And while most people never know they have the virus, some who are infected with high-risk types of HPV go on to develop cancer of the cervix, anus, vulva, vagina, penis, or oropharynx (the back and sides of the throat, tonsils, and base of the tongue) or some combination of these cancers. Lower-risk types of HPV can cause genital warts, which may appear in the genital and anal areas as well as in the mouth and throat. You’re most likely to get some type of genital HPV infection in your teens or early twenties — shortly after you become sexually active, says Mamta Singhvi, MD, a radiation oncologist in Los Angeles and a board member of the American Sexual Health Association. In most young healthy people, the immune system destroys the HPV virus within a couple of years. But some HPV infections persist, and according to the Centers for Disease Control and Prevention (CDC), HPV infections cause cancer in more than 20,000 women and 13,000 men each year in the United States. Here’s what you need to know about the link between HPV and cancers of the cervix, vagina, anus, and oral cavity, and what you can do to protect yourself.

Cervical Cancer and HPV

The cervix is the passageway from the uterus to the vagina. It’s made up mostly of connective tissue and muscle and, when viewed from the vagina, looks a bit like a doughnut. The American Cancer Society estimates that in 2019, about 13,170 new cases of invasive cervical cancer will be diagnosed in the United States, and about 4,250 women will die from cervical cancer. Nearly all cases are caused by earlier infection with high-risk strains of the HPV virus. Dr. Singhvi says that people with higher numbers of sexual partners and those who began having sex at younger ages may be at higher risk of HPV infection. Smoking also increases HPV risk because it impairs the immune system, making it more challenging to fight off the virus. The good news is that you can lower your risk of cervical cancer by getting the HPV vaccine, using condoms, being in a monogamous relationship, and having regular cervical cancer screenings. The earlier precancerous cell changes are found, the more treatable they are. RELATED: 8 Ways to Prevent HPV or Detect It Early “It’s only if someone goes for years without a checkup or if they have a particularly aggressive type of HPV that it turns into cancer,” says Singhvi. Women usually have no symptoms of early-stage cervical cancer, she says. But once the cancer has progressed, warning signs may appear. The following are possible signs of cervical cancer:

Vaginal bleeding after sexPain during sexUnusual bloody vaginal discharge between periodsLonger or heavier than usual periodsBleeding after menopause

Most precancerous signs can be caught with a Pap smear before the condition progresses to cancer. Women should start getting Pap smears at age 21 and have the test every three years until age 29, according to the cervical cancer screening guidelines of the American College of Physicians. From ages 30 to 65, have a Pap test combined with an HPV test every five years or, if HPV testing isn’t available, have a Pap test every three years. If your Pap smear comes back with abnormal results, your doctor will order a test to determine if the HPV strain is high- or low-risk. If you have a high-risk strain, in-office procedures such as LEEP (loop electrical excision procedure) may be used to shave away the bad cells, allowing healthy tissue to grow in its place. Afterward, you’ll need more frequent Pap and HPV testing until the results come back clear, says David Chelmow, MD, the chair of the department of obstetrics and gynecology at Virginia Commonwealth University’s School of Medicine in Richmond. You may also need screening more frequently if you’re at a higher risk for an HPV infection to develop into cancer. Risks include a weakened immune system, having the human immunodeficiency virus (HIV), or taking immunosuppressant drugs.

Vaginal Cancer and HPV

Each year, about 5,350 women are diagnosed with vaginal cancer in the United States, and about 1,430 die from the condition. HPV is found in most cases of vaginal cancer, according to the American Cancer Society, although it is not the only risk factor: Smoking cigarettes more than doubles the risk of vaginal cancer. Signs and symptoms of cancers of the vagina and vulva are similar to those of cervical cancer, says Debbie Saslow, PhD, the senior director of HPV-related and women’s cancers at the American Cancer Society. They include:

Abnormal vaginal bleedingPain, particularly during sexual intercourseUnusual vaginal discharge

If you have any of these symptoms, see your doctor right away. RELATED: 10 Cancer Screening Tests Women Need to Know About

Anal Cancer and HPV

Another cancer that can be caused by HPV is anal cancer. According to the American Cancer Society, there are nearly 8,300 new cases of anal cancer in the United States each year — about 5,530 in women and 2,770 in men. Roughly 1,280 people die each year from anal cancer in the United States. Anal sex is not the only way to get HPV that leads to anal cancer, says Joel Palefsky, MD, an infectious disease specialist and a professor of medicine at the University of California in San Francisco. “Women can get it without ever having anal sex,” Dr. Palefsky says. “There is a clear relationship between an infection in the cervix and having an infection in the anus.” Other risk factors are chronic inflammation, tears in the skin near the anus, being HIV-positive, and taking immunosuppressant drugs. In addition, women who have had cervical cancer, precancerous cervical cells, or HPV-related cancer or precancer in the vulva are at slightly higher risk. Doctors have no specific guidelines for when to screen for anal cancer, says Palefsky. “I don’t think all women need to go to their primary care provider for screening. The average healthy woman need not be screened unless she falls into a risk group or has symptoms.” Palefsky screens his HIV-positive patients for anal cancer annually; for those who are at high risk but don’t have HIV, he screens every two to three years. Like cervical cancer, anal cancer often produces no symptoms until it has progressed. In its advanced stages, anal cancer symptoms may include:

Lumps near the anusTenderness or hard spots in the areaAnal bleeding or dischargeAn unusual change in bowel movements (either constipation or loose stools)Hemorrhoids that don’t go away after treatment

Palefsky says anal cancer was discovered in many of his patients after they experienced recurrent anal bleeding and went in for surgery to remove hemorrhoids. Your doctor may be able to detect anal cancer through a digital anorectal exam, says Palefsky. During this test, a physician uses a gloved finger to feel for a lump or bump that may indicate cancer. Another type of screening, known as cytology, is similar to a Pap smear. The doctor uses a swab to collect anal cells to look for changes that point to precancer or cancer.

Oropharyngeal Cancers and HPV

About 14,800 cases of HPV-associated oropharyngeal (mouth and throat) cancer are diagnosed in men in the United States each year, and another 3,400 cases are diagnosed in women, according to CDC estimates. Frequent and heavy alcohol consumption and tobacco use also raise the risk for oropharyngeal cancer, but in two out of three cases, the cancer is linked to HPV infection, according to the American Cancer Society. Symptoms that may indicate oropharyngeal cancer include:

A sore throat that doesn’t go awayPain or difficulty swallowingTrouble opening the mouth fullyA lump in the throat or neck areaA white patch on the tongue or elsewhere in the mouth that doesn’t go away

Like many cancers, oropharyngeal cancers have a better chance of being cured when caught early, so see your doctor if you have any of these signs or symptoms.

How to Prevent HPV Infection

“The silver lining is we know what causes these cancers,” Singhvi says. “To be able to say HPV is behind a lot of these [cancers] allows us to develop vaccines, screening, and education.” Both the American College of Obstetricians and Gynecologists and the CDC recommend vaccination against HPV at age 11 or 12 for both boys and girls, but it can be done as early as age 9 and as late as age 45. The vaccine currently available in the United States, Gardasil 9 (human papillomavirus 9-valent), protects against infection from both HPV 16 and 18, which cause the majority of cancers related to the virus, as well as five other types that can cause cancer: 31, 33, 45, 52, and 58. Other ways to lower your risk of an HPV infection include using latex condoms every time you have sex, and having sex only with a person who only has sex with you. Additional reporting by Ingrid Strauch.