A simple test, based on toluidine blue (OraTest), appears to be useful in predicting recurrent oral and head and neck cancers as well as clinically occult lesions. Investigators from Johns Hopkins University (Baltimore) used microsatelite analysis to assess loss of heterozygosity (LOH) at three loci associated with increased risk of oral and head and neck cancers in biopsy samples taken from patients with a history of oral or head and neck cancer.
Of the 46 patients examined, 13 had squamous-cell carcinoma, 11 had carcinoma in situ or dysplasia, and 22 had morphologically normal oral biopsies (Clin Cancer Res 2001; 7: 1963-68). In most cases, researchers took two punch biopsy samples, one from an OraTest-positive area and one from an adjacent negative area.
All of the squamous-cell carcinoma and carcinoma in situ patients showed LOH, and 69% of individuals with morphologically normal epithelia also harboured LOH in at least one marker. The most frequent LOH was found on chromosome 9p21.
"Our study shows that OraTest can find both precancerous and cancerous lesions very effectively", says lead researcher David Sidransky. According to this study, 76% of the lesions detected by OraTest were cancerous or precancerous, refuting earlier results that showed a high proportion of false positives with OraTest.
"We recommend this test for patients with a previous history of aerodigestive tract cancer and for heavy smokers and drinkers over the age of 40," adds Sidransky.
"This area of research is very promising and could lead to rapid uncovering of new molecular risk profiles for patients, as well as healthy subjects at risk for cancer", says Vassiliki Papadimitrakopoulou, (Department of Thoracic/Head and Neck Medical Oncology, MD Anderson Cancer Center, Houston). She also points out that OraTest could be used for patients with oral premalignant lesions and those who have undergone curative treatment of head and neck cancer and are at risk for second primary tumour development. However, the results still need to be clinically validated in prospective studies. "I think that this test, if validated, should be used in conjunction with tests for other molecular and clinical markers", comments Papadimitrakopoulou.
OraTest (Zila Inc., Phoenix), has already been approved for sale in several European countries, and is currently the subject of a phase III trial.