Significance of DNA content abnormalities in small rectal cancers

Ploidy and Proliferation Evaluated by Flow Cytometry. An Overview of Techniques and Impact in Oncology

Flow cytometric methods for the assessment of nuclear and chromosomal DNA content and of cell proliferation (including methods based on pulse-chase of bromodeoxyuridine and on monoclonal antibodies against nuclear oncoproteins and proliferation-associated antigens) are illustrated by examples and analyzed critically. The impact of most of these techniques for the study of human solid tumors, with exception of nuclear DNA content evaluation, appears still limited. In particular, new studies of cell lines and clinical material from human tumors using new proliferation markers and multiparameter flow cytometry are necessary to solve a considerable number of methodologic and scientific problems.

DNA content analysis of colorectal cancer defines a distinct 'microsatellite and chromosome stable' group but does not predict response to radiotherapy

Colorectal cancers (CRC) are thought to have genetic instability in the form of either microsatellite instability (MSI) or chromosomal instability (CIN). Recently, tumours have been described without either MSI or CIN, that is, microsatellite and chromosome stable (MACS) CRCs. We investigated the (i) frequency of the MACS-CRCs and (ii) whether this genotype predicted responsiveness to neoadjuvant chemoradiotherapy. To examine the frequency of MACS-CRCs, DNA content (ploidy) was examined in 89 sporadic microsatellite-stable CRCs using flow cytometry. The tumours were also screened for mutations in KRAS/BRAF/TP53/PIK3CA by QMC-PCR. To examine the value of tumour ploidy in predicting response to chemoradiotherapy, DNA content was tested in a separate group of 62 rectal cancers treated with neoadjuvant chemoradiotherapy. Fifty-one of 89 CRCs (57%) were aneuploid and 38 (43%) were diploid. There was no significant association between mutations in TP53/KRAS/BRAF/PIK3CA and ploidy. Testing of association between mutations revealed only mutual exclusivity of KRAS/BRAF mutation (P < 0.001). Of the 62 rectal cancers treated with neoadjuvant chemoradiotherapy, 22 had responded (Mandard tumour regression grade 1/2) and 40 failed to respond (Grade 3-5). Twenty-five of 62 (40%) tumours were diploid, but there was no association between ploidy and response to therapy. We conclude that MACS-CRCs form a significant proportion of microsatellite-stable CRCs with a mutation profile overlapping that of CRCs with CIN. A diploid genotype does not, however, predict the responsiveness to radiotherapy.

DNA ploidy status and prognosis in colorectal cancer: a meta-analysis of published data

PURPOSE

In colorectal cancer, the negative effect of aneuploidy has been a controversy for more than 20 years. Studies to determine a survival-deoxyribonucleic acid content relationship have conflicting results. A systematic literature search followed by a meta-analysis of published studies addressing prognostic effect of aneuploidy for patients who underwent surgical treatment of colon and rectal cancer was conducted.

METHODS

The main outcome measure was the five-year overall mortality rate after surgical resection. For the selected studies, we estimated this outcome for three subsets of patients through separate meta-analyses: 1) for all patients with colorectal cancer; 2) only between patients with Stage II colon cancer; and 3) only for studies in which follow-up losses were declared. The presence of publication bias was assessed with a funnel plot for asymmetry.

RESULTS

A total of 5,478 patients with colorectal cancer were represented in 32 studies (Group 1), we estimated a reduction in the five-year overall mortality from 43.2 percent for aneuploid tumors to 29.2 percent for diploid tumors (combined relative risk = 1.44; 95 percent confidence interval = 1.34-1.55; P < 0.001). In addition, 357 patients with Stage II colon cancer (Group 2) extracted from three studies had an absolute reduction of 14.3 percent in five-year overall mortality favoring diploid tumors (combined relative risk = 1.93; 95 percent confidence interval = 1.29-2.89; P = 0.001). Lastly, of 14 studies in which follow-up losses were declared (Group 3), 2,221 patients were represented and a 15.7 percent mortality reduction was measured favoring patients with diploid tumors (combined relative risk = 1.44; 95 percent confidence interval = 1.3-1.61; P < 0.001).

CONCLUSIONS

Patients who undergo an aneuploid colorectal cancer surgical resection have a higher risk of death after five years. This finding may ultimately impact survival of patients with node-negative colon cancer through adjuvant therapy.

