New human papilloma virus serotype are being discovered almost monthly and some of the old types are turning out to have more malignant potential than once thought.
But because physicians lack an inexpensive, widely available test to separate relatively harmless HPVs from dangerous ones, they are left to figure out whether good management means seeking out esoteric tests or treating all HPV patients the same, speakers said here at an American College of Obstetrics and Gynecology meeting.
Of the 56 recognized HPVs, types 16 and 18 probably pose the greatest risk for genital cancers, said Dr. Ralph M. Richart, a professor of pathology at Columbia University in New York. When cytologic or histologic exams of a cervical biopsy show that a patient has little or no dysplasia, it may be tempting to conclude that her risk for future neoplasia is low. But such a lab report doesn’t rule out infection with a high-risk HPV type, and the patient’s prognosis remains “indeterminate” unless the viral type is identified, said Dr. Richart.
Until recently, HPV types 6 and 11 were thought to confer no risk of malignancy. But a trickle of reports that these viruses have been found in cancers of the cervix, vulva, and penis have moved them to the “low risk” category, he said. Clinically, that means doctors “cannot ignore an HPV 6 or 11 lesion and say it will never, ever be associated with cancer.”
In many instances, knowing the viral type means “we can predict the course of disease,” says Dr. Richard. The rationale for viral typing is growing, and in the future he expects that patients infected with virulent strains such as HPV 18 will be treated and followed more closely than other patients.
The problem is that identifying strains of HPV generally require DNA hybridization techniques, which are time-consuming and available only in research settings. Though these tests may be practical for rare genetic disorders, the cost is probably prohibitive for an infection as common as HPV.
When inexpensive, rapid diagnostic tests for HPV serotypes come on line, “I will employ them routinely,” Dr. Sebastian Faro told MWN. For the moment, “we’re in a holding pattern, trying to decide what’s best for the patient,” says the Baylor professor of obstetrics and gynecology.
Finding out whether a patient has one of the HPV serotypes that research labs can identify now runs between $300 and $400, and “I think we need to consider the cost factors,” Dr. Faro said.
Much of the HPV infection he sees is in patients who are “young and mobile.” Because these 16- to 25-year-olds are likely to “go off to college or be transferred,” Dr. Faro has elected to treat their lesions without knowing the exact HPV type involved. He advocates “limited treatment for limited involvement,” starting with trichloroacetic acid. For more severe lesions, he favors laser therapy followed by 5-fluorouracil.
All patients with cervical dysplasia and HPV infection must be treated promptly, insisted Dr. Faro. In the absence of atypia, he believes doctors can elect close observation if–and only if -they can rely on the patient to return for frequent examinations.
On the other hand, overtreatment may be taking place in another situation. “Physicians have told me that 30% to 40% of their patients have condyloma of the introitus and vagina,” Dr. Richart said. But when he retests biopsy samples from the introitus and hymenal ring with DNA probes, he has found them “almost uniformly negative” for HPV. “Just because the pathologist says its condyloma doesn’t mean it is.”
Small bumps around the introitus are often entirely normal, noted Dr. Richart, and the HPV types present in most acuminate warts are benign. Condyloma still merits treatment, however, because the infection is sexually transmitted.