Patterns of DNA-ploidy in operable colorectal carcinoma: a prospective study of 100 cases

Stage-specific frequency and prognostic significance of aneuploidy in patients with sporadic colorectal cancer--a meta-analysis and current overview

PURPOSE

Aneuploidy has long been suggested as an independent prognostic marker for colorectal cancer (CRC) patients and could thus aid for individualized medicine. However, due to a large spectrum of deviating studies, expert panels do not recommend ploidy assessment. In order to clarify a potential bias of stage-specific frequency of aneuploidy, we now conducted a meta-analysis combined with a systematic review regarding aneuploidy and prognosis.

METHODS

A systematic, web-based search process retrieved 1935 studies published in English between 1990 and 2011. The defined endpoint for the meta-analysis was an increase in aneuploidy frequency between early- (Dukes A, B and UICC I, II; n = 3632 samples) and late-stage (Dukes C, D and UICC III, IV; n = 3440 samples) colorectal carcinomas.

RESULTS

Of 1935 studies initially identified, 17 image (2130 patients) and 20 (7023 patients) flow cytometric studies were analyzed in detail. The meta-analysis (7072 patients) revealed late-stage CRC to be more frequently aneuploid than early-stage CRC (odds ratio 1.51, 95 % CI 1.37-1.67; p = 0.0007). Independent of tumor stage, the overall range of aneuploidy was 39 to 81 % (median 58 %), and altogether, 21 (54.1 %) studies described a significant prognostic impact of aneuploidy for overall, disease-specific, and recurrence-free survival, respectively.

CONCLUSIONS

A substantial number of studies showed a prognostic importance of aneuploidy in CRC. Furthermore, the higher frequency of aneuploidy in late-stage CRC implies an increase in genomic instability with CRC progression, indicating aneuploidy to be also a stage-specific prognostic marker.

Prognostic significance of proliferative activity, DNA-ploidy, p53 and Ki-ras point mutations in colorectal liver metastases

Paired colorectal liver metastases (CLM) and normal tissue samples from a consecutive series of 36 patients were studied prospectively. MIB-1 expression was studied by immunohistochemistry on paraffin-embedded sections. DNA ploidy and S-phase fraction (SPF) measurements were performed by flow cytometry on frozen tissues. Mutations within the p53 (exons 5-8) and c-Ki-ras (codons 12 and 13) genes were detected by PCR single-strand conformation polymorphism analysis followed by sequencing. A high correlation was observed between the MIB-1 LI and SPF value (rho=0.81; P<0.01). Moreover, p53 gene mutations were associated with either high MIB-1 LI and high SPF. In univariate analysis, SPF and MIB-1 levels were related to risk of death. The association between overall survival and DNA-ploidy or p53 mutations did not reach statistical significance, but a slightly better survival was observed for patients either with DNA-diploid tumours or without mutations (P=0.05 and P=0.06, respectively). SPF was shown by multivariate Cox model analysis to be an independent prognostic variable and thus it might be a useful prognostic factor in patients with CLM.

Flow cytometric DNA ploidy and S-phase fraction correlate with histopathologic indicators of tumor behavior in colorectal carcinoma

BACKGROUND

The clinical behavior of colorectal carcinoma is highly variable without reliable predictive biomarkers. Previous reports have shown that flow cytometric DNA analysis may provide valuable prognostic information in these tumors.

PURPOSE AND METHODS

This study evaluates the DNA ploidy and the S-phase fraction (SPF) on frozen samples obtained from 61 patients with colorectal carcinoma by using flow cytometry, and it correlates the data with histopathologic features known to affect disease prognosis. Tumors were classified using the World Health Organization's histologic criteria and were staged according the American Joint Committee on Cancer's classification system. Grade of the neoplasm, vascular invasion, and perineural tumor spread were evaluated in every case.