Chromosomal variations within aneuploid cancer lines

Aneuploid cancers exhibit a wide spectrum of clinical aggressiveness, possibly because of varying chromosome compositions. To test this, karyotypes from the diploid CCD-34Lu fibroblast and the aneuploid A549 and SUIT-2 cancer lines underwent fluorescence in situ hybridization (FISH) and DAPI counterstaining. The number of DAPI-stained and FISH-identified chromosomes, 1-22, X,Y, as well as structural abnormalities, were counted and compared using the chi(2), Mann-Whitney rank sum test and the Levene's equality of variance. Virtually all of the evaluable diploid CCD-34Lu karyotypes had 46 chromosomes with two normal-appearing homologues. The aneuploid chromosome numbers per karyotype were highly variable, averaging 62 and 72 for the A549 and SUIT-2 lines, respectively. However, the A549 chromosome numbers were more narrowly distributed than the SUIT-2 karyotype chromosome numbers. Furthermore, 25% of the A549 chromosomes had structural abnormalities compared to only 7% of the SUIT-2 chromosomes. The chromosomal compositions of the aneuploid A549 and SUIT-2 cancer lines are widely divergent, suggesting that diverse genetic alterations, rather than chance, may govern the chromosome makeups of aneuploid cancers.

Cytogenetics and the surgeon: an invaluable tool in diagnosis, prognosis and counselling of patients with solid tumours

BACKGROUND

Cytogenetic studies have become an important part of tumour characterization. In a minority of tumours cytogenetic and/or molecular studies may be of help for diagnosis, selection of treatment protocols and predicting outcome.

METHODS

This article reviews the literature on solid tumour translocations and established family cancer syndromes. In addition, the potential importance of genetics in management of patients with breast, ovarian and pancreatic carcinoma is reviewed.

RESULTS AND CONCLUSION

Cytogenetic analysis of tumours may help confirm the diagnosis when conventional histology demonstrates no evidence of differentiation along a particular tissue pathway. For patients with well defined cancer syndromes, cytogenetic and molecular analysis offers the prospect of screening to reduce the risk of malignant disease. For many malignancies the underlying genetic anomalies are gradually being elucidated. Further studies designed to demonstrate the significance of these findings can only be undertaken if tumour material is collected and stored in optimal conditions for cytogenetic and/or molecular biological studies.

Pancreatic adenocarcinoma

Pancreatic carcinoma is one of the most enigmatic and aggressive malignant disease facing oncologists. A precocious propensity to spread along peripancreatic neurons and lymphatic channels conspires with the limited activity of standard chemotherapeutic agents and the inability to deliver large doses of radiotherapy to the upper abdomen, leaving radical surgical resection as the primary treatment capable of influencing long-term survival. Theoretically, when the tumor is small and confined to the pancreas, adequate locoregional control is possible by radical resection of the tumor, lymph nodes, peripancreatic neurons, and surrounding soft tissue. Realistically, at the time of initial diagnosis, 50% of patients have distant metastases to the liver or peritoneal surface, and more than 80% of the remaining patients have locally advanced tumors. Fewer than 10% of all patients with a small pancreatic adenocarcinoma confined to the pancreas are candidates for cure by use of radical resection as the sole treatment modality. Given these sobering statistics on the late presentation of this tumor, it is not surprising that, even after radical resection, the overall median survival time is only 18 to 20 months and the overall 5-year survival is approximately 10%. These dismal results led to a call in the early 1970s for abandonment of radical therapy in this disease and for treatment of all patients with palliative care only. These statistics are discouraging, but over the last 10 years a therapeutic renaissance has erupted. This resurgence has been driven by surgeons performing pancreaticoduodenectomy with low perioperative mortality rates and excellent functional results. It has been fueled by the use of adjuvant and neoadjuvant chemoradiotherapy protocols. Improved radiographic imaging techniques such as endoscopic retrograde cholangiopancreatography, helical computed tomography scan, and endoscopic ultrasonography are beginning to show promise in facilitating an earlier diagnosis and in providing highly accurate tumor staging without operation. It is hoped that recent observations on the molecular genetics of pancreatic adenocarcinoma will lead to a better understanding of tumor biology, which in turn should result in a more rational application of new diagnostic and therapeutic strategies. Effective percutaneous, endoscopic, and laparoscopic techniques have been developed concomitant with the recent advances in radiographic and endoscopic imaging. These minimally invasive options can now provide meaningful, long-lasting palliation and improved quality of life for the large number of patients with unresectable or metastatic disease who have no other treatment options. The therapeutic nihilism so pervasive in previous decades has no place in the contemporary treatment of patients with pancreatic adenocarcinoma. True long-term survival seems possible for a growing proportion of patients, and minimally invasive, effective palliation is achievable in the vast majority of patients. It is only through aggressive recruitment of patients for treatment, application of novel diagnostic and therapeutic protocols, and further laboratory investigation into the biology of pancreatic cancer that the momentum of the last decade toward improved outcome and quality of life can be sustained.

