumor clonality

SUMMARY

In a recent article Begg et al. (2007, Biometrics 63, 522-530) proposed a statistical test to determine whether or not a diagnosed second primary tumor is biologically independent of the original primary tumor, by comparing patterns of allelic losses at candidate genetic loci. The proposed concordant mutations test is a conditional test, an adaptation of Fisher's exact test, that requires no knowledge of the marginal mutation probabilities. The test was shown to have generally good properties, but is susceptible to anticonservative bias if there is wide variation in mutation probabilities between loci, or if the individual mutation probabilities of the parental alleles for individual patients differ substantially from each other. In this article, a likelihood ratio test is derived in an effort to address these validity issues. This test requires prespecification of the marginal mutation probabilities at each locus, parameters for which some information will typically be available in the literature. In simulations this test is shown to be valid, but to be considerably less efficient than the concordant mutations test for sample sizes (numbers of informative loci) typical of this problem. Much of the efficiency deficit can be recovered, however, by restricting the allelic imbalance parameter estimate to a prespecified range, assuming that this parameter is in the prespecified range.

Clonal divergence in lung cancer development is associated with allelic loss on chromosome 4

Patients who receive curative treatment for lung cancer can develop additional lung tumors that may or may not be related to the original tumor and thus require different clinical management. If a subsequent tumor has a pattern of allele loss, revealed by allelotype analysis, overlapping that of the first tumor, it is believed to be a local recurrence or metastasis. In this case history, we present loss of heterozygosity analyses of the original primary tumor, and two second primary tumors occurring in the ipsilateral and the contra-lateral lungs. The allelotyping suggests that these tumors are all clonally related but concordance is not complete. Our interpretation is that the original primary tumor and the two new primary tumors have developed to full malignancy independently, but are clonally related, possibly via a clone of motile progenitor cells. Deletion mapping of DNA from biopsies of this patient delineated a region in 4p16 that we had previously shown to be lost in the transition from carcinoma in situ to invasive tumor. We identified a minimally deleted region encompassing six genes including two candidate tumor suppressor genes, CRMP1 a lung cancer metastasis-suppressing gene and PPP2R2C a gene for a regulatory subunit of the PP2 complex known to suppress tumorigenesis, particularly viral induced transformation.

Commonly encountered difficulties in pathologic staging of lung cancer

CONTEXT

Lung cancer is the leading cause of cancer mortality worldwide. Despite technological, therapeutic, and scientific advances, most patients present with incurable disease and a poor chance of long-term survival. For those with potentially curable disease, lung cancer staging greatly influences therapeutic decisions. Therefore, surgical pathologists determine many facets of lung cancer patient care.

OBJECTIVE

To present the current lung cancer staging system and examine the importance of mediastinal lymph node sampling, and also to discuss particularly confusing and/or challenging areas in lung cancer staging, including assessment of visceral pleura invasion, bronchial and carinal involvement, and the staging of synchronous carcinomas.

DATA SOURCES

Published current and prior staging manuals from the American Joint Committee on Cancer and the International Union Against Cancer as well as selected articles pertaining to lung cancer staging and diagnosis accessible through PubMed (National Library of Medicine) form the basis of this review.

CONCLUSIONS

Proper lung cancer staging requires more than a superficial appreciation of the staging system. Clinically relevant specimen gross examination and histologic review depend on a thorough understanding of the staging guidelines. Common sense is also required when one is confronted with a tumor specimen that defies easy assignment to the TNM staging system.

The use of molecular assays to establish definitively the clonality of ipsilateral breast tumor recurrences and patterns of in-breast failure in patients with early-stage breast cancer treated with breast-conserving therapy

BACKGROUND

Results from numerous trials have indicated that breast-conserving therapy (BCT) produces outcomes equivalent to those produced by mastectomy in terms of both locoregional control and survival. However, conservative treatment has resulted in the dilemma of how best to address recurrences when they appear in a breast treated previously with radiation therapy. Attempts have been made to characterize ipsilateral breast tumor recurrences (IBTRs) as either true recurrences of the treated malignancy or new primary carcinomas, because cancers that represent new primary tumors may be associated with a more favorable prognosis compared with cancers that represent true recurrences.

