Microsatellite analyses of recurrence or second primary tumor in head and neck cancer

Background: In head and neck squamous cell carcinoma, distinguishing second primary tumours and recurrences may help to orient clinical decisions concerning therapy. Patients and Methods: A panel of eight microsatellite markers was used to analyse the loss of heterozygosity and genomic instability in a selected group of 32 patients experiencing a recurrence after having undergone surgery for oral or oropharyngeal carcinoma, in order to establish the clonality and origin of the recurrence. Results: Twenty-three patients showed genetic changes in primary and/or relapsing tumour DNA: clonally-related patterns were detected in six cases, whereas the different patterns between paired tumours indicated the presence of a second primary tumour in 17 cases. None of the markers was informative in nine cases. Conclusion: Our observations suggest that only a small proportion of patients have primary and secondary tumours developing from a single contiguous altered field (thus indicating a common clonal origin), whereas the metachronous tumour arises in unrelated fields in the majority of cases.