Flow cytometric analysis of the DNA content of adenocarcinoma of the lung, especially for patients with stage 1 disease with long term follow-up

Clonal evolution and therapeutic resistance in solid tumors

Tumors frequently arise as a result of an acquired genomic instability and the subsequent evolution of neoplastic populations with variable genomes. A barrier to the study of the somatic genetics of human solid tumors in vivo is the presence of admixtures of non-neoplastic cells with normal genomes in patient samples. These can obscure the presence of somatic aberrations including mutations, homozygous deletions, and breakpoints in biopsies of interest. Furthermore, clinical samples frequently contain multiple neoplastic populations that cannot be distinguished by morphology. Consequently, it is difficult to determine whether mutations detected in a sample of interest are concurrent in a single clonal population or if they occur in distinct cell populations in the same sample. The advent of targeted therapies increases the selection for preexisting populations. However the asymmetric distribution of therapeutic targets in clonal populations provides a mechanism for the rapid evolution of resistant disease. Thus, there is a need to not only isolate tumor from normal cells, but to also enrich distinct populations of clonal neoplastic cells in order to apply genome technologies to identify clinically relevant genomic aberrations that drive disease in patients in vivo. To address this we have applied single and multiparameter DNA content based flow assays to the study of solid tumors. Our work has identified examples of clonal resistance to effective therapies. This includes androgen withdrawal in advanced prostate cancer. In addition we demonstrate examples of co-existing clonal populations with highly aberrant genomes and ploidies in a wide variety of solid tumors. We propose that clonal analysis of tumors, based on flow cytometry and high resolution genome analyses of purified neoplastic populations, provides a unique approach to the study of therapeutic responses and the evolution of resistance.

Cytofluorimetric Evaluation of DNA Ploidy in Lung Cancer: A Bronchoscopic Study

The study of the biological characteristics of lung cancer is gaining more and more interest both because of their potential role as prognostic indicators and for therapeutic reasons. The DNA content estimated by flow cytometry in surgical samples of non-small cell lung cancer (NSCLC) has already been demonstrated to be correlated with survival in these patients. From July 1990 to February 1992 we analyzed the DNA distribution of bronchoscopic biopsies from 88 patients with lung cancer (18 small cell lung cancer, SCLC, and 68 NSCLC, two unspecified histology). Twenty-eight tumors (34.6%) had a diploid DNA distribution, while 53 were aneuploid (65.4%). A correlation was found between DNA ploidy and survival. Evaluation of the DNA content in bronchoscopic samples in a large series of patients could determine the role of this analysis prior to surgery in NSCLC and its value as a marker with respect to prognosis and response to therapy in SCLC.

Survival among Chinese women with lung cancer in Singapore: a comparison by stage, histology and smoking status

Lung cancer generally carries a poor prognosis and the determinants of survival have been of interest. However, survival estimates in Asian populations are scarce. This study describes survival rates and their determinants in Singapore Chinese women, a primarily non-smoking population. Three hundred and twenty-six Chinese women, diagnosed with primary lung carcinoma in three major hospitals in Singapore between April 1996 and December 1998, were followed up till 31 December 2000. The Kaplan-Meier method was used for survival analysis. Two hundred and eighty (85.7%) died from the disease during follow-up. The median survival time was 0.7 years and the three-year survival was 15.8%. These survival rates are similar to those of Western populations, and they provide a basis for examining trends over time. Age at diagnosis was an independent prognostic factor [adjusted hazard ratio (relative risk) 1.4, 95% confidence intervals (CI) 1.1-1.9 for women above 65 years relative to younger women]. Most (70.5%) tumours were stage III/IV at diagnosis. Three-year survival ranged from 72% among patients with stage I tumours to 7% for stage IV tumours. Overall, there was no survival difference among different histological types in all stages combined. When limited to stages I and II cancers, adenocarcinomas were associated with a better outcome relative to other histological subtypes combined (adjusted relative risk 0.4, 95% CI 0.1-1.0). Smoking was an independent risk factor (adjusted relative risk 1.3, 95% CI 1.0-1.8). Nevertheless, non-smokers comprised 57.4% of this series, highlighting the importance of increased awareness among health professionals and the public that lung cancer is not only a disease of smokers. The high proportion of late-stage tumours in this study and the impact of disease stage on outcome underline the importance of early detection in improving survival of lung cancer.

Aneuploidy and prognosis of non-small-cell lung cancer: a meta-analysis of published data

In lung cancer, DNA content abnormalities have been described as a heterogeneous spectrum of impaired tumour cell DNA histogram patterns. They are merged into the common term of aneuploidy and probably reflect a high genotypic instability. In non-small-cell lung cancer, the negative effect of aneuploidy has been a subject of controversy inasmuch as studies aimed at determining the survival-DNA content relationship have reported conflicting results. We made a meta-analysis of published studies aimed at determining the prognostic effect of aneuploidy in surgically resected non-small-cell lung cancer. 35 trials have been identified in the literature. A comprehensive collection of data has been constructed taking into account the following parameters: quality of specimen, DNA content assessment method, aneuploidy definition, histology and stage grouping, quality of surgical resection and demographic characteristics of the analysed population. Among the 4033 assessable patients, 2626 suffered from non-small-cell lung cancer with aneuploid DNA content (overall frequency of aneuploidy: 0.65; 95% CI: (0.64-0.67)). The DerSimonian and Laird method was used to estimate the size effects and the Peto and Yusuf method was used in order to generate the odds ratios (OR) of reduction in risk of death for patients affected by a nearly diploid (non-aneuploid) non-small-cell lung cancer. Survivals following surgical resection, from 1 to 5 years, were chosen as the end-points of our meta-analysis. Patients suffering from a nearly diploid tumour benefited from a significant reduction in risk of death at 1, 2, 3 and 4 years with respective OR: 0.51, 0.51, 0.45 and 0.67 (P< 10(-4)for each end-point). 5 years after resection, the reduction of death was of lesser magnitude: OR: 0.87 (P = 0.08). The test for overall statistical heterogeneity was conventionally significant (P< 0.01) for all 5 end-points, however. None of the recorded characteristics of the studies could explain this phenomenon precluding a subset analysis. Therefore, the DerSimonian and Laird method was applied inasmuch as this method allows a correction for heterogeneity. This method demonstrated an increase in survival at 1, 2, 3, 4 and 5 years for patients with diploid tumours with respective size effects of 0.11, 0.15, 0.20, 0.20 and 0.21 (value taking into account the correction for heterogeneity;P< 10(-4)for each end-point). Patients who benefit from a surgical resection for non-small-cell lung cancer with aneuploid DNA content prove to have a higher risk of death. This negative prognostic factor decreases the probability of survival by 11% at one year, a negative effect deteriorating up to 21% at 5 years following surgery.

