STD Awareness: The Vaginal Microbiome and Cervical Cancer

Cervical cancer is caused by human papillomavirus (HPV), which has been nicknamed “the common cold of STDs” — because pretty much every sexually active person will get it at some point. Luckily, that scary stat is poised to change as more people receive the HPV vaccination, which protects against nine major strains of the virus.

HPV jumps easily from person to person, spread by pretty much all types of sexual contact. For most people, the infection clears up within 8 to 13 months, but sometimes the infection develops into a chronic condition, which increases risk for certain cancers — including cervical cancer, but also cancers of the anus, genitals, and throat. Unfortunately, it’s hard to predict if your immune system will vanquish your infection, or if you’ll develop a chronic infection.

Members of the lactobacilli family, keeping vaginas healthy across the globe. Image: Josef Reischig

Luckily, the vagina has some tricks up its sleeve to protect itself from HPV, and some of its best weapons are bacteria. Yep — a healthy vagina isn’t germ-free. To the contrary, it needs lactobacilli and other beneficial microbes to maintain a healthy environment. Bacteria from the Lactobacillus genus produce lactic acid and other chemicals, which help keep dangerous bugs away. Vaginal environments in which Lactobacillus gasseri dominate, for example, are more likely to clear HPV infections. L. crispatus helps trap HIV in a thick mucus, reducing infection risk. Other lactobacilli species secrete chemicals that ward off yeast infections. Sometimes, however, good bacteria lose this turf war, and “bad guys” move in.


The population of microbes that live in your vagina are known collectively as the vaginal microbiome.


University of Arizona researchers in Phoenix performed a “census” of the vaginal microbial communities of 100 premenopausal women. They learned that women who have cervical cancer or precancerous abnormalities have drastically different vaginal microbiomes. Healthy vaginas were generally dominated by lactobacilli, but as cervical health declined, their populations declined, and “bad” bacteria took over. One such bad guy, called Sneathia, was linked to HPV infection, precancer, and cervical cancer.

Which Came First?

Finding a new vaginal “bad guy” was exciting, and Sneathia had previously been linked to other gynecological problems, ranging from bacterial vaginosis to pregnancy complications. But the researchers were looking at a snapshot in time — they didn’t know what came first, the Sneathia or the cervical abnormalities. Were lactobacilli protecting the cervix whereas Sneathia were harming it, or did a chronic HPV infection set the stage for Sneathia to move in and thrive? It’s a real “chicken-and-egg” conundrum. Continue reading

STD Awareness: Winning One War on Cancer

Cancer starts with the uncontrolled division of cells.

The developed world is in the midst of a huge nosedive in genital warts and cervical “precancer” — all thanks to the human papillomavirus (HPV) vaccine. This simple shot trains the immune system to defend itself against HPV, a virus that causes genital warts and several types of cancer. Most sexually active people will be exposed to it in their lifetimes — it’s even been nicknamed the “common cold” of sexually transmitted infections.

Gardasil 9 protects against seven strains of HPV that collectively cause 90% of cervical cancers and anal cancers, plus the two HPV strains that are jointly responsible for 90% of genital warts. Vaccination also reduces the frequency of “precancers,” which are cellular abnormalities that can be treated before progressing into full-fledged cancer — meaning less time, money, and anxiety spent dealing with follow-up procedures and treatments.


The HPV vaccine is an anti-cancer vaccine.


The vaccine is safe and effective — and when we say “effective,” we mean it could lead to the eradication of HPV, and with it the cancers it causes. A recent analysis of 66 million vaccine recipients published in The Lancet points to plummeting rates of genital warts and precancer. Among teenage girls, there was an 83% drop in HPV-16 and HPV-18 infections (the two strains of HPV that together cause 70% of cervical cancers) — and cervical precancers were cut in half.

