Salivary proteomics of oral squamous cell carcinoma and oral potentially malignant disorders

A new study on the oral squamous cell carcinoma in Proteomics, and I think about the old problem of understanding the difference between head-and-neck squamous cell carcinoma (HNSCC) and oral squamous cell carcinoma (OSCC). I understand the difference now, but it still troubles me that when you say HNSCC, you can compare cancer of the tongue with cancer of the buccal mucosa, or worse, with pharyngeal or laryngeal cancers. Talk about apples and oranges..

Thankfully, in this study, they used oral squamous cell carcinoma. They compared salivary proteomes of healthy individuals (controls) with that of potentially malignant oral disorders (erythroplakia, submucous fibrosis and others) and oral squamous cell carcinoma using a label free method (spectral counting, of course!!). The instrument of choice was a LTQ-Orbitrap (They don't say which one!!) mass spectrometer. They identified over a thousand proteins (with > 2 peptides) and found 33 proteins to be differentially expressed. RETN was selected and validated in a larger cohort using ELISA. They finally suggest that this protein could serve as a potential biomarker for prognosis.