RESULTS

Fifty-nine percent of tumors were aneuploid and showed statistically significant higher S-phase values than diploid tumors (22.5 vs. 11.2 percent; P < 0.00001). Mean SPF of the whole series was 17.9 (range, 4.2-44.2) percent. A statistically significant association was found between SPF values and histologic grade (P < 0.0016), nodal status (P < 0.0007), distant metastasis (P < 0.0001), tumor stage (P < 0.0001), venous invasion (P < 0.0002), and lymphatic permeation (P < 0.01) but not with perineural growth and infiltration of the neoplasm through the bowel wall (T). DNA ploidy correlated positively with tumor stage (P < 0.03), and the association between aneuploidy and advanced stages of the disease was statistically significant.

CONCLUSIONS

These findings showed that flow cytometric DNA ploidy and SPF, evaluated in fresh samples, are potentially useful parameters to estimate colorectal carcinoma biopathology. Aneuploidy and high replicative neoplastic activity correlated with histopathologic features that are commonly associated with the prognosis of colorectal carcinoma, being SPF-related to disease dissemination and, therefore, an indicator of clinical relevance.

Genetic heterogeneity in sporadic colorectal adenomas

The majority of colorectal cancers develop from adenomatous polyps under the influence of factors that are still poorly understood. Tumourigenesis is generally considered a multistep process in which multiple genetic alterations occur, eventually reflected in abnormalities of the cellular DNA content. Macroscopical features such as tumour size and tumour architecture (tubular, tubulovillous, or villous) are correlated wit the chance of malignancy in the lesion. Grade of dysplasia can be considered an indicator for the level of progression of the adenoma towards invasive carcinoma. These characteristics were correlated with the presence or absence of K-ras mutations and the DNA ploidy in a prospective study performed on 46 large sporadic colorectal adenomas resected by endoscopy. DNA ploidy and K-ras mutations were analysed in two samples taken at distant sites in the adenomas. Aneuploidy was present in 12 adenomas (26 per cent) and K-ras mutations occurred in 26 (57 per cent). A highly significant correlation was found between aneuploidy and adenoma size, architecture, and grade of dysplasia. The presence of K-ras mutations was significantly correlated only with the size of the adenomas. The proportion of adenomas with aneuploidy and/or a K-ras mutation increased when two samples were analysed instead of one. This observation suggests that the prevalence of genetic mutations and of aneuploidy is probably underestimated, as generally only one sample is investigated. No correlation was observed between K-ras mutations and ploidy. This study demonstrates the presence of genetic heterogeneity in colorectal adenomas and supports the notion that K-ras mutation is an early event, while aneuploidy is a late event in the adenoma-carcinoma sequence.

Prognostic factors of colorectal cancer. Results of multivariate analysis of curative resection cases with or without adjuvant chemotherapy

One thousand two hundred fifty-four cases (610 colonic and 644 rectal cancers resected during 2 years from 1984 and followed up for more than 5 years) were entered from 140 institutions in Japan and analyzed by means of Cox's proportional hazards model. The analyzed pathologic variables were the size and depth of invasion, Dukes' stage, venous invasion, lymphatic permeation, and other clinical features, such as the sex and age of the patient and location of the tumor. The extent of dissection, serum carcinoembryonic antigen (CEA) level, and the presence or absence of adjuvant chemotherapy were also analyzed. Adjuvant chemotherapy consisted of three arms for both colonic and rectal cancers. For colonic cancer, arm I was a combination of i.p. (intraportal) and i.v. mitomycin C (MMC) + p.o. 5-fluorouracil (5-FU); arm II was i.v. MMC + p.o. 5-FU; and arm III was surgery only. For rectal cancer, arm IV was a combination of i.a. (inferior mesenteric artery) and i.v. MMC + p.o. 5-FU; arm V was i.v. MMC + p.o. 5-FU; and arm VI was surgery only. As for the factors affecting the disease-free survival of the patient, multivariate analysis disclosed nodal involvement, venous invasion, an elevated CEA level, and the lower part of the rectum. The effect of adjuvant chemotherapy on the patient's survival was proven for rectal cancer but not for colonic cancer. We conclude that these factors should be considered in setting the stage of tumor pre- and postoperatively.