The most dramatic gains were made in countries that offered the HPV vaccine to both boys and girls. Additionally, there were even decreases in the HPV strains that aren’t covered by the vaccine — evidence of “cross-protection,” the phenomenon in which the immune system recognizes close relatives of the viruses it has been trained to attack. Even people who did not receive the vaccine were less likely to catch the virus, simply because their risk was reduced if their partners were vaccinated. Continue reading

From HPV to Cancer to Dry Mouth

Despite what a lot of people might think, oral sex is sex — not “third base,” not “everything but” — carrying with it the potential for both pleasure and disease transmission. That includes oral transmission of human papillomavirus (HPV), which can lead to head-and-neck cancer (aka oral cancer, aka oropharyngeal cancer). Unfortunately, because so many of us have a lax attitude toward it, fewer people take precautions when engaging in oral sex, and are less likely to use condoms or dental dams.


A head-and-neck cancer epidemic is striking younger people, spurred by HPV.


Head-and-neck cancer — which can strike anywhere from the lips to the larynx, and up into the sinuses and nasal cavity — is caused by several risk factors, chief among them oral infection with HPV. When HPV causes head-and-neck cancer, it usually occurs at the base of the tongue, at the back of the throat, in the tonsils, or in the soft palate.

HPV can be spread by most sexual activities, including vaginal, anal, and oral sex, as well as by rubbing genitals together. Although HPV is most famously associated with cervical cancer, it’s actually driving more cases of head-and-neck cancer in the United States.

It’s Oral, Head, and Neck Cancer Awareness Week — a time to learn about how head-and-neck cancer has changed over the years, what consequences it can have for survivors, and how it can be prevented in the first place.

A Changing Patient Profile

In 2017, scientists reported that oral HPV infections with cancer-causing strains of the virus are five times more common in men than in women, and that, likewise, HPV-associated head-and-neck cancers are more likely to strike men. That same year, researchers also reported that, in the United States, head-and-neck cancer among men has surpassed cervical cancer among women. As the years pass by, head-and-neck cancer rates are expected to continue to skew even more heavily toward the male population. Continue reading

STD Awareness: Can Older Adults Receive the HPV Vaccine?

female-patient-with-female-doctorWhen the human papillomavirus (HPV) vaccines were introduced, a lot of people were excited about protection from a sexually transmitted virus that could cause cancers, including cervical cancer, anal cancer, and head-and-neck cancer. It wasn’t just any old vaccine, it was a shot that could prevent cancer. Cancer!

In fact, a lot of people were disappointed they were too old to take advantage of an anti-cancer vaccine, which was initially approved for people as old as 26. We were given a lot of reasons why people above that age were “too old,” such as the assumption that anyone older than 26 has probably been sexually active for years and would have already contracted the most common strains of HPV.


While getting vaccinated before becoming sexually active is optimal, the HPV vaccine can still benefit people who have already had sex.


But there are compelling reasons to vaccinate people in their late 20s and beyond. In fact, Gardasil 9 was recently approved for people as old as 45. That’s great news for those of us who missed out on the HPV vaccine the first time around. We might never have had any sexual contact, and therefore were never at risk for catching the sexually transmitted virus. We might have found ourselves widowed or divorced after years or decades of monogamy. We might have been sexually active with multiple partners during that time. Whatever our circumstances, those of us who are 45 or younger can now consider HPV vaccination.

HPV and the “Older” Individual

When Cervarix and Gardasil, the first HPV vaccines, were released, they only protected against two cancer-causing HPV strains, HPV-16 and HPV-18, which are responsible for 70 percent of cervical cancers (Gardasil protects against two additional wart-causing HPV strains). A few years ago, Gardasil 9 hit the market, targeting five additional cancer-causing HPV strains — increasing the chances that even sexually active recipients could be protected from HPV strains they hadn’t encountered. Continue reading

STD Awareness: Eliminating HPV-Related Cancers

Earlier this month, every major cancer center and organization in the country released a joint statement calling for the elimination of cervical cancer, along with all other HPV-related cancers. The elimination of a large swath of cancers might sound like a tall order — so far, we’ve only eradicated two viruses from the planet: smallpox and rinderpest. And we’re on the brink of getting rid of a third, the virus that causes polio.

But doing away with human papillomavirus (HPV) would herald a new chapter in disease eradication, because HPV causes cancer, meaning that eradicating HPV will eradicate the cancers caused by it. And the good news is we have all the tools we need to wipe HPV off the face of the earth — we just need to use them.


The tools to wipe a large class of cancers off the face of the earth are right under our noses — we just have to use them.