METHODS

The authors studied the clonality of IBTRs relative to the initial invasive carcinomas by using a polymerase chain reaction loss-of-heterozygosity molecular comparison assay in 29 patients who received breast-conserving therapy (BCT).

RESULTS

Twenty-two IBTRs (76%) were related clonally to the initial carcinoma, and 7 IBTRs (24%) were clonally different. Clonally related IBTRs were more frequently higher grade (72.2% vs 14.3%; P = .009) and developed sooner after initial treatment (mean time to IBTR, 4.04 years in clonally related IBTRs vs 9.25 years in clonally different IBTRs; P = .002). Six patients subsequently developed distant metastases, and 5 of those patients (83.3%) had clonally related IBTRs. Clinical IBTR classification and molecular clonality assay results differed in 30% of all patients. The proportion of IBTRs that were related clonally at 5 years, 10 years, and 15 years after BCT were 93%, 67%, and 33%, respectively.

CONCLUSIONS

Clinical classifications of IBTRs were unreliable methods for determining clonality in many patients. Molecular clonality assays provided a reliable means of identifying patients who may benefit from aggressive systemic therapy at the time of IBTR and also provided a more accurate assessment of the efficacy of various forms of local therapy.

Synchronous multiple primary lung cancers with different response to gefitinib

Synchronous bronchiolo-alveolar cell carcinoma (BAC) in both lungs and squamous cell carcinoma in left lung were found in a 66-year-old male smoker. After two courses of chemotherapy with gemcitabine and carboplatin, the left lung mass had partially resolved, however, the extent of BAC had been increased. When gefitinib was used as a second-line chemotherapy, the consolidation lesions of BAC was improved while the mass of squamous cell carcinoma was aggravated. The analysis of epidermal growth factor receptor-tyrosine kinase (EGFR-TK) mutations showed that BAC had the deletion, delE746-A750 in exon 19, however, squamous cell carcinoma had no mutations. These synchronous tumors with different location, histology, status of EGFR-TK mutations and response to chemotherapy might be caused by different molecular pathogenesis.

Problems in pathologic staging of lung cancer

CONTEXT

Tumor stage is the most important prognostic and predictive factor for patients with lung cancer, the most lethal neoplasm in the United States. It is used by thoracic surgeons, radiation therapists, and oncologists to determine whether patients with these neoplasms will be treated surgically with curative intent or with palliative radiation therapy and/or chemotherapy.

OBJECTIVE

To review the variety of practical problems that can arise during the assessment of the pathologic stage and other prognostic/predictive factors included in the College of American Pathologist checklist for evaluation of resected lung neoplasms.

DATA SOURCES

Potential practical difficulties that can arise during the pathologic staging of lung cancer patients include the distinction between pT1, pT2, and pT3 lesions based on their location and the presence of visceral pleura and/or parietal pleura invasion; the differential diagnosis between multiple synchronous or metachronous primary lung neoplasms (pT1m) and intrapulmonary metastasis of non-small cell carcinoma of the lung (pT4 or pM1 according to their location); and the role of the recent American Joint Committee on Cancer terminology for the classification of lymph nodes (isolated tumor cells, micrometastases, and metastases).

CONCLUSIONS

The variety of practical problems that can arise during the assessment of important prognostic and predictive features such as resection margin status and evaluation of lymphovascular invasion are reviewed. A brief discussion of the assessment of the effects of neoadjuvant therapy on resected lung neoplasms is also included.

