Radiation treatment decreases transforming growth factor alpha expression in squamous carcinoma of the tongue.

Ionizing radiation (XRT) is often used to treat squamous cell carcinoma of the tongue (SCCT) but little is known of its genetic effects on surviving cancer cells. The effect of XRT on p53, epidermal growth factor receptor (EGFR), and transforming growth factor alpha (TGF alpha) tumor marker expression was evaluated using immunohistochemical analysis in 79 patients with SCCT. Sixty-six patients received no radiation, while 13 received XRT before surgery. Radiation did not influence EGFR or p53 expression. TGF alpha expression, however, was significantly decreased in radiated tumors (15% versus 43%, P = 0.04). These data suggest that XRT either decreases the expression of TGF alpha in SCCT (suggesting a genetic alteration in surviving cancer cells), or does not kill cancer cells with decreased TGF alpha expression. In the latter case, diminished TGF alpha expression may serve as a marker of radioresistance.