• 7/24/2004
  • Austin, TX
  • By Linda Marsa
  • LA TIMES

An experimental imaging tool could lead to faster diagnosis, fewer false positive results and better follow-up than the current colposcopy.

For many women, suspicious results from a cervical cancer screening may be just the beginning of a lengthy, and anxiety-filled, diagnostic process. They often must undergo a couple of follow-up tests and wait several weeks before receiving a definite answer.

Not only could an experimental fiber optic device help doctors make a diagnosis much more efficiently than current methods, it also may eventually enable them to do on-the-spot treatment.

“This tool could be a real advance over what we have,” says Dr. Daniel C. Sullivan, head of the cancer imaging program for the National Cancer Institute in Bethesda, Md. “It has the potential to be cheaper, quicker, and more accurate.”

Every year, about 13,000 American women are diagnosed with cervical cancer, which has a 92% survival rate if treated in its early stages. The conventional screening for cervical cancer is a Pap smear, in which a swab of cervical tissue is examined under a microscope by a trained technician.

When abnormal cells are detected, gynecologists visually inspect the cervix using a colposcope, a large electric microscope attached to a bright light. If they see abnormal cells, they’ll perform a biopsy, in which a tissue sample is snipped from the cervix and shipped to a lab for further evaluation.

However, colposcopy results are prone to human error: Cancers can be missed, or, in half the cases, the colposcope gives false positive readings that prompt needless, costly and painful biopsies.

“Diagnosis is very subjective and relies on the doctor having very good visual recognition skills,” says Rebecca Richards-Kortum, a biomedical engineer at the University of Texas at Austin and a co-inventor of the new optical imaging tool.

In addition, the delay between the initial screening and the eventual diagnosis can be six weeks or more, causing a great deal of anxiety and uncertainty. Some women fail to return for follow-up visits, meaning they may not get the correct diagnosis or, if necessary, treatment.

The new optical wands-designed to replace the colposcope examination, not the routine Pap smear-could shorten the time required for diagnosis, decrease the false positive rate (thereby eliminating unnecessary biopsies) and ensure that women receive adequate follow up.

The diagnostic device works by shining natural and ultraviolet light onto the cervix. Precancerous and cancerous cells reflect these light waves differently than normal cells, says Sullivan.

The pencil-thin fiber optic probe can also pick up other telltale signs of cancer, such as higher metabolic activity (because cancer cells divide faster than normal cells) or the presence of more red blood cells (which indicates that new blood vessels have been formed to ferry the nutrients and oxygen tumors need to survive), experts say. All this information is fed into a computer, which can determine immediately whether cells are cancerous.

Early tests indicate that this device may be more reliable than visual exams by physicians.

In a study of more than 100 women last year at the University of Texas at Austin and the M.D. Anderson Cancer Center in Houston, the probe reduced the rate of false positives by 50%, which experts estimate could save more than $600 million annually in healthcare costs in the United States alone. A larger test of 800 women comparing colposcopy with the optical device was recently completed, and results will be released within the next year.

OCF Note: If this device proves to be valuable in cervical cancer, its applications in oral cancer will be following.