Patterns of allelic loss of synchronous adenocarcinomas of the lung

Distinction of multiple primary lung carcinomas from intrapulmonary metastases using empiric clinical and histopathologic criteria can be difficult. Recent advances have provided several molecular markers that can be used for clonal analysis of separate tumor nodules and enhance tumor staging and subsequent treatment and prognosis. To address this issue, we performed a microdissection-based allelotyping of 20 cases of histologically similar, pathologic stage T4 adenocarcinomas (ADCs). Loss of heterozygosity (LOH) analysis included a panel of 15 polymorphic microsatellite markers located on 1p, 3p, 5q, 9p, 9q, 10q, 17p, and 22q. The tumor size, visceral pleural and angiolymphatic invasion, lymph node status, outcome, and survival were assessed. Allelotypes of 60 cases of solitary primary non-small cell lung carcinomas (NSCLC) (stages I-II) were used to define the percentage of discordant LOH patterns within solitary primary lung carcinoma that would discriminate between survivors and nonsurvivors. These criteria were used in the analysis of pathologic stage T4 ADC. Two groups of stage T4 cases were created: molecularly homogenous (< or = 40% discordances) (14 cases, 70%), and molecularly heterogenous (>40% discordances) (6 cases, 30%). Molecularly homogenous tumors were more frequently associated with visceral pleural invasion (92% vs. 8%) (P = 0.018). Allelotype did not correlate with age, gender, tumor size, tumor differentiation, lymph node status, angiolymphatic invasion, survival, or outcome. Our study showed that discordant and concordant genotypic profiles exist in morphologically similar synchronous ADC of the lung.

Molecular profiling of primary and metastatic neoplasms in the lung using cytologic material obtained by fine-needle aspiration: report of two cases

Two cases are presented in which molecular analyses of cytologic material obtained by fine-needle aspiration were helpful in establishing relationships between morphologically similar neoplasms in the same patient. For appropriate clinical management, it is important to ascertain whether the tumors represent independent primaries or metastases. Alcohol-fixed cytologic material prepared as cell blocks and formalin-fixed paraffin-embedded tissue were microdissected and analyzed for allelic loss of heterozygosity at multiple preselected genetic loci. The first case illustrates a 69-yr-old man with multiple intrapulmonary nodules involving the upper and lower lobes of the left lung. Genomic analysis showed that the neoplasms in the left upper and lower lung lobes were independent primaries, because the loss of heterozygosity (LOH) patterns were substantially different. By contrast, the second case is that of a 58-yr-old man with a right thyroid nodule and multiple pulmonary tumors. LOH analysis confirmed that a sampled pulmonary tumor represented a metastasis from the thyroid primary, as similar LOH patterns involving locus D9S252 were observed on comparison of the thyroid and pulmonary neoplasms. These cases illustrate the practical diagnostic utility of genomic analysis using cytologic material in the assessment of primary and metastatic malignancies.

A Molecular Genetic and Statistical Approach for the Diagnosis of Dual-Site Cancers

BACKGROUND

Concurrent tumors can be synchronous, independently derived, non-metastatic tumors or metastatic tumors. The prognosis and clinical management of patients with these different concurrent tumor types are different.

METHODS

DNA from normal and tumor tissues of 62 patients with synchronous endometrial and ovarian, bilateral ovarian, or endometrial and bilateral ovarian tumors was analyzed for loss of heterozygosity and microsatellite instability using eight polymorphic microsatellite markers at loci frequently deleted in ovarian and/or endometrial cancers. A statistical algorithm was designed to assess the clonal relationship between the tumors.

RESULTS

The original histopathology reports classified 26 (42%) case patients with single primary tumors and related metastatic lesions and 21 (34%) with independent primary tumors; 15 (24%) were unclassified. Genetic data identified 35 (56%) case patients with single primary tumors and related metastatic lesions, 18 (29%) with independent primary tumors, and nine (15%) that could not be typed. Excluding case patients with histopathology reports for which a clonal relationship was uncertain or was not reported, there was 53% concordance between genetic and histopathology diagnoses. Increasing the stringency of the statistical analysis increased the number of uncertain diagnoses but did not affect the proportion of discordant genetic and histologic diagnoses.

CONCLUSIONS

We have developed a rapid and robust combined genetic and statistical method to establish whether multiple tumors from the same patient represent distinct primary tumors or whether they are clonally related and therefore metastatic. For the majority of case patients, histopathology reports and genetic analyses were in agreement and diagnostic confidence was improved. Importantly, in approximately one-fourth of all case patients, genetic and histopathologic analyses suggested alternative diagnoses. The results suggest that genetic analysis has implications for clinical management and can be performed rapidly as a diagnostic test with paraffin-embedded tissues.

