DNA ploidy analysis of squamous cell carcinomas of the oral and maxillofacial region: clinical and pathologic correlations

Somatic copy number alterations detected by ultra-deep targeted sequencing predict prognosis in oral cavity squamous cell carcinoma

Background

Ultra-deep targeted sequencing (UDT-Seq) has advanced our knowledge on the incidence and functional significance of somatic mutations. However, the utility of UDT-Seq in detecting copy number alterations (CNAs) remains unclear. With the goal of improving molecular prognostication and identifying new therapeutic targets, we designed this study to assess whether UDT-Seq may be useful for detecting CNA in oral cavity squamous cell carcinoma (OSCC).

Methods

We sequenced a panel of clinically actionable cancer mutations in 310 formalin-fixed paraffin-embedded OSCC specimens. A linear model was developed to overcome uneven coverage across target regions and multiple samples. The 5-year rates of secondary primary tumors, local recurrence, neck recurrence, distant metastases, and survival served as the outcome measures. We confirmed the prognostic significance of the CNA signatures in an independent sample of 105 primary OSCC specimens.

Results

The CNA burden across 10 targeted genes was found to predict prognosis in two independent cohorts. FGFR1 and PIK3CAamplifications were associated with prognosis independent of clinical risk factors. Genes exhibiting CNA were clustered in the proteoglycan metabolism, the FOXO signaling, and the PI3K-AKT signaling pathways, for which targeted drugs are already available or currently under development.

Conclusions

UDT-Seq is clinically useful to identify CNA, which significantly improve the prognostic information provided by traditional clinicopathological risk factors in OSCC patients.

Cancer-associated fibroblasts, a parameter of the tumor microenvironment, overcomes carcinoma-associated parameters in the prognosis of patients with mobile tongue cancer

Mobile tongue squamous cell carcinoma (MTSCC) is known for its strong propensity for regional metastasis and poor patient survival despite aggressive treatment, thus calling for new and reliable markers for predicting prognosis and guiding therapeutic management. Towards this end, three classes of markers were investigated: cancer-associated fibroblasts (CAFs; α-SMA positivity) as a representative of the tumor microenvironment, maspin (mammary serine protease inhibitor) as a tumor marker likely to be modulated by factors within the tumor microenvironment, and DNA content and Ki-67 labeling index as inbuilt tumor markers in 128 cases of MTSCC using immunohistochemistry and image cytometry. Of these markers, only CAF density was independently and relatively strongly associated with elevated mortality from MTSCC. The hazard ratio in the CAF-rich type of tumor microenvironment was 4.85 (95% CI 1.41-16.6, versus the CAF-poor) when adjusted by proportional hazards modeling for the center where the patient was managed, gender, tumor stage, presence of neck metastasis and age at diagnosis. CAF density was unrelated to non-MTSSC mortality. Given the strong association between increased CAF density and higher mortality in MTSCC, routine assessment of CAF density for disease course prognosis and inclusion as an integral part of treatment protocols are recommended.

DNA ploidy analysis by image cytometry helps to identify oral epithelial dysplasias with a high risk of malignant progression

Abnormal DNA content (aneuploidy) has been associated with malignant and premalignant epithelial lesions. The presence of aneuploidy in tumours at an early stage and in dysplastic lesions suggests that analysis of DNA content may be a useful marker for determination of prognosis in these lesions. The aim of this study was to use DNA image cytometry to evaluate aneuploidy in oral dysplastic lesions and to determine whether aneuploidy is associated with malignant progression. Forty-two lesions of oral epithelial dysplasias (OED) that had progressed to oral squamous cell carcinoma (OSCC) and 44 lesions that did not progress were analysed for DNA ploidy using image cytometry of nuclear monolayers prepared from paraffin-embedded tissue. Forty-two OSCC that had arisen from the OED cases and five samples of normal oral mucosa samples (NOM) were also examined. Aneuploidy was found in 14/42 (33.3%) of the OED that progressed, but in only 5/44 (11.3%) of OED that did not progress (p=0.01). A total of 19 OED were aneuploid of which 74% showed malignant progression compared to only 42% of the diploid lesions. The sensitivity and specificity of DNA image cytometry to detect cases with high risk of malignant progression was 0.33 and 0.88, respectively. The PPV and NPV were 0.74 and 0.58. We conclude that aneuploid oral dysplastic lesions have a high risk of malignant progression and that DNA image cytometry might help to identify those lesions most at risk.

Evaluation of nuclear morphometry and DNA ploidy status for detection of malignant and premalignant oral lesions: quantitative cytologic assessment and review of methods for cytomorphometric measurements

PURPOSE

Detection of a precancerous or cancerous lesion when small is one of the most important factors to improve 5-year survival rates of oral cancer. Although surgical biopsy is the most definitive method for diagnosing oral lesions, it is impractical to routinely subject large numbers of patients to biopsy. Recently, cytomorphometric assessments improved by advanced computer-assisted image analysis systems have gained importance. This study was established to evaluate the efficacy of nuclear cytomorphometric analysis and DNA ploidy status for the detection of oral malignancies. Methods used for cytomorphometric analysis were also reviewed.

