Detection of head and neck cancer with Tc-99(m) glutathione: a correlativestudy with tissue glutathione and glutathione S-transferase levels

In this study glutathione (GSH), a natural tripeptide which plays an import ant role in detoxification reactions, protecting cells against damage from xenobiotics, has been labelled with Tc-99(m) for the demonstration of head and neck cancer. Twenty-eight patients (10 females and 18 males) with vario us malignancies of the head and neck were given 740 MBq of Tc-99(m)-GSH int ravenously and single-photon emission computed tomography (SPECT) images we re obtained at 3 h. Semiquantification was performed by drawing regions of interest on three consecutive transaxial slices and tumour to background ra tios were calculated. In addition, GSH and glutathione S-transferase (GST) levels were measured in the tumour samples and in normal tissue which were obtained during surgery. Scintigraphic images showed that there was increas ed uptake in the tumour compared to the normal contralateral side (tumour/n ormal tissue (mean +/- SD)= 1.94+/-0.76). The tissue analyses revealed incr eased levels of GST in tumour tissues, but both GST and GSH levels in tumou r were not statistically different from those in the normal tissue. We conc lude that scintigraphic visualization of head and neck tumours can be attri buted to increased demand for GSH in cancer. Protein binding might account for the prolonged retention of Tc-99(m)-GSH in the malignant tissue. Like o ther peptides, it is accumulated and excreted by the kidneys, which allows clear visualization of the abdomen without interference from gastrointestin al system activity. ((C) 2001 Lippincott Williams & Wilkins).