Mutated p53 as a molecular marker for the diagnosis of head and neck cancer

Abstract

In total, 10-30% of patients with head and neck squamous cell carcinoma (HNSCC) develop local recurrences despite seemingly adequate tumour resection. This may result from minimal residual cancer (MRC): small numbers of tumour cells left behind in the surgical margins, undetectable by routine histopathology. In recent studies, p53 mutations have been considered as selective and sensitive DNA markers of cancer cells. There are two potential problems in using mutated-p53 DNA as a marker. Firstly, p53 mutations occur early in progression and might therefore detect unresected precursor lesions besides tumour cells. Secondly, DNA is a very stable biomolecule that might lead to false-positive results. These two potential problems have been evaluated in this study. Fifty patients with a radical tumour resection were included, of whom 30 showed a p53 mutation in the primary tumour. Histopathologically tumour-free surgical margins were quantitatively analysed for mutated p53 by molecular diagnosis (plaque assay) and subsequent (immuno)histopathology. p53 mutated DNA was detected in the surgical margins of 19/30 patients. Immunohistochemistry confirmed the presence of small tumour foci in 2/19 mutated p53-positive cases. In 7/19 cases, the tumour-specific p53 mutation was found in unresected dysplastic mucosal precursor lesions. Moreover, in a number of cases small p53-immunostained patches were detected, but the mutations found were never tumour-related. By screening contralateral exfoliated cells and plaque assays on RNA it was shown that detection of mutated-p53 DNA is prone to false-positive results. In conclusion, using p53 mutations as a marker, both MRC and unresected mutated p53-positive mucosal precursor lesions are detected within surgical margins. Molecular assessment of surgical margins using p53 mutations enables the selection of HNSCC patients at high risk for tumour recurrence, but tumour RNA seems at present to be a more specific biomolecule for analysis than tumour DNA.

Revisit of Field Cancerization in Squamous Cell Carcinoma of Upper Aerodigestive Tract: Better Risk Assessment with Epigenetic Markers

“…Mutations of p53 or p53 oncoprotein are relatively late events in carcinogenesis (42,43), so, despite their biological plausibility as cancer predictors, they are insufficient for risk assessments for SCC in the UADT. Because aberrant DNA methylation usually precedes neoplastic transformation, qualitative studies have suggested that the presence of methylated genes may increase in a sequence from normal mucosa to precursor lesions to SCC (44)(45)(46).…”

Molecular characterization of p16-immunopositive but HPV DNA-negative oropharyngeal carcinomas

“…The mutational status of TP53 in the tumors was determined by direct DNA sequencing essentially as previously described. 24 …”

Prognostic value of cyclin D1 expression in tumor-free surgical margins in head and neck squamous cell carcinomas

“…Alterations in p53 have commonly been found in HNSCCs, but its influence on prognosis remains controversial. In recent reports, p53 mutations, detected by molecular assays such as DNA sequencing, LigAmp assay, and real-time PCR, were considered a useful prognostic factor [9][10][11][12]. However, we previously reported that the IHC assay of p53 was not useful in predicting the prognoses of patients undergoing chemoradiation therapy [13].…”