PATIENTS AND METHODS

Oral mucosal smears (n = 44) were obtained from patients (n = 22) presenting with various oral lesions using a cytobrush immediately before biopsy. Cytomorphometric measurements and nuclear Feulgen DNA content analysis were carried out after the Feulgen staining procedure. Smears from the lesion site constituted the study group whereas contralateral healthy mucosal sites served as control.

RESULTS

DNA ploidy analysis revealed 20 diploid (90.9%) and 2 aneuploid DNA patterns (9.1%) sampled from the lateral margin of the tongue and floor of the mouth. When only malignant lesions were considered, aneuploidy rate was 16.7% whereas a diploid pattern was indicated for 83.3% of the sample. With cytomorphometric measurements, a statistically significant difference was shown for nuclear perimeter, area, diameter equivalent to circle, minimum and maximum Feret, intensity, DNA content (c) and DNA index values.

CONCLUSIONS

Cytomorphometric analysis via oral brush biopsy is a valuable adjunct to biopsy for identification of premalignant and early stage cancerous oral lesions as a rapid and minimally invasive procedure with high specificity and sensitivity rates, requiring no topical or local anesthetic.

Comparison of DNA content parameters in paired, fresh tissue pretreatment biopsies and surgical resections from squamous cell carcinoma of the head and neck

OBJECTIVE

Cellular DNA characteristics derived from pretreatment biopsy (PTB) may become important for predicting treatment outcomes in patients with head and neck squamous cell cancer (HNSCC). Whether the PTB adequately represents the whole specimen is of critical importance.

STUDY DESIGN

In a series of >700 HNSCCs, we identified 59 cases in which the PTB and the surgical resection (SR) met the following criteria: PTB and SR were from the same site, and SR was obtained within 5 weeks of PTB with no intervening treatments.

RESULTS

Twenty-nine percent of the PTB specimens were DNA diploid. Only 1 of the 11 subsequent DNA diploid SR was associated with a DNA aneuploid PTB (91% concordance). Of the 48 DNA aneuploid tumors, 3 were associated with DNA diploid PTB (94% concordance). Three other DNA aneuploid SRs were associated with PTB of poor quality.

CONCLUSION

With respect to DNA ploidy, PTB are representative of SR specimens.

Can flow cytometrically determined DNA ploidy and S-phase fraction predict regional metastasis in squamous cell carcinoma of the oral cavity?

BACKGROUND

The value of flow cytometric analysis of DNA ploidy and S-phase fraction (SPF) as an indicator of regional metastasis in oral cancer is currently being debated. Intratumoral heterogeneity makes this problem complex.

METHODS

Intratumoral DNA ploidy heterogeneity and intratumoral SPF variation were examined using multiple specimens from 31 surgically resected specimens taken from patients with oral cancer without preoperative therapy. Flow cytometric analysis of single biopsy specimens from 79 patients with oral cancer was also undertaken to ascertain their value as indicators of regional metastasis.

RESULTS

Forty-five percent (14 of 31) of tumors showed intratumoral ploidy heterogeneity. Intratumoral SPF variation in the 31 tumors ranged from 0.2% to 6.9% (mean, 3.3%). Multivariate analysis showed that a SPF greater than 27% was the most important parameter for predicting regional metastasis.

CONCLUSIONS

DNA ploidy is heterogeneous within a tumor, whereas SPF is relatively stable and can be correlated with regional metastasis in oral cancer.

Surfing prognostic factors in head and neck cancer at the millennium

The ability to reliably predict cancer outcome could tailor therapy to the aggressiveness of the tumour to achieve the best results in terms of loco-regional control, overall survival and quality of life. Retrospective and prospective clinical trials involving large series of patients have validated some predictive clinical and pathological factors, whereas the utility of many other prognostic factors has not been established. This has led to some confusion in clinical practice. In order to clarify the significance, role and cost of these prognostic factors we carried out a Medline search of all papers published between 1993 and 1998 concerning the reliability and cost of markers with prognostic significance, in head and neck squamous cell carcinoma, and assessed the results according to a number of criteria relating to reliability and cost. Regarding reliability we classified prognostic factors into: (1) those with a proven significance based on the fact that they were unanimously reported as having an independent statistical correlation with outcome and prognosis; and (2) those for which results were not unanimous, and which significance is still controversial. Cost analysis showed a substantial difference between validated tests which are of low cost and experimental tests which are expensive. Based on these data regarding both the reliability and cost of each prognostic factor, we propose guidelines for their use in clinical practice in the year 2000.

Oral cancer in the UK: to screen or not to screen

Although oral squamous cell carcinoma accounts for only a small proportion of malignant neoplasms in the UK, oral cancer incidence and mortality rates have been rising in recent years. The natural history of oral cancer is not adequately understood at present and there is very little information about the epidemiology of precancerous lesions in the UK. There are also insufficient data to provide firm evidence that the percentage of cases arising de novo is greater in the UK and the Western world as compared to the Indian subcontinent. Screening for oral cancer by visual examination is simple, inexpensive and causes little discomfort; however, there is no evidence for the effectiveness of screening for oral cancer either in reducing mortality from the disease or in reducing the incidence of invasive disease by detection and treatment of precancerous lesions. There is currently insufficient evidence to recommend population screening for oral cancer in the UK. Measures aimed at primary prevention of the disease may be a more feasible method of disease control at present.