Cervical cancer almost always starts with a persistent infection from human papillomavirus (HPV)
Cervical cancer develops when cells in the cervix—the lower part of the uterus that connects to the vagina—become abnormal and grow out of control. The overwhelming majority of cases begin with a long-lasting infection from human papillomavirus (HPV), a sexually transmitted virus that most sexually active people encounter at some point. Most HPV infections clear on their own within a year or two, but in some people, certain high-risk types of HPV persist and gradually damage the cervical cells, eventually leading to cancer.
This process typically takes years—often 10 to 15 years or longer—which is why cervical cancer is one of the most preventable cancers when caught early. The slow progression gives screening tests time to detect abnormal cells before they become cancerous, and in many cases before a person even knows they have an infection.
Key Takeaways
- HPV infection is the primary cause of cervical cancer, but most HPV infections clear without treatment within one to two years.
- High-risk HPV types (particularly HPV-16 and HPV-18) are responsible for about 70 percent of cervical cancers.
- Persistent infection combined with other factors—smoking, weakened immunity, long-term hormonal birth control use, or multiple pregnancies—increases the risk that HPV will lead to cancer.
- Abnormal cells develop gradually through stages (dysplasia), giving screening tests a window to detect and treat changes before cancer forms.
How HPV infection leads to cervical cell changes
When HPV infects the cervix, it enters the cells that line the surface. In most people, the immune system recognizes and clears the virus within months. But in others—for reasons not fully understood—the virus persists, and its proteins begin to interfere with the normal growth controls inside cervical cells. Over time, this damage accumulates.
The cervical cells start to look abnormal under a microscope, a condition called dysplasia or cervical intraepithelial neoplasia (CIN). Dysplasia is graded by severity: CIN1 (mild), CIN2 (moderate), or CIN3 (severe). Most cases of mild dysplasia resolve on their own, but moderate and severe dysplasia carry a higher risk of progressing to invasive cancer if left untreated. This is where screening catches the problem: a Pap test or HPV test can detect dysplasia years before it becomes cancer.
Which HPV types cause cervical cancer
Not all HPV types carry the same risk. There are more than 200 known HPV types, but only about a dozen are considered high-risk for cancer. HPV-16 and HPV-18 are responsible for roughly 70 percent of all cervical cancers. Other high-risk types include HPV-31, HPV-33, HPV-45, HPV-52, and a few others. These types produce proteins that directly damage the genes that normally prevent cells from becoming cancerous.
Low-risk HPV types (like HPV-6 and HPV-11) typically cause genital warts but almost never lead to cancer. This distinction is important because it means not every HPV infection carries equal danger, and screening tests can identify which type a person carries.
Other factors that increase cancer risk alongside HPV
HPV infection alone is necessary but not always sufficient for cervical cancer to develop. Several other factors influence whether a persistent infection will progress to cancer. Smoking damages the immune cells in the cervix and makes it harder for the body to clear HPV. A weakened immune system—from HIV, organ transplant medications, or other causes—reduces the body's ability to control the virus. Long-term use of hormonal birth control (five years or longer) is associated with increased risk, though the reason is not entirely clear. Multiple pregnancies may also play a role, possibly through changes in immune function during pregnancy.
Age matters too: cervical cancer is most common in people in their 40s and 50s, reflecting the time needed for HPV to cause progressive damage. It is rare before age 25, which is one reason screening typically begins in the mid-20s rather than earlier.
How screening detects changes before cancer forms
The reason cervical cancer is preventable is that abnormal cells can be found and treated long before they become invasive cancer. A Pap test collects cells from the cervix and examines them under a microscope for dysplasia. An HPV test detects the presence of high-risk HPV DNA. Many screening programs now use HPV testing first, since it is more sensitive at catching infections that might progress.
If screening finds dysplasia, the next step is usually a colposcopy—a magnified examination of the cervix—followed by a biopsy if abnormal areas are visible. If the biopsy confirms CIN2 or CIN3, treatment (usually a procedure to remove the abnormal tissue) can prevent cancer from developing. This is why regular screening is so effective: it interrupts the progression at a stage when treatment is simple and highly successful.
The role of HPV vaccination in prevention
HPV vaccines work by training the immune system to recognize and fight high-risk HPV types before infection occurs. The vaccines protect against HPV-16 and HPV-18 (and in newer versions, additional high-risk types). They are most effective when given before a person becomes sexually active, but they can still provide protection if given later. Vaccination does not treat an existing HPV infection, but it prevents future infections from the types covered.
Because vaccination prevents the initial infection rather than treating it, it is considered prevention rather than treatment. People who are vaccinated still need screening, because the vaccines do not cover all high-risk HPV types and because some people may have been infected before vaccination.
What happens if HPV infection is not detected
If persistent HPV infection goes undetected and untreated dysplasia progresses, the abnormal cells can eventually break through the basement membrane that separates the surface layer of the cervix from deeper tissue. At that point, the cancer is considered invasive and can spread to nearby lymph nodes and other organs. Invasive cervical cancer requires more aggressive treatment—surgery, radiation, chemotherapy, or a combination—and has a lower survival rate than cancer caught at the dysplasia stage.
This is why screening gaps matter. People who have never had a Pap test or HPV test, or who have not been screened in many years, are at much higher risk of developing advanced cervical cancer. In countries with established screening programs, cervical cancer rates have dropped dramatically.
Frequently Asked Questions
Can you get cervical cancer without HPV?
Cervical cancer without HPV is extremely rare—less than 5 percent of cases. A small number of cervical cancers are adenocarcinomas that may develop through a different pathway, but HPV is still involved in most of those. For practical purposes, HPV is the primary cause.
If I have HPV, will I definitely get cervical cancer?
No. Most people who contract HPV clear the infection on their own and never develop cancer. Only a small percentage of people with persistent high-risk HPV infection go on to develop cervical cancer, and that risk is further reduced by screening and treatment of dysplasia.
How long does it take for HPV to turn into cancer?
The process typically takes 10 to 15 years or longer from the initial infection to invasive cancer. This slow progression is why screening can be so effective—there is a long window to detect and treat abnormal cells before they become cancerous.
Can men get cervical cancer?
No, cervical cancer occurs only in people with a cervix. However, HPV can infect men and cause other cancers, including cancers of the throat, anus, and penis. HPV vaccination protects against these cancers in men as well.
Does having HPV mean I have cervical cancer?
No. HPV infection and cervical cancer are not the same thing. Most HPV infections clear without causing any problems. Only persistent infection with high-risk types, combined with other factors, can lead to dysplasia and eventually cancer—and even then, screening and treatment can prevent that progression.