Nuclear DNA content and pathology in radically treated pancreatic carcinoma. The prognostic significance of DNA ploidy, histology and nuclear grade

BACKGROUND

Nuclear DNA content and pathology are considered to be prognostically relevant in several solid tumors, but controversial findings have emerged in pancreatic carcinoma (PC). Histopathology and DNA ploidy were each correlated with survival in radically treated PC to ascertain the hierarchy of their prognostic significance.

METHODS

DNA ploidy was assessed by flow cytometry (FC) in neoplastic tissue samples from 60 patients with PC who were followed until death. Representative neoplastic areas were obtained by microdissection from archival paraffin embedded material (excluding any carcinoma with a coefficient of variation of the G0/G1 peak higher than 8%). Histologic data and FC patterns were related to prognostic behavior using univariate multivariate statistical analysis.

RESULTS

Aneuploid cancers were detected in 39 of 60 patients. Univariate analysis showed that histologic grade, nuclear grade, and ploidy were significantly related to prognosis. On multivariate analysis, only histologic grade and DNA ploidy (diploid vs. aneuploid) were significant with significant interaction.

CONCLUSIONS

The prognostic value of pathology and ploidy was demonstrated in patients treated radically for PC. As in other tumors characterized by a short survival, the clinical usefulness of any prognostic parameters is somewhat limited. However, the significant relationship between prognosis and DNA ploidy might be of interest in a cost-benefit analysis for selecting patients in whom an attempt at radical surgical treatment or adjunctive chemotherapy may be justified.

Familial pancreatic cancer and the genetics of pancreatic cancer

In our current understanding of pancreatic carcinoma, these neoplasms can arise either sporadically or in familial clusters. Extensive chromosome abnormalities are frequent, as is loss of heterozygosity at loci known to contain the tumor suppressor genes DCC, p53, and MTS1. Although the genetic examination of all pancreatic cancers is important, the examination of familial cases is especially useful in that these allow the identification of uniform genetic alterations that are inherited through the germ line. Much additional work needs to be done before the genetic basis of pancreatic cancer is completely understood. Although our knowledge is limited, it is clear that genetic analyses can be used to establish the prognosis for a patient with pancreatic cancer and, it is hoped, will someday be used in the management, treatment, and detection of pancreatic cancer.

Prognostic profile in rectal cancer

PURPOSE

The purpose of this article was to review the prognostic factors of significance in rectal cancer.

METHODS

This is a retrospective review of various reports and an examination of our data.

RESULTS

Current imaging techniques with endorectal ultrasound, magnetic resonance imaging with a rectal probe, and possibly tagged monoclonal antibodies allow for presurgical assessment of the invasion of the rectal wall and detection of lymph node involvement.

CONCLUSIONS

Tumor penetration of the rectal wall and lymph node metastases are the most important prognostic indicators in rectal cancer and predict local and distant recurrences. When lymph node metastases occur, they are more common in small lymph nodes (< 5 mm). Patients with lymph node metastases always need to be considered for multimodality therapy. Tumors larger than or equal to T3 or with associated lymph node metastases should not be treated with sphincter-saving surgical procedures alone.

Prognostic value of DNA analysis in colorectal carcinoma

BACKGROUND

Reported experiences regarding the prognostic significance of DNA content in colorectal carcinoma have been a matter of controversy.

METHODS

DNA analysis with image cytometry was performed in 137 patients with colorectal cancer. Only patients who had resection without tumor residual and who did not die postoperatively as a consequence of the operation were entered in the study. At the time of DNA analysis, neither the histomorphologic data nor the relapse-free survival time of the patients were known.

RESULTS

In this investigation the DNA content of tumor cells had no univariate or multivariate influence on the relapse-free survival time. The prognosis was dependent on the tumor localization, depth of tumor infiltration, lymph node metastasis, and grade.

CONCLUSIONS

DNA content provides no additional prognostic information in colorectal carcinoma.

A comparison of flow cytometric and absorption cytometric DNA values as prognostic indicators for pancreatic carcinoma

BACKGROUND

The DNA content of 30 adenocarcinomas of the head of the pancreas was measured by flow and absorption cytometric analysis.

