DNA cytometry of musculoskeletal tumors. A review

Simultaneous paired analysis of numerical chromosomal aberrations and DNA content in osteosarcoma

Relatively little is known about the biologic relevance of numerical chromosomal changes in relation to DNA content in osteosarcoma. In this study, by using a series of human osteosarcoma cell lines, we standardized a method for the assessment, on the same nuclei specimen, of both specific chromosome copy numbers by fluorescence in situ hybridization (FISH) and the DNA content by static cytofluorometry or image cytometry. On the same cell lines, we also evaluated the DNA content by using flow cytometry and the chromosome number distribution by metaphase analysis. Comparison between these different methods showed that DNA ploidy level as determined by FISH or metaphase analysis is frequently lower than the ploidy pattern as defined by cytometric methods. By using comparative genomic hybridization, we were able to demonstrate that these discrepancies were due to the presence of several unbalanced chromosome aberrations, specifically gains and high-level amplifications, which affect the total DNA content with less effect on the total chromosome number. Thus, evaluation of DNA ploidy in osteosarcoma cells is needed for a correct interpretation of FISH or cytogenetic data concerning numerical chromosomal changes. Evaluation of tumor ploidy in a series of clinical samples demonstrated that in high-grade osteosarcoma, flow cytometry sometimes may give false results because of the presence of high proportions of contaminating, nonneoplastic cells that cannot be excluded from the flow cytometric assessment but that do not interfere with the evaluation of DNA ploidy by static cytofluorometry or image cytometry, in which only tumor cells are selected for the analysis. The possibility of using this method to evaluate, on the same nuclei sample, both specific chromosomal aberrations and DNA ploidy may allow a better determination of numerical chromosomal changes that may be relevant for the biologic behavior of osteosarcoma.

Clinical outcome of patients with previously untreated soft tissue sarcomas in relation to tumor grade, DNA ploidy and karyotype

The most important prognostic factor in soft tissue sarcomas (STS) is tumor grade. Since most grading methods are subject to the interpretation of the individual pathologist, there is a need for objective criteria such as DNA ploidy and karyotype, which are of prognostic value in several types of malignancy. We have analyzed the relationships among tumor grade, DNA ploidy, cytogenetic abnormalities and the clinical outcome of 44 previously untreated patients with 12 different histological types of primary STS. The tumors were graded according to the method of Coindre, which resulted in 9 grade I (20%), 18 grade II (41%) and 17 grade III (39%) STS. DNA flow cytometry and chromosomal analysis were performed using standard techniques. After a median follow-up time of 39 (range, 2-124) months, Kaplan-Meier survival analysis was performed. Significant differences in 5-year overall survival were found between patients with grade I or II and grade III STS (p < 0.05). Seventeen STS were aneuploid and 26 were euploid. In 21 of 39 successfully cultured STS an abnormal karyotype was found. There were no significant differences in survival in relation to DNA ploidy or the presence of chromosomal abnormalities. Our results show that grading had higher prognostic value than DNA ploidy or the presence of cytogenetic abnormalities in this heterogeneous group of STS.

Fine needle aspiration in the diagnosis of bone tumors

Fine needle aspiration (FNA) is an important part of the preoperative diagnosis in bone tumors. The diagnosis must be based on clinical, radiologic and morphologic correlation. In palpable lesions, FNA is performed on the most accessible part of the tumor. Deep-seated and/or non-palpable lesions need radiologic guidance. Material from the FNA can be used for additional examinations, i.e. electron microscopy, immunocytochemistry, cytochemistry, DNA-ploidy analysis, chromosomal analysis and molecular genetics. Those examinations are of particular importance in the primary and differential diagnosis of Ewing sarcoma, osteosarcoma and chondrosarcoma. The majority of tumors in FNA aspirates can be classified as primary (benign or malignant) and metastatic tumors. Cellularity, pleomorphism, chromatin pattern, nucleolar structure, mitotic figures and necrosis are parameters of malignancy.

Assessing prognosis for high-grade soft-tissue sarcomas: search for a marker

BACKGROUND

Although improved staging technology, limb-sparing surgery, and adjunctive radiation and chemotherapy have improved the outlook for patients with malignant soft-tissue tumors of the trunk and extremities, it is evident that we cannot predict which patients will develop distant metastases. Although local control is now frequently achieved, most series of high-grade soft-tissue sarcomas carry a mortality rate of > 50%.

METHODS

In a retrospective study of 93 patients with high-grade sarcomas treated between 1986 and 1992 for whom complete studies including size and volume measurements and DNA ploidy determinations as assessed by flow cytometry were available, a search for a marker for increased risk of metastasis or death was performed.