Benefits of resection for metachronous lung cancer

OBJECTIVES

The benefits of resection for metachronous lung cancer are not well described. The objective of this study was to evaluate the safety and efficacy of surgical resection for metachronous lung cancers.

METHODS

We reviewed the charts of all patients who underwent a second resection for a metachronous lung cancer from July 1, 1988, to December 31, 2002. Type of resection, operative morbidity, mortality, and survival by stage were analyzed. Survival was determined by using the Kaplan-Meier survival method. All patients were pathologically staged by using the 1997 American Joint Committee on Cancer standards.

RESULTS

Pulmonary resections were performed in 69 patients who had undergone a previous resection. The mean interval between the first and second resection was 2.4 +/- 2.5 years. Seventy-three percent of patients presented with stage I cancers, 9% with stage II cancers, and 17% with stage III cancers. Lobectomy and wedge resection were performed with equal frequency (42% each) for the metachronous cancers. Operative mortality for the second resection was 5.8%. The mean follow-up after the second resection was 37 months. Overall 5-year actuarial survival for the entire group after the second resection was 33.4%.

CONCLUSIONS

Operations for metachronous cancers provided survival that approximated the expected survival for lung cancer. Surgical intervention should be considered as a safe and effective treatment for resectable metachronous lung cancer in patients with adequate physiologic pulmonary reserve.

Second primary tumors following adjuvant therapy of resected stages II and IIIa non-small cell lung cancer

The occurrence of second primary tumors (SPTs) following adjuvant therapy for resected stages II and IIIa non-small cell lung cancer (NSCLC) was investigated. Data regarding SPTs were prospectively collected in all patients accrued to Eastern Cooperative Group Oncology E3590 (a phase III trial of adjuvant therapy in patients with completely resected stages II and IIIa NSCLC). Four hundred eighty-eight patients were accrued to the study, 242 to the RT arm and 246 to the CRT arm. Median follow-up was 73 months. Thirty patients (6.1%) developed 33 SPTs, 20 in the RT arm and ten in the CRT arm. Ten SPTs occurred within the upper aerodigestive tract, six in the RT arm and four in the CRT arm. Twenty-three SPTs occurred in other organs, 17 in the RT arm and six in the CRT arm. Median time to detection of a SPT for those patients randomized to RT and CRT was 43 and 36 months, respectively. The incidence of SPTs was 1.8% per patient-year of follow-up. Excluding skin tumors, the relative risk of death following diagnosis of a SPT for patients randomized to the CRT arm as compared with those randomized to RT alone was 2.26 (95% confidence interval, 0.78-5.58, P=0.12). Patients are at risk for developing a SPT following resection of stages II and IIIa NSCLC. The majority of SPTs occur outside the aerodigestive tract. Following development of a non-skin SPT, the survival difference between patients who had received adjuvant CRT and those treated with adjuvant RT alone was not significant.

Microsatellite analysis of synchronous and metachronous tumors: a tool for double primary tumor and metastasis assessment

Despite well-established histopathological features and the development of immunostaining of human neoplasms, there are a number of cases in which surgical pathologists cannot assure the origin of synchronous and metachronous tumors. In many cases, the classification of these lesions as either two separate primary tumors or as a single primary tumor with a metastasis has significant implications with respect to patient prognosis and recommendations for therapy. To establish the origin of tumors, we assessed tumor cell clonality using PCR-based microsatellite analysis on microdissected archival tissues for loss of heterozygosity (LOH) and microsatellite instability (MSI) in a series of 19 paired synchronous and metachronous tumors from several organs. As a control group, 15 autopsy cases with an unequivocally recognizable primary tumor and associated metastases were also examined. Based on LOH and MSI findings, and using a panel of 4 to 12 (median 7) microsatellite markers, we were able to establish the clonal pattern of microsatellite changes in 17 out of 19 (89%) biopsy cases and thus determine if they were either double primary tumors (41%) or metastases (59%). Of interest, identical or similar pattern of microsatellite abnormalities were detected in 15 primary tumors and corresponding metastasis from autopsies. Our results indicate that microsatellite analysis for LOH and MSI, as an expression of clonality, provides a useful tool to distinguish double primary neoplasms and metastases in synchronous and metachronous tumors.