"Oral premalignant lesions that stained with toluidine blue consistently contained loss of chromosomal genetic information," Rosin said. In patients with dye-stained lesions, Rosin and colleagues found a strong association with loss of genetic information, termed loss of heterozygosity (LOH), on one or more chromosomes.

"Patients with positively stained tissue had a higher incidence of LOH at multiple sites, including regions on chromosome arms 3p or 9p or both as well as on parts of other chromosomes" Rosin said. Rosin's Cancer Research article reports results from the initial phase of a long term study that followed 100 patients for 44 months. By the completion of the longitudinal study, Rosin and colleagues will monitor 400 patients.

The current report links the staining of cells with toluidine blue in mouth tissue to the higher risk of patients likely to develop squamous cell carcinomas. When biopsied, lesions that stained blue most often showed microscopic abnormal tissue development dysplasia that is associated with cancer risk.

The Rosin team then established that the dye-stained lesions had characteristic molecular alterations that are linked to higher risk for oral cancers -- even when the dye stained tissue is at an early stage, when dysplasia is minimal. Cells with molecular changes took up the blue dye before the lesion acquired extensive dysplasia. The findings are among the first steps in designing and implementing an imaging screening program that dentists and oral hygiene professionals can use to make first-line decisions about early stage biopsies and referrals for anti-cancer related care.

More than 300,000 people worldwide will be diagnosed with oral cancer this year. In the United States, 30,000 people will develop oral cancers. The five-year survival rate for oral cancer remains between 40 and 50 percent--a statistic that hasn't changed over the
'"/>

Contact: Russell Vanderboom, Ph.D.
vanderboom@aacr.org
215-440-9300
American Association for Cancer Research
1-Sep-2005