Quantitative DNA analysis of small renal cortical neoplasms

Independent value of tumor size and DNA ploidy for the prediction of disease progression in patients with organ-confined renal cell carcinoma

BACKGROUND

Greater than 20% of patients with apparently localized renal cell carcinoma (RCC) present with disease progression after surgery. The objective of the current study was to improve the ability of clinicians to predict prognosis in patients with localized RCC.

METHODS

The authors studied 154 patients with organ-confined RCC classified as pT1 to pT2-pN0-M0 who underwent radical nephrectomy. Follow-up ranged from 24-128 months (median, 72 months). Several morphologic parameters of the tumor were considered. DNA content was analyzed by flow cytometry and tumor size was determined from the surgical specimen. A Cox proportional hazards regression model was used to identify significant independent prognostic factors for disease progression.

RESULTS

At 5 and 10 years of follow-up, disease free survival was found to be 87% and 86%, respectively. Univariate analysis revealed that DNA content, Furhman grade, and tumor size had a statistically significant predictive value for disease progression, whereas, with regard to grade, the difference was significant only between patients with Grade 3 tumors and all other patients with Grade 1-2 tumors (P < 0. 0001). Although DNA content was found to correlate with tumor size (P < 0.0001), multivariate analysis showed that these were the only significant independent predictors of disease progression. The sum of DNA content and tumor size therefore was considered to distinguish separate risk groups. For a patient with diploid RCC, the risk of progression increased from 4% if the tumor size was 3 cm to 43% if the tumor size was 10 cm. For a patient with nondiploid RCC, this risk was 32% if the tumor size was 3 cm, increasing to 99% for tumors measuring 10 cm.

CONCLUSIONS

Stratification of organ-confined RCC according to tumor size and DNA content could possibly provide more information that could be useful in the selection of individuals with significantly different risks of disease progression.

Nephron-sparing surgery for renal cell carcinoma--is tumor size a suitable parameter for indication?

OBJECTIVES

Because patients with small renal cell carcinomas (RCC) are being treated by nephron-sparing surgery with increased frequency, a generally accepted parameter giving additional information as to which kind of tumor is suitable for this treatment is urgently required.

METHODS

In a retrospective analysis of 245 patients who underwent radical nephrectomy for RCC, we investigated whether tumor size could provide the necessary information. We analyzed the association of tumor size with pTNM classification, grade, and the findings of the flow cytometric analysis of the DNA content analyzing the DNA index (DI).

RESULTS

Stage pT1 was found in 23 patients (9.4%), pT2 in 100 (40.8%), pT3 in 109 (44.5%), and pT4 in 13 patients (5.3%). Grade 1 was found in 87 patients (35.5%), grade 2 in 120 (49.0%), and grade 3 in 38 patients (15.5%). A low DI was found in 71%, a moderately increased DI in 20%, and a high DI in 9%. Lymph node metastases were detected in 14% and -distant metastases in 22%. Closer examination of the tumors less than 2.5 cm (n = 23) revealed a significantly lower incidence (P <0.001) of infiltration of the renal capsule (n = 0) than in the rest of the group. Positive lymph nodes or distant metastases could not be found in this subgroup. A multifocal appearance of RCC was detected in only 2 (8.7%) of the 23 patients; it was detected in 67 (30.2%) of the 222 patients in the rest of the group. None of the 23 patients had grade 3 tumors (P <0.05). Fifty-two percent of the tumors were grade 1 and 48% grade 2. None of the 23 had a high DI; a moderately increased DI was found in 1 patient and a low DI in 22 of the 23 patients. Detailed examination of the tumors between 2.5 and 4 cm (n = 29) revealed an infiltration of the renal capsule in 11 (38%); lymph node metastases were found in 2 (6.9%) and metastases in 4 (13.8%). A multifocal appearance was found in 4 (13.9%) of the 29 patients; grade 3 tumors were detected in 3 (10.3%) of 29 patients, grade 2 tumors in 12 (41.4%), and grade 1 tumors in 14 (48.3%). In this subgroup, a high DI was found in 14% (not significant). The examination of tumors larger than 4 cm in size revealed worse results in the pTNM classification, grade, and flow cytometric results.

CONCLUSIONS

Only tumors smaller than 2.5 cm should be considered suitable for nephron-sparing surgery in patients eligible for elective surgery. In patients in whom nephron-sparing surgery is imperative, even tumors between 2.5 and 4 cm appear to be suitable. In patients requiring extensive resection, however, the risk of local recurrence seems to be higher because of the higher incidence of multifocality.

Intratumoral heterogeneity of DNA content in renal cell carcinoma and its prognostic significance

BACKGROUND

A multiple sampling study was performed on 124 specimens of renal cell carcinomas to analyze the consistency and reliability of DNA measurements. The authors investigated intratumoral DNA heterogeneity and its role as a adverse prognostic factor for disease progression.

METHODS

DNA content was analyzed by flow cytometry on three different samples of the same tumor. The Cronbach alpha coefficient was used to assess the reliability and a Cox proportional hazards model was used to test the effect of DNA ploidy heterogeneity on time of disease progression.

RESULTS

The agreement among the DNA ploidy samples was high. The number of aneuploid findings increased significantly with the number of samples analyzed. The presence of non-diploid cell populations was a significant adverse predictive value for disease progression. However, the authors were unable to demonstrate that intratumoral heterogeneity DNA content had any influence on the biological behavior of the tumor.

CONCLUSIONS

Determination of DNA ploidy based on single samples may be inaccurate. Spatial variation in DNA ploidy is a feature of renal cell carcinoma; however, its biologic significance remains to be demonstrated.

