A group of molecular markers has been identified that can help clinicians determine which patients with low-grade oral premalignant lesions are at high risk for progression to oral cancer, according to data from the Oral Cancer Prediction Longitudinal Study published in Cancer Prevention Research (August 21, 2012).
"The results of our study should help to build awareness that not everyone with a low-grade oral premalignant lesion will progress to cancer," said Miriam Rosin, PhD, director of the Oral Cancer Prevention Program at the British Columbia (BC) Cancer Agency, in a press release issued by the American Association of Cancer Research, which publishes the journal. "However, they should also begin to give clinicians a better idea of which patients need closer follow-up."
In 2000, Rosin and colleagues used samples of oral premalignant lesions in which progression to cancer was known to have subsequently occurred to develop a method for grouping patients into low- or high-risk categories based on differences in their DNA.
In their current population-based study, the researchers confirmed that this approach was able to correctly categorize patients as less or more likely to progress to cancer. They analyzed samples from 296 patients with mild or moderate oral dysplasia identified and followed over years by the BC Oral Biopsy Service, which receives biopsies from dentists and ear, nose, and throat surgeons across the province. Patients classified as high-risk had an almost 23-fold increased risk for progression.
Next, the researchers added two additional DNA molecular risk markers related to loss of heterozygosity to the analysis in an attempt to better differentiate patients' risks. They used the disease samples from the prospective study and categorized patients into low-, intermediate-, and high-risk groups.
"Compared with the low-risk group, intermediate-risk patients had an 11-fold increased risk for progression and the high-risk group had a 52-fold increase in risk for progression," Rosin said.
Of patients categorized as low-risk, only 3.1% had disease that progressed to cancer within five years. In contrast, intermediate-risk patients had a 16.3% five-year progression rate and high-risk patients had a 63.1% five-year progression rate.
"That means that two out of every three high-risk cases are progressing," Rosin said. "Identifying which early lesions are more likely to progress may give clinicians a chance to intervene in high-risk cases and may help to prevent unnecessary treatment in low-risk cases."
