A p16 Positive M1 Oral Tongue Cancer Completely Responsive to the EXTREME Regimen: A Case Report

A 42-year-old woman presented to our clinic with tongue pain and dysarthria. She had a smoking history of 22 pack-years and no history of alcohol consumption. A deep ulcer at the left side of the tongue and induration across the whole tongue were observed. The bilateral cervical lymph nodes were palpable. A biopsy from the ulcer revealed squamous cell carcinoma. PET/CT showed sternal bone metastasis resulting in the final diagnosis of left-sided oral tongue cancer (cT4aN2cM1). Systemic chemotherapy treatment involving 6 courses of the EXTREME regimen followed by weekly cetuximab administration was indicated.After the first two courses, diminished tongue pain and improved dysarthria were observed; complete response was obtained after 6 courses. Re-examination of the biopsy specimen showed that the tumor was p16 positive. The p16 protein is a surrogate marker for HPV, but in this case HPV in-situ hybridization was negative. Locoregional or distant failure were not observed during the 5-year follow-up period.The treatment regimen unexpectedly proved successful. It may be beneficial to examine p16 expression in oral tongue cancer to identify patients that are more likely to benefit from the EXTREME treatment regimen.