It’s not very often that we find an identifiable cause for cancer. Science strives to figure out the big question that patients with cancer have: why did I get this? We know that smoking can increase your risks for lung cancer, but not all those who smoke will have lung cancer, and not all lung cancers are in those that smoke. Similarly, colon cancer has been linked to diet and genetics, but many with a healthy diet and no family history have colon cancer. Cervical cancer is different: HPV has been identified as the main culprit.
HPV, or the human papillomavirus, is a sexually transmitted infection that the majority of sexually active people will have at some point in their life. It is usually asymptomatic – no discharge, no pain, no bleeding. For most of us, the HPV infection will be temporary: our bodies will fight it off. However, for some, HPV can linger, ultimately leading to cervical dysplasia and cervical cancer, as well as anal cancer.
How does HPV cause cervical cancer? Does everyone with HPV develop cervical cancer? To answer the first question, the link between HPV and cervical cancer was first discovered in 1980s. HPV is able to get inside cells in the cervix and cause uncontrolled growth, and ultimately cancer. However, HPV is required but not sufficient to cause cervical cancer. Although the vast majority of women with cervical cancer will have HPV, only a small fraction of women with HPV will develop cervical cancer. Why is this? HPV can be eliminated from our bodies by our immune system. For women with a healthy immune system, the HPV can be removed. But many things can lower the immune system, including smoking, stress, steroids, pregnancy, other cancers, or certain medications. The immune system cannot remove HPV, it is able to stay in the cells, and ultimately lead to dysplasia or cancer.
The most common types of cervical cancer, squamous cell carcinoma and adenocarcinoma, have proven links to HPV, and the presence of HPV is often required to confirm the diagnosis. This accounts for more than 90 percent of all cervical cancers. Rare forms of cervical cancer, including clear cell carcinoma, neuroendocrine, and melanoma, may be caused by other factors. However, knowing the link to HPV, women can make efforts to decrease their exposure to HPV. Getting the HPV vaccine, limiting unprotected sex and limiting sexual partners, and getting regular pap tests can reduce the risk of developing cancer. HPV is everywhere – protect yourself!
Burd, EM. Human Papillomavirus and Cervical Cancer. Clinical Microbiology Reviews. Jan 2003. 1-17.