You may be at increased risk for a number of deadly cancers and not even know it.

Despite all the media coverage of actress Farrah Fawcett’s recent death, few reporters thought to ask what may have led to the 62-year-old’s deadly case of anal cancer.

Little-known fact: The majority of anal and cervical cancers — and most cancers affecting the penis and oral cavity (mouth, throat and sinus cavities) — are linked to the human papillomavirus (HPV), the most common sexually transmitted infection in the US.

Each year, about 5,000 Americans are diagnosed with anal cancer… approximately 11,000 women are found to have cervical cancer… an estimated 1,500 American men are diagnosed with penile cancer… and some 34,000 Americans are found to have oral cancer.

Why you should be informed about HPV: Even if you’ve been in a monogamous sexual relationship for years, you may unknowingly be carrying the potentially deadly virus. At least half of all sexually active men and women in the US will be infected with HPV at some point in their lives, and an estimated 20 million Americans are currently carrying the virus.

CANCER-CAUSING HPVs

There are more than 100 strains of viruses in the papilloma family. HPV is a well-known cause of warts on the genitals and elsewhere on the body (such as on the hands or feet). Two strains of HPV — known as type 6 and type 11 — lead to genital warts, while more than 30 strains can cause warts on other parts of the body.

Important: Even though genital warts may be emotionally disturbing, they do not turn into cancer.

All the remaining types of HPV have cancer-causing (oncogenic) potential. Of the high-risk strains, two — known as type 16 and type 18 — account for about 70% of all cases of cervical cancer, as well as most cases of anal cancer. These strains of HPV also can infect the penis, the vagina and the mouth.

A HIDDEN THREAT

Infections due to cancer-causing strains of HPV usually go undetected because they do not cause warts or any other signs or symptoms.

Both women and men who are infected can unknowingly transmit the virus — usually during sexual encounters (vaginal, anal or oral sex). The virus enters the body through cuts or tiny tears in the outer layer of the skin in the vagina, cervix, penis, anus and mouth. Because HPV is spread through skin-to-skin contact, it’s possible that kissing is another route of transmission, but the virus is usually transmitted sexually.

The good news is that the body’s immune system effectively eliminates the cancer-causing virus in about 90% of HPV infections — usually within two years. When the virus stays in the body beyond two years, it is considered chronic, and the risk for cancer of the genitals, cervix, anus or oral cavity rises.

ARE YOU AT RISK?

Most HPV infections are transmitted through sexual activity, but about 10% to 15% of the population become infected via nonsexual sources that have not yet been identified. In general, the risk for HPV infection is higher for people with impaired immunity — for example, anyone undergoing chemotherapy or those with diabetes or an autoimmune disease, such as lupus or rheumatoid arthritis, and for people who have many sexual partners or who use devices that cause tears (even very tiny ones) in the skin of the genitals, anus or mouth.

Startling new finding: A common ingredient in many vaginal spermicides, nonoxynol-9, triples a woman’s risk for HPV infection. It damages the lining of the vagina and makes it easier for the virus to enter through the skin.

TESTING AND DIAGNOSIS

Precancerous changes to cells in the cervix can be detected by a Pap smear — named after physician Georgios Papanikolaou, who invented the test. If a woman’s Pap results are described as atypical, she is advised to undergo a test that checks for one or more of 13 cancer-causing HPV types.

New finding: A study of 130,000 women published in The New England Journal of Medicine found that a test used to check for HPV could replace the Pap test at some point. Women who got the HPV test were 37% less likely to die due to cervical cancer than those who received Pap tests, suggesting that the HPV test identifies cervical cancer sooner than a Pap test.

THE HPV VACCINE

Gardasil, a vaccine that prevents infection from four strains of HPV — the high-cancer-risk types 16 and 18, as well as the genital wart–causing 6 and 11 — was approved by the FDA in 2006.

How it’s used: The Centers for Disease Control and Prevention (CDC) recommends Gardasil for girls/young women ages nine through 26. There has been a push to recommend the vaccine for young men to protect both them and their future partners. But recent data found that Gardasil protected men only from the genital wart–causing 6 and 11 types of HPV — but not from the cancer-causing strains.

Latest development: A controversial new study published in the Journal of the American Medical Association found some serious adverse effects, including death, after Gardasil use. Discuss the risks and benefits of the vaccine with your physician.

OTHER PREVENTIVE STEPS

Using a condom reduces — but does not eliminate — risk for HPV infection in women and men. This is because the virus can occur in areas that aren’t covered by a condom, and it can be spread by hand-to-mouth contact. Being in a mutually monogamous relationship with someone who has had few or no previous partners also curbs risk.

To protect yourself: Women are advised to have Pap tests to identify cervical cell changes — every three years if the last test results were normal. If abnormal, an annual Pap test is recommended until the results are normal for three consecutive years.

Women who use spermicides that contain nonoxynol-9 (including male condoms that use this ingredient) to prevent pregnancy should consider switching from this form of birth control to some other method, such as oral contraceptives or cervical caps. Both men and women should ask for an oral cancer check during each dental visit. And men should regularly check for signs of penile cancer, such as visible bumps or ulcers.