Clinicopathologic study of 97 cases of small renal cell carcinomas using DNA flow cytometric analyses

The incidence of small renal cell carcinomas (RCC) has increased recently as diagnostic imaging techniques have improved. The indications for partial nephrectomy for small RCC confined to the kidney are still controversial. Ninety-seven small RCC 2.5 cm or smaller, including incidental, occult, and dialysis associated carcinomas obtained at surgery or autopsy were examined. Various clinicopathologic parameters were assessed and survival was analyzed using the Kaplan-Meir method. Seventy-eight cases were incidental carcinomas. Carcinomas caused death in five cases, four of which had initial signs of metastatic disease. Differences in survival between patients with expansive and invasive (intermediate and infiltrating) growth patterns, solid and other structural patterns, clear and other cell types, grade 1 and higher grades of nuclear atypia, and with and without lymph node metastasis were statistically significant. All surgical cases were alive except one who died of another disease. Poor prognostic factors seen in five fatal autopsy cases included invasive growth pattern, solid structural pattern, spindle cells, grade 3 nuclear atypia, and Bellini duct carcinoma. Small RCC may be treated with partial nephrectomy provided they do not show these features, although there is low risk of recurrence or development of de novo cancer.

DNA image cytometric analysis of paraffin-embedded sections of small renal cortical neoplasms

DNA ploidy analysis of neoplasms is most frequently performed by flow cytometry of single nuclear suspensions or image analysis of Feulgen-stained cytologic specimens. To assess the prognostic significance of ploidy in renal adenomas (less than 3 cm in diameter), nuclear DNA content of 21 renal cortical neoplasms was analyzed by image cytometry (CAS 200, Cell Analysis Systems, Inc., Elmhurst, IL) on Feulgen-stained 5 microns fixed embedded tissue sections. Five (36%) of 14 small neoplasms (so-called renal adenomas; (mean diameter, 7.2 mm; range, 2-24 mm) were in the aneuploid range. Four (57%) of seven carcinomas (mean diameter, 6.3 cm; range, 3.5-10 cm) were aneuploid, a frequency not significantly different from that in the adenomas (P = 0.4). Mean DNA index (1.38) for aneuploid adenomas and carcinomas was identical. Diploid renal adenomas (mean diameter, 5.9 mm) were smaller, although not significantly so (P > 0.05), than the aneuploid ones (mean, 9.7 mm). Size of diploid (mean, 6.7 cm) and aneuploid (mean, 6.1 cm) renal carcinomas was similar. Clinical follow-up studies to evaluate utility of DNA ploidy and proliferative activity in prognosis and management of small renal cortical neoplasms are indicated.

Image cytometry: current applications and future trends

Image cytometry has numerous clinical and research applications and is particularly useful in anatomic pathology for the study of malignant lesions. Modern image systems encompass morphometry, densitometry, neural networks, and expert systems. Rapid advances in technology and the development of user-friendly systems have provided pathologists with an alternative to flow cytometry, particularly useful in the evaluation of small or hypocellular specimens. The most common current application of image cytometry is for DNA analysis, followed by quantitation of immunohistochemical staining. Newer uses under active investigation include development of expert systems that may act as diagnostic consultants in the future. Beyond DNA analysis, image cytometry holds great promise for improved tumor classification, for screening and surveillance in high-risk populations, and as a tool to improve diagnostic ability. This article discusses types of image analysis systems, specimen preparation, data acquisition, current applications in specific organ sites, and possible future applications.

Flow cytometric analysis of small renal tumors

Flow cytometric deoxyribonucleic acid (DNA) content analysis was performed on 26 renal tumors 3.0 cm. or less in maximum diameter. We noted DNA aneuploid cell populations in 8 of 25 tumors (32%) evaluable for DNA ploidy status. DNA aneuploid cells comprised 7 to 59% of the cells in those tumors. In comparison, 12 of 25 tumors (48%) larger than 3.0 cm. had aneuploid cell populations. S phase cell populations were significantly increased in the small aneuploid tumors compared with the small diploid tumors (p < 0.001). We believe that these small tumors have the potential to behave aggressively and, therefore, they should be treated no differently than larger renal neoplasms.

Distribution of lymphoid cells in tonsillar compartments in relation to infection and age. A quantitative study using image analysis

The distribution of lymphoid cells in the mantle zone, germinal center, interfollicular area, and subepithelial area of the tonsil was evaluated quantitatively by image analysis in 66 subjects aged 3 to 66 years. The number of Ig-positive cells in the tonsil decreased with advancing years in all compartments. This inverse correlation to age was statistically significant for IgD-, IgM-, and IgG-positive cells. For T-cells, overall change of each T-cell subset with age was smaller than those of Ig-positive cells. An age-related marked decline was seen for CD4-positive cells only in the subepithelial area and for CD8-positive cells only in the interfollicular area. Ki-67-positive cells, cells undergoing active division, were mainly found in the germinal centers and also diminished with advancing years. Patients with frequent episodes of tonsillitis demonstrated a significant increase of IgD-positive cells and IgG-positive cells in interfollicular and subepithelial compartments and a decrease of CD4-positive T-cells in the germinal centers and subepithelial areas. These results suggest that the tonsillar involution with age is immunologically associated in all compartments with the decrease of Ig-positive cells and Ki-67-positive activated cells resulting in a relative increase of T-cell subsets. The method of image analysis provides a novel and unique approach for quantitative immunohistological study of the tonsil.