Flow cytometric DNA analysis of squamous cell carcinomas of the oral cavity: correlation with clinical and histopathological features

Insights into the use of DNA content in head and neck squamous cell carcinoma as a method for patient stratification and targeted therapy: Revisiting old concepts and exploring new possibilities

BACKGROUND

This review aimed to emphasize the implications of DNA content in head and neck squamous cell carcinoma (HNSCC), focusing on its predictive value, role in patient stratification, and potential as a therapeutic target for this malignancy.

METHODS

A narrative review of the literature was conducted through electronic database searches.

RESULTS

In conventional HNSCC, aneuploid tumors are associated with increased lymph node metastasis, locoregional recurrences, poor response to radiotherapy and chemotherapy, and worse prognosis. Few studies specifically address the role of DNA content in young HNSCC patients. These studies reveal that young patients exhibit high DNA content abnormalities, suggesting significant genomic instability and potential genetic differences compared to older patients. Regarding HPV and DNA content, no difference was found between HPV-associated and HPV-independent tumors. More research is needed to understand the role of DNA content in histological subtypes, surgical margins, and targeted therapy.

CONCLUSION

This review highlights the findings related to DNA content in HNSCC, suggesting its usefulness in patient stratification and outcome prediction.

Alpha-smooth muscle actin within epithelial islands is predictive of ameloblastic carcinoma

Ameloblastoma is the most common clinically significant odontogenic tumor. It is considered benign but locally invasive and associated with variable clinico-pathological behavior. Ameloblastic carcinoma is a malignant tumor having features of ameloblastoma in addition to cytologic atypia with or without metastasis. It is aggressive and associated with poor prognosis. The aim of this study was to examine which epithelial and stromal markers are predictive of histologically diagnosed ameloblastic carcinoma and can sufficiently differentiate it from solid/multicystic ameloblastoma (SA). We examined immunohistochemically Ki-67, epithelial membrane antigen (EMA), alpha-smooth muscle actin (alpha-SMA), calponin, p63 and DNA content using image (ICM) and flow cytometry (FCM) in three ameloblastic carcinomas and up to 18 SAs. The important findings were that Ki-67 labeling index was significantly higher in ameloblastic carcinoma than SA while EMA, calponin, p63, ICM and FCM did not sufficiently differentiate the two groups of lesions. Expression of alpha-SMA was consistently obtained within the epithelial island cells of ameloblastic carcinoma and not in SA, although the marker was well expressed in the stroma of both lesions. We therefore conclude that the presence of alpha-SMA within the epithelial islands is highly predictive of ameloblastic carcinoma.

DNA ploidy, proliferative capacity and intratumoral heterogeneity in primary and recurrent head and neck squamous cell carcinomas (HNSCC) – Potential implications for clinical management and treatment decisions

Despite new diagnostic and therapeutic strategies (combined radiochemotherapy, EGFR antibody Cetuximab), the prognosis of head and neck squamous cell carcinoma (HNSCC) is still poor and more information regarding prognosis is essential to establish earlier and better treatment options. To elucidate the role of DNA ploidy and cellular proliferation, resected tumors of 48 patients with primary or recurrent HNSCC were analyzed by flow cytometry and in vitro-5-bromodeoxyuridine incorporation (BrdU). The results were compared with histopathological findings such as tumor size, lymph node involvement and tumor differentiation. To assess the influence of intratumoral heterogeneity of these biological parameters, multiple biopsies (>3) were analyzed by flow cytometry and BrdU-incorporation in 12 larger (>4 cm diameter) tumors. BrdU-labeling index (LI%) was significantly higher in aneuploid HNSCC and correlated significantly with poor histologic differentiation of the analyzed tumor tissues (P<0.001). Furthermore, a trend for higher LI% in nodal positive tumors was observed. Aneuploid HNSCC showed significantly more often tissue dedifferentiation (P=0.049) and in most cases an advanced tumor stage, especially in tumors with biclonal cell lines. Lymph node involvement was also seen more often in aneuploid and undifferentiated tumors. As in aneuploid tumors recurrent HNSCC showed in most cases a higher LI% and poor tissue differentiation, but as a result of the small collection of samples there was no correlation between aneuploidy and tumor recurrence. To proof the robustness of the acquired data and to estimate the influence of intratumoral heterogeneity to ploidy and LI% multiple biopsies were analyzed in larger tumors. Using a specific statistical algorithm a secure estimation of ploidy and LI% was possible by a single biopsy in these tumors. These findings indicate aneuploidy and proliferative activity as important findings for malignant progression in HNSCC. An estimation of these biological parameters may be useful for identification of patients with high risk for lymph node involvement or tumor recurrence and pre-treatment can be performed by a single biopsy. As a conclusion, these patients may benefit from more aggressive treatment.