RESULTS

Grade of the lesion, sex, diagnosis, anatomical site, ploidic data (including mean DNA index and presence of an aneuploid peak), and treatment factors (including type of surgery, local recurrence, or radiation protocol) did not correlate with outcome. Age (younger patients did better), size (greatest diameter) and volume, and positive margins at surgery correlated with total survival.

CONCLUSIONS

The results of the study, although negative, point out that using anatomical site, diagnosis, or ploidic analysis offers little toward anticipating outcome, whereas the size of the tumor is important.

Orthopedic soft-tissue tumors. Concepts for the primary care physician

Mesenchymal neoplasia includes an extensive variety of tumors. It is important that the primary care physician understand the different qualities of benign and malignant processes in incidence, pathogenesis, history, physical findings, and diagnostic work-up and, as a result, be able to make the appropriate orthopedic consultation when necessary. It also is important that they understand basic concepts of definitive treatment so that they may educate their patients. Table 2 lists some of the more common benign and malignant soft-tissue tumors. It is by no means an attempt to be inclusive, but rather to serve as an introduction to a vast group of neoplasms.

Cartilaginous tumors: prognostic applications of cytophotometric DNA analysis

BACKGROUND

Traditionally, selection of cancer therapy is based on the assessment of the prognosis of the individual patient. The specific type of tumor and the stage of disease have been the most reliable indicators of prognosis.

METHODS

Image cytometry to determine DNA content was used in conjunction with clinicopathologic parameters and patient survival to investigate 16 cartilaginous tumors. Histopathologic characteristics, cytometric DNA ploidy status, 2c deviation index (2cDI), DNA malignancy grade (DNA-MG), and 5c-exceeding event (5cEE) were used to learn more about the determination of tumor prognosis. Prognosis was analyzed with a maximum follow-up of 148 months.

RESULTS

DNA ploidy status, 2cDI, DNA-MG, and 5cEE are indicators of prognosis. After 148 months of follow-up, patients with aneuploid tumors had a significantly lower overall survival rate compared with those with diploid tumors (P < 0.05). Patients with DNA-MG less than 0.8 or 2cDI less than 1.5 had a significantly longer overall survival rate with respect to the group of patients with a DNA-MG greater than 0.8 or 2cDI greater than 1.5 (P < 0.001). A significant difference was noted in the overall survival rates between patients with tumors with 5cEE less than 3 and 5cEE 3 or greater (P < 0.001).

CONCLUSION

Image cytophotometry DNA ploidy status, 2c deviations index, DNA malignancy grade, and 5c exceeding event were investigated and were found to be of prognostic value for patients with cartilaginous tumors.

DNA and RNA content analysis by flow cytometry in the pathobiologic assessment of bone tumors

Studies of simultaneous DNA and RNA contents by flow cytometry in hematologic and some solid neoplasms have been shown to provide information that may be useful in the pathobiological evaluation of these neoplasms. We contend that similar analysis may be equally valuable in assessing bone tumors. Our data revealed significant statistical differences in DNA ploidy and proliferative fraction between benign and malignant bone neoplasms. Benign tumors manifested predominantly DNA diploidy and low proliferative activity, whereas the majority of malignant tumors were DNA aneuploid and showed high proliferation rate. No significant difference in the RNA content between different histopathologic categories was found. We observed, however, a distinct and consistently high RNA content pattern in giant cell tumors, aneurysmal bone cysts, and chondroblastomas that may be useful in their differential diagnosis. Analysis of different prognostic factors in malignant tumors indicated that histologic grade and DNA content are a significant prognostic factors. Further analysis of malignant tumors showed that a correlation between the proliferative activity and the clinical outcome in the low grade category and between RNA content and patients' survival in osteosarcomas. Our study also showed that preoperative treatment significantly impacted on the extent of the proliferative fraction in malignant tumors. We conclude that DNA/RNA analysis of bone tumor may assist in: (1) the differential diagnosis of certain bone tumors, (2) evaluation of treatment response, and (3) the biological assessment of osteosarcomas.