METHODS

Each of the patients in this study had curative pancreatoduodenectomy. The absorption cytometric measurements were done in a research laboratory, and the flow cytometric measurements were performed in a commercial laboratory. The DNA measurements were done on nuclei disaggregated from pancreatic cancer tissue blocks without the examiner knowing whether the patient had survived.

RESULTS

Twenty-one of the 30 cancers were found to be aneuploid by absorption cytometric analysis, whereas only 1 of the 30 cancers was aneuploid by flow cytometric analysis. This difference was statistically significant (P < 0.001).

CONCLUSIONS

Univariate and multivariate analyses showed that the absorption cytometric DNA measurements were stronger prognostic determinants for patient survival than were the flow cytometric DNA measurements, indicating that some caution may be warranted in the interpretation of commercially obtained DNA distributions of pancreatic carcinomas.

Surgical treatment of tumors of the distal rectum with sphincter preservation

One hundred one patients with villous adenoma or invasive carcinoma of the distal rectum treated with local excision or coloanal anastomosis were studied. Twenty-three (45%) of the 51 patients with villous adenomas had transanal excision, another 23 (45%) had a posterior proctotomy, and five (10%) had a coloanal anastomosis. Only two patients with a villous adenoma developed a recurrence requiring repeat local excision. Fifteen (30%) of the 50 patients with invasive cancer were treated by transanal excision. All had tumors confined to the submucosa or superficial muscularis. Eighteen (85%) of 21 patients having posterior proctotomy also had tumors with similar depth of invasion. Six (43%) of the 14 patients having coloanal anastomosis had Dukes' B tumors, six (43%) were Dukes' C, and another two (14%) underwent palliative resection. The overall actuarial 5-year survival was 77%. Only four patients treated by transanal excision or posterior proctotomy died of metastatic disease. In the coloanal group, two of 12 patients undergoing curative resection died of recurrent cancer, and another has a pelvic recurrence. Villous adenomas of the distal rectum and selected carcinomas may be treated with local excision and coloanal anastomosis with preservation of sphincter function with good results.

Colorectal carcinoma associated with ulcerative colitis: a study of prognostic indicators

Fifty-two patients with ulcerative colitis and colorectal cancer undergoing colectomy at the Mount Sinai Hospital between 1973 and 1988 were studied retrospectively to determine the correlation of age, sex, duration of colitis, tumor location, number of cancers, tumor differentiation, colloid content, presence of signet ring cells, Dukes' classification, and DNA ploidy with survival. The mean age was 45 years, with a mean duration of colitis of 21 years. Five patients (10%) had Dukes' A lesions, 17 (33%) had Dukes' B lesions, 17 (33%) had Dukes' C lesions, and 13 (25%) had distant metastases. Thirty patients (58%) had well- or moderately differentiated tumors, whereas tumors were poorly differentiated in 22 (42%). Twenty-eight patients (54%) had colloid tumors, and, in 14 (27%), signet ring cells were present. Thirty-one patients (60%) had nondiploid tumors. Actuarial analysis revealed that the 5-year survival rate was significantly worse for patients with nondiploid tumors (76% versus 32%). When stratified by stage, only patients with Dukes' C lesions showed a significant difference in survival for diploid versus nondiploid tumors. Multivariate analysis showed that the Dukes' classification was the best prognostic indicator, followed by tumor differentiation and DNA ploidy. Tumor location, colloid content, number of cancers, duration of disease, age, and sex did not correlate with the prognosis.

Pancreatic cancer cell DNA content correlates with long-term survival after pancreatoduodenectomy

The DNA content of 47 adenocarcinomas arising in the head of the pancreas from patients who had undergone successful pancreatoduodenectomy was measured. The DNA measurements of each tumor were made without knowledge of the clinical course by absorption cytometry performed on Feulgen-stained nuclei that had been disaggregated from pancreatic cancer tissue blocks. Forty-seven evaluable DNA distributions were obtained from specimens taken between 1975 and 1988. Of the 47 tumors, 19 (40%) were diploid and 28 (60%) were aneuploid cancers. The 19 patients with diploid cancers had a median survival time of 25 months. Median survival of the 28 patients with aneuploid cancers was 10.5 months. This difference was statistically significant (p = 0.003). A multivariate life table regression analysis demonstrated that the ploidy and proliferative index as determined by absorption cytometry were independent prognostic factors, as strong as or stronger than the number of positive nodes and tumor size. Thus cellular DNA content appears to be one of the most important predictors of survival in patients with adenocarcinoma of the head of the pancreas who have successfully undergone a pancreaticoduodenectomy.