A quick rundown on HPV is in order. It’s the most common sexually transmitted infection in the world, and causes multiple cancers — cervical, head and neck, anal, vulvar, vaginal, and penile. While it’s most well-known for causing cervical cancer, here in the United States it is transitioning away from its old job, causing more head-and-neck cancers than cervical cancers. Nearly all sexually active people will be infected with HPV at least once in their lives, and though only a fraction of infections progress to cancer, its ubiquity means it still causes hundreds of thousands of cancers every year. In the United States, around 41,000 HPV-related cancers are diagnosed annually, while more than 600,000 are diagnosed worldwide. Continue reading

STD Awareness: Fighting Cervical Cancer Across the World

Tomorrow kicks off World Immunization Week, a reminder that, just as disease can cross borders, so should our efforts to prevent it. Especially when we have an effective vaccine for one of the world’s top causes of cancer — but the people who need it most are less likely to get it.

Almost 90 percent of cervical-cancer deaths strike women in developing countries, where it is the second-most common cancer among women. In fact, over vast swaths of Africa, cervical cancer is the No. 1 cause of cancer death in women. (In the United States, it doesn’t even crack the Top 10.) While cervical cancer rates are holding steady in the developed world, in the coming decades they are projected to increase sharply in less developed regions.


More than 9 out of 10 cervical cancers strike women in countries with no HPV vaccination programs.


Since 2006 there has been a vaccine for human papillomavirus (HPV), the virus that causes cervical cancer. Unfortunately, while this vaccine is making impressive strides in the developed world, it is almost out of reach in the developing world, where it could save the most lives. To fully realize this vaccine’s potential, it needs to be distributed worldwide — not just within rich countries that can afford it.

Fighting Cervical Cancer in the Developed World

HPV has been nicknamed “the common cold of STDs” — because pretty much every sexually active person will get it at some point. It can be transmitted by vaginal, anal, and oral sex, as well as by rubbing genitals together, even without penetration. HPV can cause cancers of the throat, anus, vagina, vulva, and penis — but is most “famous” for causing cancer of the cervix (the tissue that connects the vagina to the uterus). If you have a cervix, there are two big things you can do to protect its health: receive regular Pap testing after becoming sexually active, and get vaccinated against HPV before becoming sexually active. When you take both of these steps, you’ll maximize what modern medicine has to offer. Continue reading

STD Awareness: Is HPV Now a “Men’s Disease”?

Human papillomavirus, or HPV, is most notorious for causing cervical cancer — making it, in many people’s minds, a “women’s disease.” But this gender-blind sexually transmitted virus can cause cancer in any cell it infects, and is associated with cancers of the cervix, anus, vagina, vulva, penis, and mouth and throat — aka oropharyngeal cancer.

While oropharyngeal cancers used to be caused mostly by tobacco, as people quit smoking an increasing proportion is caused by HPV. In the 1980s, only 15 percent of oropharyngeal cancers were caused by HPV, but nowadays the virus is behind 70 percent of them. A 2011 study predicted that the number of HPV-positive oropharyngeal cancers will surpass cervical cancers by 2020.


HPV is rapidly gaining prominence among men.


It’s only 2017, but we’re ahead of schedule. Earlier this year, researchers reported that, in the United States, oropharyngeal cancer is more common among men than are cervical cancers among women — and oropharyngeal cancer rates are increasing in the male population, while they are relatively stagnant among women. These rates are projected to continue climbing, which will skew oropharyngeal cancer even more heavily toward the male population. But, in the public’s imagination, HPV is most well-known for its association with cervical cancer — while most people haven’t even heard of oropharyngeal cancer.

Oropharyngeal Cancer and HPV

Oropharyngeal cancer can strike the inside of your mouth and throat. Risk factors include tobacco (including cigarettes, snuff, and chewing tobacco), marijuana use, alcohol, and oral infection with HPV. HPV can be spread by most sexual activities — including vaginal, anal, and oral sex, as well as “French kissing” and rubbing genitals together. There are many strains of HPV, which come in two main categories: low-risk HPV, which can cause genital warts; and high-risk HPV, which can cause cancer. Continue reading