Staging of the neck in patients with head and neck squamous cell cancer: Imaging techniques and biomarkers

Regional metastasis is an important factor in the treatment and prognosis of head and neck cancer patients. Current treatment strategies rely on staging based on the still limited accuracy of imaging techniques to detect regional metastases. If more certainty about the nodal status could be attained, treatment strategies concerning the neck could be better adjusted to the individual patient. The continuing improvement of established imaging techniques and the introduction of new imaging modalities will add to better staging. Moreover, the additional use of biomarkers studied on a protein, RNA or DNA level may provide even better information about the chance of occult nodal metastasis in head and neck cancer patients.

DNA ploidy status as a prognostic marker and predictor of lymph node metastasis in laryngeal carcinoma

In patients with laryngeal carcinoma, nodal metastasis, recurrence after radiotherapy, and prognosis are important factors in clinical decision-making. Parameters such as tumor stage are considered insufficient for predicting these important items. The DNA ploidy status of the tumor may be a useful additional marker. The DNA ploidy status of 38 laryngeal cancers was determined by flow cytometry. Correlations were studied with TNM stage, differentiation, survival rate, relapse risk, recurrence after radiotherapy, and nodal metastasis. A positive correlation of DNA ploidy status with the development of lymph node metastases was found for diploid and peridiploid versus aneuploid tumors (DNA index, <1.4 versus > or = 1.4; p = .007). No correlation was found between ploidy status and recurrence after radiotherapy. The overall survival rate (p = .01), but not the disease-specific survival rate or the relapse risk, showed a correlation with the ploidy status. The DNA ploidy status may be a useful marker for metastatic behavior in head and neck squamous cell carcinoma and may therefore be helpful in decision-making concerning elective treatment of the neck.

Flow cytometric DNA ploidy analysis of oral cancer comparison with histologic grading

It has been reported that DNA content analysis provides prognostic information eliminating the subjective component involved in routine microscopic decision making. In an attempt to establish a relationship between pathological findings and flow cytometric analysis, 36 formalin-fixed, paraffin-embedded tumour tissue samples were prepared according to Hedley's method and analysed by means of an Epics Profile II flow cytometer. DNA aneuploidy was observed in 15 tumours (41%). A statistically significant correlation was identified between DNA index and mitoses, cellular response and degree of differentiation, but not the ploidy status. It was not possible to identify a significant association of sex, age, and site of the tumour to DNA index. We found a strong correlation between histologic malignancy and DNA index; an increase in DNA index as malignancy score increases was noted. It was concluded that DNA index shows a good correlation with the histologic features of oral cancer, being a complement of differentiation and histologic grading analysis. The use of DNA analysis as a complement to pathological studies would help to diminish the subjective component of assessment of head and neck cancers. Ploidy status was not statistically associated with the differentiation of tumours.

