Sunday, December 8, 2013

Study Indicates Highly Effective HPV Vaccine Is Underutilized

Cancer is a dirty word. For some, so is vaccination. And where these two circles collide, a deadly disease can flourish. The Human Papillomavirus (HPV) vaccine is an easy, highly effective way to prevent some of the most grisly cancers known to man; however, a new study conducted by the American Cancer Society suggests that the very people who would benefit most strongly from its protection are all too often unaware of its value.

HPV refers to a group of over 150 viruses that infect the superficial cells of the cervix, genitals, anus, and throat. The virus enters these surface cells, also known as epithelial cells, through minuscule cuts or abrasions made during sexual contact. One inside the cell, the virus hijacks the nucleus and replicates its own genetic code tens or hundreds of times. The infected host can then transmit the virus to his or her sexual partner(s), and the cycle begins again. In fact, HPV is the most common sexually transmitted disease in the country and is estimated to affect more than 50% of the population at some point during their lives.

It can take months or even years to detect an HPV infection, partly because many individuals who carry the virus show no symptoms. Those who do often develop genital warts, the so-called papillomas from which the virus derives its name. Most host immune systems are ultimately able to clear the virus without treatment, but some will go on to develop abnormal cells in the affected area. These cells carry a high risk for unregulated growth and proliferation; unchecked, they can blossom into malignancy - the driving force behind cancer.

Fortunately, HPV is preventable - but only if an individual is immunized before coming into contact with the virus. This means that vaccination is most effective when given in early adolescence. The HPV vaccine consists of a three-dose series: one dose, followed by another 1-2 months later, and a final dose 6 months after the first. Two vaccines against HPV have been approved by the FDA: Gardasil and Cervarix. Both of these shots can be given starting at age 9, and protect against the viral strains that cause most cancers, HPV16 and HPV18. Gardasil also fights HPV6 and HPV11, two of the strains that often cause genital warts.

Despite the fact that these immunizations are widely available, many of those who are at risk for contracting HPV and related cancers know surprisingly little about their existence or effectiveness. At a conference in Atlanta this past weekend, the American Cancer Society's director of health disparities research, Kassandra I. Alcaraz, spoke about a recent survey that revealed a need for better education regarding HPV vaccination among medically underserved populations. Out of more than 1400 individuals who were targeted for their high-risk status, only 30% reported an understanding of the benefits of the HPV vaccine. This percentage dropped to just 22% for non-Hispanic Black respondents. More than three-quarters of respondents reported never having spoken to their doctor about the vaccine at all. Meanwhile, the underserved, minority populations targeted for this study - low-income, Black, and Hispanic women - tend to experience a much higher incidence of HPV-related cancers and die from them at much higher rates than their white, middle-to-upper class counterparts.

Alcaraz also noted that only a third of teenage girls are immunized with the full HPV series, a number that markedly undermines the ACS's wider goal of primary prevention. In short, she said, “the HPV vaccine is a long way from reaching its potential.”

Health care providers can improve this situation not only by discussing the shot with all patients (and parents of patients) who are eligible to receive it, but also by heavily emphasizing its effectiveness. In Alcaraz's view, this is the most pressing concern. "Uncertainty [about the vaccine's effectiveness] may influence decision-making about getting vaccinated," she said. "It hinders our ability to reduce cervical cancer incidence and mortality and reduce disparities in cervical cancer." Alcaraz continued, "Our research suggests efforts should go beyond merely increasing awareness of the availability of the vaccine and focus on making sure people know it is effective.”

As always, those on the front lines of the fight against vaccine-preventable diseases have their work cut out for them.

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