DNA ploidy of colorectal cancer and synchronous polyps in polyposis coli

Sixteen patients with polyposis coli and cancer were studied retrospectively to determine the incidence of DNA ploidy abnormalities in the tumors and synchronous polyps. Six patients (37 percent) had nondiploid tumors. Nondiploid tumors were more likely to be advanced and had a significantly worse prognosis (17 percent vs. 76 percent 5-year survival; P less than 0.01). Only 4 of 20 polyps studied were nondiploid. There was no association between tumor and polyp ploidy. All nondiploid polyps were found in patients with synchronous diploid cancers. Patients with nondiploid polyps were more likely to be older and have more advanced tumors than those with diploid polyps. DNA ploidy abnormalities seem to occur with the same frequency in polyposis coli as in the nonpolyposis population, and tumor ploidy correlates with prognosis.

Multiple primary colorectal adenocarcinomas: cytometric DNA ploidy patterns and histopathologic features

The nuclear DNA distribution pattern was studied by means of image cytometry in 18 patients with synchronous and 7 patients with metachronous colorectal adenocarcinomas. About 80 percent of a total number of 53 carcinomas were found to consist of neoplastic cells where the nuclear DNA distribution pattern was of the aneuploid type. In 19 of the 25 patients, all carcinomas in the individual colon had identical nuclear DNA distribution patterns. Aneuploid tumors tended to appear more frequently in the sigmoid colon and the rectum than in the right colon. Carcinomas associated with an adenoma were more common in the rectum and in Dukes' A carcinomas. The results of cytometric assessments of the nuclear DNA ploidy pattern of the neoplastic cells in colorectal carcinomas have previously been found to be an independent prognostic variable. From the observations made in the present study, it is concluded that the cytometric DNA ploidy pattern of multiple primary colorectal carcinomas corresponds to that found in single carcinomas. The similarity between the two groups of cancer patients is also supported by conformity between histopathologic features and prognosis.

Heterogeneity in ploidy and S-phase fraction in colorectal adenocarcinomas

The heterogeneity in the DNA content was analysed in multiple biopsies from the surgical specimens in 77 cases of colonic and 46 cases of rectal adenocarcinomas. Frozen and unfixed tumour tissue was analysed with the flow cytometric technique. A total of 78/123 (63%) of all tumours displayed aneuploid stemlines in one or more pieces of tumour tissue; 45 were homogeneously aneuploid and 33 were heterogeneous, presenting both aneuploid and near-diploid samples. The remaining 45 tumours were homogeneously near-diploid. The heterogeneity in ploidy tended to be slightly higher if ten as compared with four samples from each tumour were analysed. Ploidy correlated to localization in the bowel and gender, but not to age, histopathological tumour stage, tumour differentiation or to the resectability rate for cure. The mean value of the S-phase fraction was 17% (range 7-31%) in the near-diploid and 14% (range 8-20%) in the aneuploid tumours. The range of the intratumoural variation was small for the DNA index (at most 5%) and high for the S-phase fraction (19% for near-diploid and 24% for aneuploid tumour pieces). Neither the mean value nor the heterogeneity in the DNA index and in the S-phase fraction displayed any correlation with the studied characteristics. In conclusion, the ploidy and the S-phase fraction varied considerably both within and between the tumours. As a consequence, multiple sampling is mandatory for a correct classification of colorectal adenocarcinomas based on the DNA content.

Prognostic factors in colorectal cancer: current status and new trends

The clinical, laboratory, and pathologic data of 361 patients who had curative resections for colorectal cancers were collected and analyzed in a multiple stepwise regression model. In univariate analysis, among clinical factors, bowel obstruction and emergency surgery showed the most significant prognostic value (P = 0.002, P = 0.004, respectively). Vegetating growth, Astler-Coller stage of tumor, intramural spread, lymph node involvement, and synchronous liver metastases resulted in the pathologic variable significantly affecting the prognosis (P = 0.006, P less than 0.001, P = 0.036, P less than 0.001, P less than 0.001, respectively). In the multivariate analysis, stage was the predictive factor with the highest hazard ratio in conjunction with bowel obstruction (P less than 0.0001 in both cases). Processing data excluding stage ("multiparametric factor" itself), hepatic metastases, lymph node involvement, bowel obstruction, and intramural spread appeared as independent predictors of survival (P less than 0.0001, P less than 0.0001, P = 0.0004, P = 0.0316, respectively). Other variables, as biologic and molecular factors, should be more widely tested in order to assess their impact on prognosis.