Tennis legend Martina Navratilova recently announced that her breast cancer had returned and along with it, another surprising diagnosis.

The 66-year-old discovered an enlarged lymph node in her neck. Doctors diagnosed her with Stage 1 throat cancer caused by human papillomavirus (HPV).

Confused about how a sexually transmitted infection can turn into throat cancer? Christopher Iannuzzi, MD, a radiation oncologist at St. Vincent’s Medical Center in Bridgeport explains.

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How does HPV cause cancer?

HPV is the most common sexually transmitted infection. It’s spread through skin-to-skin contact – usually by engaging in oral, vaginal or anal sex with someone who’s infected. Many people with HPV don’t realize they have it because there may be no signs or symptoms.

Most infections go away on their own, but some will last longer and can cause cancer.

“Certain high-risk strains of HPV can persist in the body for years – particularly in a cell type known as a squamous cell that lines certain surfaces of the body such as the throat and the genitalia,” says Dr. Iannuzzi. “This chronic irritation can cause cellular changes that result in cancer.”

According to the Centers for Disease Control and Infection (CDC), HPV can cause cancers of the:

  • Cervix, vagina and vulva in women
  • Penis in men
  • Anus in men and women
  • Back of the throat (called oropharyngeal cancer) in men and women

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What’s the prognosis for HPV-related throat cancer?

Upon her announcement, Navratilova said that she has begun treatment and her prognosis is good.

“Unlike cancer caused by smoking, the prognosis is better for HPV-related throat cancer,” notes Dr. Iannuzzi. “It responds favorably to treatment and is highly curable.”

Symptoms of throat cancer include:

  • Sore throat
  • Earache
  • Difficulty swallowing
  • Weight loss
  • Lump or mass in the neck

How can I prevent HPV?

“The HPV vaccine is effective against the strains of HPV that cause cancer,” says Dr. Iannuzzi.

The CDC recommends two doses of the HPV vaccine administered at ages 11-12 to both boys and girls. The vaccine series is most effective if given before a person is exposed to the virus.

Other ways to protect yourself include using condoms and dental dams during sexual activity.