Biologic and clinical correlations among ploidy, cell kinetics, and the tumor-associated glycoprotein-72 tissue expression in colorectal cancer. Preliminary findings

PURPOSE

The aim of this study was to evaluate the possibility of identifying biologically aggressive subgroups of patients, combining several biologic parameters such as the tumor and normal mucosa values from the ploidy, the S-phase cell percentage, and tumor-associated glycoprotein-72 (TAG-72) expression.

METHODS

One hundred five colorectal cancer patients were studied to analyze the possible prognostic role of ploidy and cell kinetics in multiple fresh specimens from the tumor and normal mucosa. Since the presence of TAG-72 in the colonic mucosa has been correlated to neoplastic transformation, the correlations between these parameters and the quantitative tissue expression of the TAG-72 were analyzed in a subgroup of 53 cases.

RESULTS

A significantly lower five-year disease-free survival rate (21.4 percent) was observed in patients with multiploid tumors, when compared with that observed in patients with diploid or single aneuploid tumors (67.5 percent) (P = 0.03). The quantitative tissue TAG-72 expression contributed in identifying a particular patient subgroup (20 percent), characterized by S-phase percentage and TAG-72 values from the normal mucosa that were unexpectedly higher than 12.1 percent and 7.5 U/mg of proteins, respectively. In particular, when the 25 Dukes B patients were analyzed, similar results were observed. In fact, 14 (56 percent) cases showed high tumor cell proliferation and, surprisingly, a high tissue TAG-72 content in the normal mucosa was found in 4 (28.6 percent) of these patients.

CONCLUSIONS

Other than multiploidy, the biologic aggressiveness of colorectal cancer might be successfully assessed introducing the evaluation of new biologic parameters, such as the TAG-72 content and S-phase percentage values of the normal mucosa, suggesting the possibility of further stratifying this patient population.

Application of the crypt-isolation technique to flow-cytometric analysis of DNA content in colorectal neoplasms

BACKGROUND/AIMS

Conventional flow-cytometric analysis of colorectal tumor DNA content includes both tumor and stromal cell DNA. To improve the method, we evaluated the DNA content of purified epithelial cells using the crypt-isolation technique.

METHODS

Normal and neoplastic crypts were isolated from fresh resected colorectum nonenzymatically. Isolated crypts were digested into single nuclei suspensions and examined by flow cytometry (FCM). Internal controls from normal crypts were used to define diploidy. The neoplastic nuclei in the same individual and mixtures of both normal and neoplastic nuclei in various ratios were analyzed.

RESULTS

Tumors having both diploid and aneuploid stemlines were found more frequently than that reported using conventional FCM. Near-diploid DNA stemlines with DNA indices ranging between 0.90 and 1.10 were detectable. The cases of advanced cancer in which the DNA index was between 0.90 and 0.95 were associated significantly with Dukes' stage C.

CONCLUSIONS

This is the first reported analysis of the DNA content of "pure" neoplastic colorectal epithelia using FCM. Multiploid and near-diploid stemlines were more accurately analyzed than that using conventional FCM.

Flow cytometric DNA analysis of hepatic tumours on ultrasound-guided fine-needle aspirates

A study was performed on a nonconsecutive series of 51 patients in order to assess the feasibility, reliability, and usefulness of flow cytometric (FCM) DNA analysis of samples obtained from benign and malignant hepatic tumours by means of ultrasound-guided fine-needle aspiration (UG-FNA). Cytological and often histological confirmation of the nature of the lesion was obtained in all cases from an expert pathologist. For FCM DNA analysis in 32 cases, it was also possible to use samples obtained at surgery from the actual tumours. There were no post UG-FNA complications, either early or late. It was possible to perform FCM DNA analysis on 6/7 (85.7%) of the benign tumour aspirates and all 44 (100%) coming from the malignant tumours. All the benign tumours showed a DNA-diploid pattern, while the DNA content was aneuploid in 91% of the malignant tumours. Apart from one case, the results of the FCM DNA analysis of the samples removed at surgery were the same as those obtained from the aspirates (97%). FCM DNA analysis on UG-FNA samples from hepatic tumours is a fairly simple, reproducible, well-tolerated technique; it does not involve risks if performed by skilled operators and, since it can be easily repeated even on small tumours, it is a suitable method for monitoring hepatic metastases during chemotherapy.