The significance of DNA flow cytometry in predicting survival and delayed clinical manifestation of occult lymph node metastasis to the untreated neck in patients with oral squamous cell carcinoma

A total number of 116 clinically neck-negative patients with squamous cell carcinoma of the oral cavity who underwent radical primary tumour surgery without simultaneous neck treatment were entered into this prospective study. The 5 year overall survival rate was 87% for patients with flow cytometrically diploid tumours and 58% for the aneuploid group (P < 0.05). By multivariate survival analysis, tumour stage (P < 0.05) and DNA ploidy (P < 0.05) were significantly associated with the outcome. The cumulative 3 year rate of delayed clinical manifestation of lymph node metastasis to the previously untreated neck was 12.6% for patients with flow cytometrically diploid tumours and 41.3% for the aneuploid group (P < 0.01). By multivariate analysis, the DNA ploidy status of the primary tumour was the only factor among tumour stage, localization and degree of histological differentiation predictive of occult metastasis development (P < 0.05). Also, patients with T1 tumours who frequently are not considered to benefit from elective neck dissection were at high risk of subclinical lymph node involvement if the primary tumours were aneuploid (47%), whereas only 10% of the diploid T1 sample showed occult neck disease. Particularly in patients with less extensive oral carcinomas, DNA aneuploidy is therefore an important decisive factor in elective neck dissection.

Tumor DNA content as a prognostic indicator in squamous cell carcinoma of the oral cavity and tongue base

BACKGROUND

Nuclear deoxyribonucleic acid (DNA) content is a prognostic factor in several tumors, and decisions regarding treatment have been made using this parameter. Nevertheless, there is no agreement in head and neck cancer. The purpose of the present study was to ascertain whether tumor DNA content correlated with prognosis in cases of primary squamous cell carcinoma (SCC) of the oral cavity and tongue base.

METHODS

A retrospective study of formalin-fixed, paraffin-embedded tissue from patients with histologically confirmed SCC of the oral cavity and tongue base was performed using flow cytometry. Tumor DNA content was studied in 109 sets of specimens from previously untreated patients. All of them underwent surgical resection at the University "Hospital de La Princesa" between 1982 and 1992. Clinical parameters (age, sex, site of primary tumor, clinical stage, adjuvant therapy received, and disease-free and overall survival) and histologic parameters (histopathologic stage, tumor differentiation, type of inflammatory infiltration, presence of perineural invasion) were recorded in all cases. An exhaustive statistical analysis was applied.

RESULTS

Only the histograms of 93 patients were adequate for consideration. In flow cytometric analysis, DNA aneuploidy was observed in 51 tumors (55%). The proportion of aneuploid tumors was significantly higher in advanced-stage carcinomas (p < .05), tumors with perineural invasion (p < .05) and in men (p < .05). In the 24 patients with lymph node metastasis, the incidence of aneuploidy was 82% (19 of 24) (p < .05). The rate of metastasis and aneuploidy increased as the degree of differentiation decreased (p < .05 for both). Patients with aneuploid carcinomas in both early and advanced stages had shorter relapse-free and overall survival periods than did the patients with diploid tumors (p < .001 for both). A Cox regression analysis demonstrated that ploidy was the single most important prognostic factor in determining relapse and death (p < .001 for both).

CONCLUSIONS

The results indicate that tumor DNA analysis by flow cytometry appears to be useful as a supplement to clinical and histologic evaluation in predicting the tendency of SCC of the oral cavity and tongue base to metastasize to regional lymph nodes and to predict the outcome of the disease.

Feulgen hydrolysis profiles and acid-labile DNA in oral squamous cell carcinoma

The full Feulgen hydrolysis profiles of healthy and malignant oral epithelial cells were compared by measuring the staining density of nuclei using microdensitometry after varying hydrolysis times. Malignant nuclei contained significantly increased levels of acid-labile DNA. The relative amounts of the rapidly hydrolysable fraction were compared after 5 min hydrolysis for exfoliating epithelial cells from healthy oral mucosa, healing chronic ulcers and squamous cell carcinomas. Although the latter exhibited a wide range of values, analysis of variance showed significant differences (P < 0.05) between healthy control and ulcer groups compared to oral carcinoma. The relative proportion of highly acid-labile DNA in malignant nuclei showed a significant positive correlation with mitotic score (P < 0.01) but no significant correlation with nuclear area. It was concluded that since the susceptibility of DNA to acid hydrolysis probably reflects functional differences in nuclear activity between cells, estimation of the highly acid-labile fraction may have diagnostic and/or prognostic value.