Assessment of DNA content in formalin-fixed, paraffin-embedded tissue of lung cancer by laser scanning cytometer

A new cytometric device, a laser scanning cytometer was developed to overcome the limitations of flow cytometry (FCM) and image analyses. The purpose of this study was to develop a method that allows laser scanning cytometry (LSC) to be used for measuring the cellular DNA content of paraffin-embedded tissues. Paraffin-embedded lung cancer tissue from 30 patients was analyzed by both FCM (p-FCM) and LSC (p-LSC). In addition, touch preparations from fresh frozen tissues were prepared to provide material for LSC (f-LSC). The limits of agreement for the DNA indices (DI) measured by p-LSC and p-FCM were -0.07 to 0.07, indicating that for a given case, these methods would be expected to differ by no more than 0.07. The limits of agreement for comparisons between the other materials and methods were wider and depended upon the size of the measurements. Agreement between f-LSC and p-FCM was good for small DI values, but poor for large values. Agreement between f-LSC and p-LSC was poor for small and large DI values, but good for moderately sized values. Discordancies in DNA ploidy status between different materials and methods may have been caused by either the heterogeneity within tumors, sampling errors or differences in the interpretation of histograms. This method allows a comparison of the results of DNA analysis with histologic findings from hematoxylineosin-stained sections and the prognosis of the patients.

DNA aneuploidy, S-phase fraction and nuclear p53 positivity in non-small cell lung carcinoma

OBJECTIVES

Surgical resection currently offers the best option for managing non-small cell lung carcinoma (NSCLC) but its efficiency is limited by subsequent tumor recurrence. We evaluated whether flow cytometric study and the p53 gene staining pattern may be useful in this respect.

DESIGN AND METHODS

We took biopsy samples of 40 patients with operable NSCLC to study the frequency of aneuploidy, proliferative activity, and alterations in the p53 tumor suppressor gene and compared them with clinicopathological parameters such as age, gender, smoking, histological type, tumor size, and degree of differentiation. To study DNA content, the nuclei were analyzed by flow cytometry using a FACS flow cytometer (Becton-Dickinson) equipped with an argon ion laser, with a propidium iodide excitation of 488 nm. We used the immunohistochemical technique for p53 analysis in samples of paraffin-embedded tissue corresponding to the same patients from whom fresh tissue was taken.

RESULTS

Nuclear p53 staining was detected in 66.7% of the samples; 69.4% of the cases revealed aneuploid DNA histograms and 59% presented with an S phase fraction of more than 12%. Comparison with clinicopathological parameters showed that p53 protein was associated significantly with histological classification (p = 0.04), gender (p = 0.01), and smoking (p = 0.04).

CONCLUSIONS

Immunodetection of p53 overexpression and DNA ploidy in the bronchial epithelium may be a useful tool in any future multifactorial analysis in such tumors for identifying previous lesions that may progress to malignancy.

Histopathologic prognostic factors in resected adenocarcinomas: is nuclear DNA content prognostic?

BACKGROUND

The pathobiological characteristics of lung adenocarcinoma are still unclear. To identify the factors that may affect the survival of patients undergoing pulmonary resections for adenocarcinoma of the lung, univariate and multivariate analyses were performed for 17 variables of the host, histopathology, nuclear DNA content (NDC), and morphometry of nucleus (nuclear area [NA]) of tumor cells.

METHODS

Seventy-two consecutive patients who underwent resection at the National Cancer Center in Tokyo were studied. They consisted of 45 men and 27 women with an average age of 61.7 years (range, 27 to 83 years). For these patients, NDC and NA were prospectively measured by cytofluorometry and morphometry, respectively. For univariate analysis, 17 factors were studied, including age, sex, TNM stage, diameter of the tumor, pleural involvement, degree of differentiation, scar grade, nuclear atypia, mitotic index, histogram pattern of NDC, mean NDC, number of aneuploid stem cell lines, and mean and SD of NA. A multivariate analysis was performed with Cox's regression model for 16 variables.

RESULTS

In the univariate analysis, 12 factors were significantly related to postoperative survival, including TNM stage, diameter, pleural involvement, nuclear atypia, mitotic index, mean NA, mean NDC, number of aneuploid stem cell lines, and the DNA histogram pattern. In the multivariate analysis, M, T, and the histogram pattern of NDC were significantly associated with survival while N showed a strong, but not significant, association.

CONCLUSIONS

Multivariate analysis of histopathologic prognostic factors indicated that the TNM stage, as well as each component independently, still provided the greatest prognostic value in resected adenocarcinomas of the lung. Among other factors, only NDC significantly affected survival. The importance of NDC measurement should be stressed for predicting the survival after surgical resection more accurately and for selecting patients with a higher risk of recurrence.