New tests, treatments aid in fight against HPV
Your patient is 22 and sexually active with multiple partners. When she comes into your office with clusters of cauliflower-like bumps around her vulva, you suspect they're warts caused by human papillomavirus (HPV). What's your next move?
Be prepared so that once a definitive diagnosis is made you can offer information on genital HPV, one of the most common but least discussed sexually-transmitted infections. An estimated 24 million Americans are infected with HPV, and as many as one million new HPV infections occur each year.1
Although it's difficult to estimate the overall prevalence of genital HPV infection, current figures suggest that visible genital warts are present in about 1% of sexually active American adults, and that at least 15% have subclinical infection.2 The highest rates of genital HPV infection are found in young adults ages 18 to 28.2
HPV is of significant concern for women because certain types of the virus are the leading cause of cervical cancer. And because HPV can cause visible genital warts, changes on the skin that are visible only through the microscope, or live in the skin without causing any warts at all, it is an infection that presents challenges for patients and providers.
"It is frustrating because the providers can't answer the questions that are posed to them because no one has the answers," remarks Katherine Stone, MD, a medical epidemiologist with the Division of STD Prevention of the Centers for Disease Control and Prevention (CDC) in Atlanta.
"It is still a fairly new area," she says. "We can't grow the virus, and we can't do a blood test for the virus. It's harder to study than the other sexually transmitted diseases."
As research emerges, however, those in the field see encouraging news about HPV, she says.
"HPV is very common, but it may not be a persistent infection," she observes. "The body's immune system may actually deal with it. It's not clear that people remain infectious their whole lifetime. With herpes, they probably do; but with HPV, maybe they don't. HPV is very common, but cervical cancer is actually not that common. Even though a lot of people have HPV, only a very small proportion will go on to develop cancer."
New treatments available
Two new forms of patient-administered treatments for external genital and perianal warts caused by HPV infection have been added to the CDC's newly released 1998 Guidelines for Treatment of Sexually Transmitted Diseases - imiquimod cream and podofilox gel. The cream is marketed under the brand name Aldara by 3M Pharmaceuticals of St. Paul, MN, while the gel is manufactured by Oclassen Pharmaceu-ticals of San Rafael, CA, a subsidiary of Watson Pharmaceuticals of Corona, CA, as Condylox Gel. Both preparations received approval from the U.S. Food and Drug Administration in 1997.
These treatments join the existing provider-administered therapies, such as podophyllin and trichloroacetic acid, cryotherapy, and elec-trocautery, and they broaden treatment options, notes Linda Alexander, PhD, FAAN, president and chief executive officer of the American Social Health Association in Research Triangle Park, NC. Podofilox originally was offered in a topical solution, with the new gel offering fingertip application. The imiquimod cream is the newest in a class of drugs known as immune response modifiers.
"In the past, treatment modalities have been really limited to provider-directed interventions," notes Alexander. "This is something that a patient can use."
A Pap smear often shows abnormalities that can be caused by cervical HPV infections. Many of these abnormal Pap smears get reported as atypical squamous cells of undetermined significance (ASCUS), which turn out to be low-grade squamous epithelial lesions (LSIL), high-grade squamous epithelial lesions, and hidden invasive cancers.3
Because the squamous cells do not meet the criteria for defined epithelial abnormalities, they pose vexing problems for cytopathologists and women's health care providers and leave patients with lingering concerns.
Colposcopy or close follow-up?
A large national study of about 7,000 women, known as the ASCUS/LSIL Triage Study, will evaluate the use of HPV testing as a means of identifying which women with an ASCUS or LSIL diagnosis should go on to colposcopy or remain under close follow-up. The study, begun in late 1996 by the National Cancer Institute in Rockville, MD, will offer follow-up care to participants every six months for three years.
The Hybrid Capture 1 HPV DNA Assay, manufactured by Digene Corp. of Beltsville, MD, is the test included in the multi-year study. Approved by the FDA in 1995, the Hybrid Capture 1 can detect nine high-risk and five low-risk types of HPV, says Whitney Stuart, Digene's HPV product manager.
Although charges vary among labs, costs range from $50 to $100, Stuart says. Digene offers a telephone hotline to help providers with reimbursement questions. (See resource box, p. 50.)
The Hybrid Capture 1 system is now in use in America and may soon be joined by Hybrid Capture II, which can screen for 13 high-risk HPV types and five low-risk types. In addition to HPV, the new technology also will allow for the detection of gonorrhea and chlamydia from a single patient sample. The company is awaiting FDA approval on the new test, Stuart explains.
While such DNA testing offers promise, its utility in clinical practice remains unclear at the present, says Stone of the CDC. Officials look to results of the National Cancer Institute study before recommending such DNA tests as a standard of care.
(Editor's note: Counseling is an important aspect of HPV treatment, and many patients say it is in short supply. Take a look at what HPV patients say about providers in the story at right. Plus, see the brochure, A Practical Guide for the Tongue-Tied: How to Talk With Your Health Care Provider About HPV and Other STDs, inserted in this issue.)
References
1. Centers for Disease Control and Prevention, Division of Sexually Transmitted Diseases Prevention. Sexually Trans-mitted Diseases Surveillance 1995. U.S. Department of Health and Human Services, Public Health Service. Atlanta; September 1996.
2. Koutsky L. Epidemiology of genital human papillomavirus infection. Am J Med 1997; 102:3-8.
3. Titus K. Abnormal Pap smears, ASCUS still ob/gyn puzzle. JAMA 1996; 276:1,014-1,016.
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