Have you or a loved one ever had an abnormal Pap smear result? If precancerous cells were identified, the cause was almost undoubtedly infection with human papillomavirus (HPV). Almost all cases of cervical cancer arise because of infection with this virus. Yet a vaccine can prevent infection with the strains that most commonly cause cervical cancer.
A vaccine against cancer. It’s true.
For the vaccine to work, though, a woman must have it before HPV infects her. You may find it difficult to look at your daughter, especially a pre-teen daughter, and think of that scenario. But the fact is that even if your daughter avoids all sexual contact until, say, her wedding night, she can still contract HPV from her partner. It happens to be the most common sexually transmitted infection.
About 20 million Americans have an HPV infection, and 6 million people become newly infected every year. Half of the people who are ever sexually active pick up an HPV infection in a lifetime. That means your daughter, even if she waits until her wedding night, has a 1 in 2 chance of contracting the virus. Unless it’s a strain that causes genital warts, HPV usually produces no symptoms, and the infected person doesn’t even know they’ve been infected.
Until the cancer shows up.
And it can show up in more places than the cervix. This virus, you see, favors a certain kind of tissue, one that happens to be present in several parts of you. This tissue, a type of epithelium, is a thin layer of the skin and mucous membranes. It’s available for viral invasion in the cervix, vagina, vulva, anus, and the mouth and pharynx. In fact, HPV is poised to replace tobacco as the major cause of oral cancers in the United States.
The virus can even sometimes pass from mother to child, causing recurrent respiratory papillomatosis, or warts in the throat that must be removed periodically and can sometimes become cancerous. It strikes about 2000 children each year in the United States.
How does a virus cause cancer? To understand that, you must first understand cancer. You may know that cells reproduce by dividing, and that cancer occurs when cells divide out of control. Behind most cancers is a malfunction in the molecules that tell cells to stop dividing. These molecules operate in a chain reaction of signaling, like a series of well-timed stoplights along a boulevard. If one starts sending an inappropriate “go” signal or fails to send a “stop” signal, the cell divides, making more cells just like it that also lack the right signals. If your body’s immune system doesn’t halt this inappropriate growth, we call it cancer.
The blueprint for building these “stop” molecules is in your genes, in your DNA sequences. As a virus, HPV also requires a blueprint to make more viruses. Viruses use the division machinery of the host cell—in you—to achieve reproduction by stealthily inserting their own DNA blueprint into the host DNA.
Sometimes, when it’s finished with the host, a virus leaves a little bit of its DNA behind. If that leftover DNA is in the middle of the blueprint for a “stop” molecule, the cell won’t even notice. It will use the contaminated instructions to build a molecule, one that no longer functions in stopping cell division. The result can be cancer.
Of the 150 HPV types or strains, about 40 of which pass through sexual contact, two in particular are associated with cancer, types 16 and 18. They are the ones that may persist for years and eventually change the cellular blueprint. The vaccines developed against those two strains are, therefore, anti-cancer vaccines.
Without a successful viral infection, viral DNA can’t disrupt your DNA. That’s what the HPV vaccine achieves against the two strains responsible for about 70% of cervical cancers. Recent high-profile people have made claims about negative effects of this vaccine, claims that have been thoroughly debunked. The Centers for Disease Control and Prevention as always offers accurate information about the side effects associated with available HPV vaccines.
This achievement against cancer, including prevention of almost 100% of precancerous cervical changes related to types 16 and 18, is important.
Worldwide, a half million women receive a cervical cancer diagnosis each year, and 250,000 women die from it. These women are somebody’s daughter, wife, sister, friend. Women from all kinds of backgrounds, with all kinds of sexual histories.
Women whose precancerous cervical changes are identified in time often still must undergo uncomfortable and sometimes painful procedures to get rid of the precancerous cells. These invasive procedures include cone biopsies that require shots to numb the cervix and removal of a chunk of tissue from it. Cone biopsies carry a risk of causing infertility or miscarriage or preterm delivery. A vaccine for your daughter could prevent it all.
HPV doesn’t care if your daughter has had sex before. It’s equally oblivious to whether the epithelium it infects is in the cervix or in the mouth or pharynx or in an adult or a child. What it does respond to is antibodies that a body makes in response to the vaccine stimulus.
Even if your daughter’s first and only sex partner passes along one of the cancer-associated strains, if she’s been vaccinated, her antibodies will take that virus out cold. It’s a straightforward prevention against a lifetime of worry—and a premature death.
For more info: Facts about the HPV vaccine from the National Cancer Institute
By Emily Willingham
Image courtesy of CDC