Development and optimization of tissue preparative methodology for DNA content analysis of soft tissue neoplasms

Data regarding DNA content parameters in soft tissue sarcoma is limited. Development and optimization of tissue specific preparative techniques for DNA flow cytometry was undertaken prior to routine DNA content analysis of soft tissue neoplasms; 154 soft tissue tumors were studied. Dissociation dependent differences in cellular yields, viabilities, maintenance of DNA aneuploid populations, coefficients of variation, and DNA index supported the need for these developmental studies. Fifty-six of eighty-nine patients had DNA aneuploid soft tissue sarcomas. A relationship between DNA aneuploidy and grade was seen in this series with 38% with low grade, 59% with moderate grade, and 69% with high grade tumors demonstrating DNA aneuploid populations (P < 0.005). The mean S-phase fraction for DNA diploid and aneuploid sarcomas was 7.2% and 13.3%, respectively (P < 0.001). When classified by histologic grade of the primary tumor, a greater percentage of metastatic lesions were DNA aneuploid (4 of 7 grade 2 lesions, and 15 of 16 grade 3 lesions). Decreases in cellular yields and rate of DNA aneuploidy were observed in a subgroup of patients with localized high grade sarcoma treated preoperatively, as compared to patients treated with initial surgery. Prospective correlation of DNA content parameters to prognosis and response to cytotoxic therapy are now possible and are ongoing.

Comparative cytogenetic and DNA flow cytometric analysis of 150 bone and soft-tissue tumors

Samples from 48 benign and 102 malignant bone and soft-tissue tumors were analyzed cytogenetically and by DNA flow cytometry. Clonal chromosome abnormalities were found in 82 tumors and normal karyotypes in 68; 61 tumors were DNA-non-diploid and 89 were diploid. The cytogenetically abnormal tumors were used for comparison between the 2 types of investigation; 45 of these tumors were DNA-diploid and 37 were DNA-non-diploid. There was, with few exceptions, good correspondence between the quantitative estimates of genomic changes by the 2 methods, indicating that the cells cytogenetically analyzed from short-term cultures are representative of the in vivo cell populations. Discrepancies were primarily found in cases with indexes above 1.5, in which the DNA index was higher than the chromosome index. The chromosome analysis suggested that skewed stemline (G0/G1) peaks in the diploid region in DNA histograms indicate the presence of cell populations with small net quantitative genomic changes, although not all such populations were detected by DNA flow cytometric analysis. The view that one of the peaks in bimodal stemline DNA histograms with narrow peaks represents a non-diploid cell population was also corroborated. On average, the cell populations giving rise to double stemlines in DNA histograms showed quantitatively larger genomic changes than those that gave rise to broad or skewed diploid G0/G1 peaks. The findings indicate that these histogram profiles are not artifactual but reflect chromosomal changes in the tumor parenchyma.

DNA content prognostic in soft tissue sarcoma. 102 patients followed for 1-10 years

In a prospective study of 102 patients with soft tissue sarcoma, the prognostic importance of DNA content and clinicopathologic features was analyzed. Based on DNA flow cytometry, 37 lesions were diploid (normal DNA content) and 65 were nondiploid (abnormal DNA content). The 5-year metastasis-free survival rate of the whole series was 0.59. The survival rate was 0.77 for patients with diploid tumors and 0.48 for those with nondiploid tumors (P = 0.01). Multivariate analysis identified two independent metastatic risk factors: increasing tumor size and nondiploidy. Unexpectedly, high malignancy grade (III-IV) was not found to be an independent risk factor for metastasis. The risk of metastasis was strongly related to the number of risk factors present. Thus, the 5-year survival for the 76 patients with no or one risk factor was 0.69, as compared with 0.30 for the 26 patients with two risk factors (P less than 0.0001). Our study shows that metastatic disease in soft tissue sarcoma is closely related to nondiploidy. A prognostication model based on DNA content and tumor size was found to discriminate between patients with a good and a poor prognosis after surgical treatment. The model can be used to identify patients who should be excluded from trials with adjuvant chemotherapy.

Proliferative cell response to loosening of total hip replacements: a cytofluorographic cell cycle analysis

Monocyte/macrophages and fibroblasts are the major reactive cells in the periprosthetic connective tissue in a loose totally replaced hip. Monocyte/macrophages are bone-marrow-derived, hematogenous cells, whereas mesenchymal fibroblasts replenish by local proliferation. The cell-cycle-phase frequency distribution therefore reflects the local mitotic fibroblast response to the loose total hip replacement (THR) implant. In 13 patients who underwent revision of a loose THR implant, most of the local cells were in the resting G0/G1 phase (88.1 +/- 6.3%, mean +/- SD), whereas 8.6 +/- 3.7% were in the S phase of the cycle, and 3.4 +/- 2.9% had already reached the G2/M phase. The highest DNA values were recorded in an osteoarthritic patient undergoing revision 4 years after the primary uncemented THR, while the lowest values were observed in a rheumatoid arthritis patient with a loose cemented prosthesis 15 years after the primary operation. The results suggest that the local proliferative fibroblast response in general is uniform and does not seem to depend on the type of prosthesis or the use of cement. The responses in aggressive granulomatous-type loosening and the common type of loosening were similar.