An annual trip to the gynecologist for a Pap smear to check for cervical cancer has become a standard regimen for millions of women. But the test is far from perfect, missing up to half of all early stage signs of cervical dysplasia.
Imalux (Cleveland) is in the process of refining an Optical Coherence Tomography (OCT) system that would allow physicians to more precisely differentiate grades of pre-invasive cervical dysplasia prior to biopsy, providing the opportunity for earlier treatment.
"Cervical dysplasia is currently diagnosed in three steps," Nancy Tresser, MD, Imalux vice president and chief medical officer, told Diagnostics & Imaging Week. "We do a Pap smear and then if it's abnormal, you have colposcopy and then a biopsy. If the biopsy shows early cancer or invasive cancer, we move on to treatment.
"We're trying to identify patients at earlier stages," she said. "Our eventual hope is that this would be cost-effective to be used worldwide and that it could be used as a one-day scenario: A patient would come in the morning and test for high risk human papillomavirus (HPV). If they were positive for HPV, they would go on to have the visualization of OCT testing and then between those two, we could determine if the patient has precancerous dysplasia. They could then be treated on the spot, the same day."
Tresser refers to HPV because cervical cancer, the second-greatest cause of cancer deaths in women, is directly linked to the high-risk types HPV. It's the link between cervical cancer and HPV that has made it possible to identify patients at high risk of cervical cancer by testing for the HPV virus.
Imalux recently reported early results on two studies to determine the diagnostic efficacy of real-time OCT. Both IRB-approved studies took place in China in partnership with the Peking University (Peking), Shenzhen Hospital (Shenzhen) and the Renmin Hospital (Buyi-Miao Autonomous District of Guizhou Province).
Some 2,000 women participated in the studies, which gathered 2,800 OCT images. Those images were compared to diagnostic impressions and pathologic findings to determine the accuracy of OCT. The studies both yielded the statistically significant abilities of OCT to differentiate grades of pre-invasive cervical dysplasia prior to biopsy.
"These studies showed that we could use Imalux's Niris Imaging System in both high- and low-resource settings with the intent to improve women's healthcare globally," Tresser said. "OCT allows for very small details in tissue to be appreciated. Our current system provides a resolution that is approximately 10 microns to 15 microns in depth resolution, which is up to 100 times the resolution available in standard ultrasound."
While ultrasound uses sound, OCT uses light. "OCT doesn't penetrate tissue as well as ultrasound," she said. "It's used at the surface to examine tissue changes."
Imalux's Niris received FDA clearance in 2005. Since then, Tresser said that in working with researchers at the Cleveland Clinic, it was discovered that OCT could more precisely identify different types of disease. That's when the current studies were launched in China.
"We found that, after reviewing the first set of 300 patients, we were able to look at data afterward and saw the epithelium became brighter as the stage of cancer advanced," Tresser said. "We were able to see there was a change in brightness along the stages of cancer."
More specific details of those studies will be presented at the 25th International Papillomavirus Conference in Malmo, Sweden in May.
"Now we're at the point that we're trying to create a computer algorithm to help clinicians, in real time, see those changes in brightness to differentiate the early stages of cancer," she said.
Tresser said the company has been working with a prototype version of Niris and will likely have a commercially viable system by 2010 and a complete computer-aided diagnostic system by 2014.
"Over the next three years, we plan to study approximately 3,000 patients," she said. "We may decide to go back to the FDA if we build a system specifically for cervical cancer."