Cervical cancer starts in the cells lining the cervix, the narrow opening between the uterus and vagina

Cervical cancer begins when cells in the cervix grow abnormally and become cancerous. Most cervical cancers are caused by infection with human papillomavirus (HPV), a virus spread through sexual contact. Not everyone infected with HPV develops cervical cancer — the body clears most infections on its own within one to two years. But in some people, the virus persists and causes changes to cervical cells that can eventually turn into cancer.

The cervix is the lower part of the uterus that connects to the vagina. Cancer can develop in two types of cells there: squamous cells (which make up most of the cervix) or glandular cells. Squamous cell cervical cancer is more common, accounting for about 80 to 90 percent of cases. Adenocarcinoma, which develops in glandular cells, is less common but often diagnosed at a later stage because it starts higher in the cervix where screening tests may miss it.

Key Takeaways

  • Most cervical cancers are caused by persistent infection with HPV, a virus spread through sexual contact.
  • Cervical cancer develops slowly over years, usually progressing through precancerous cell changes that can be detected and treated before cancer forms.
  • The HPV vaccine prevents infection with the virus types most likely to cause cervical cancer and is most effective when given before sexual activity begins.
  • Regular screening with Pap tests or HPV tests can find precancerous changes or early cancer when treatment is most effective.

How HPV infection leads to cervical cancer

HPV is a common virus — most sexually active people are infected at some point in their lives. There are more than 100 types of HPV, but only a few cause cervical cancer. Types 16 and 18 are responsible for about 70 percent of cervical cancers worldwide. These are called high-risk types because they can cause lasting cell changes.

When HPV infects the cervix, it can cause the cells there to change. In most cases, the immune system clears the infection and the cells return to normal. But if the infection persists — which happens in about 5 to 10 percent of people infected with high-risk HPV — the virus can cause cells to become abnormal. These abnormal cells are called precancerous or dysplastic. Over time, if these changes are not treated, they can develop into invasive cancer.

This process usually takes many years, often 10 or more. That slow progression is why screening works: finding and treating precancerous changes stops cancer from developing in the first place.

Stages of cervical cell changes before cancer develops

Doctors describe precancerous cervical changes using a grading system. Cervical intraepithelial neoplasia (CIN) is the medical term for these abnormal cells. CIN is divided into three grades based on how much of the cervix is affected and how abnormal the cells look under a microscope.

CIN1 (grade 1) involves mild changes in the cells. Many CIN1 cases clear on their own without treatment, though some progress. CIN2 and CIN3 (grades 2 and 3) involve more extensive abnormal changes and are more likely to progress to cancer if left untreated. CIN3 is considered a precancerous condition that should be treated. Treatment at any of these stages — usually a procedure to remove the abnormal tissue — prevents cancer from developing.

Another term you may see is squamous intraepithelial lesion (SIL), which is used interchangeably with CIN in some settings. Low-grade SIL corresponds to CIN1, and high-grade SIL corresponds to CIN2 and CIN3.

Risk factors that increase the chance of cervical cancer

Persistent HPV infection is the main risk factor, but other factors influence whether someone infected with HPV will develop cervical cancer. A weakened immune system — from HIV, organ transplant, or certain medications — makes it harder for the body to clear HPV infection. Smoking damages the immune cells in the cervix and increases the risk that precancerous changes will progress to cancer.

Long-term use of hormonal birth control (five years or more) is associated with a slightly higher risk, though the risk decreases after stopping. Having many sexual partners or starting sexual activity at a young age increases HPV exposure. Giving birth to many children may also increase risk, though the reason is not fully understood. Having a partner whose previous partner had cervical cancer is associated with higher HPV exposure.

Having risk factors does not mean someone will develop cervical cancer. Many people with multiple risk factors never do. Screening and prevention through vaccination are the most effective ways to reduce risk regardless of other factors.

Symptoms and when they appear

Precancerous changes and early cervical cancer usually cause no symptoms. That is why screening is so important — it finds changes before a person feels anything wrong. By the time symptoms appear, cancer has usually advanced beyond the earliest stages.

Symptoms of more advanced cervical cancer include abnormal vaginal bleeding (between periods, after sex, or after menopause), unusual vaginal discharge that may be watery or bloody, pelvic pain, or pain during sex. These symptoms can have other causes, but they should be evaluated by a doctor. If cervical cancer spreads beyond the cervix, symptoms may include back or leg pain, loss of bladder or bowel control, or fatigue.

How screening finds cervical cancer early

The Pap test (Papanicolaou test) collects cells from the cervix and checks them under a microscope for abnormal changes. The HPV test checks for the presence of high-risk HPV types. Both tests are done during a pelvic exam and take only a few minutes. Screening guidelines vary by age and previous test results, but most organizations recommend starting at age 21 and continuing at regular intervals.

Pap tests can detect precancerous changes and early cancer. HPV tests are more sensitive for detecting high-risk virus but less specific — a positive result does not mean cancer is present, only that the virus is. Many screening programs now use HPV testing first, with a Pap test only if HPV is found. This approach catches more cases of precancerous change while reducing unnecessary follow-up testing.

If screening finds abnormal cells, further testing with colposcopy — a magnified view of the cervix — helps determine whether treatment is needed. A small tissue sample (biopsy) may be taken to confirm the diagnosis.

Prevention through HPV vaccination

The HPV vaccine prevents infection with the virus types most likely to cause cervical cancer. Current vaccines protect against HPV types 16 and 18, which cause most cervical cancers. Some newer vaccines protect against additional HPV types. The vaccine is most effective when given before a person becomes sexually active, but it can still provide protection if given later.

The vaccine is recommended for people ages 11 to 26, though it can be given to older adults. It requires two or three doses depending on age at first dose and the specific vaccine used. The vaccine does not treat existing HPV infection, so it works best as prevention. People who have already been infected with one HPV type can still benefit from protection against other types covered by the vaccine.

Frequently Asked Questions

Can you get cervical cancer without HPV?

Rarely. HPV causes about 99 percent of cervical cancers. A very small number of cervical cancers are not linked to HPV, but these are uncommon. If you have cervical cancer and HPV testing is negative, your doctor will discuss what that means for your specific situation.

Does having HPV mean you will definitely get cervical cancer?

No. Most people infected with HPV clear the infection on their own and never develop cancer. Only persistent infection with high-risk types can lead to cancer, and even then it takes years and requires that precancerous changes go undetected and untreated.

Can men get cervical cancer?

No, because men do not have a cervix. However, men can be infected with HPV and can transmit it to partners. HPV in men can cause other cancers, including throat and anal cancer, though these are less common than cervical cancer in women.

Is cervical cancer hereditary?

Cervical cancer itself is not inherited, but some genetic factors may affect how the immune system responds to HPV infection. The main risk factor is HPV exposure, not family history. Having a family member with cervical cancer does not increase your risk unless you share the same HPV exposure.

What happens if cervical cancer is found early?

Early cervical cancer and precancerous changes are highly treatable. Treatment may involve removing the abnormal tissue through procedures like loop electrosurgical excision or cold knife conization. Survival rates are much higher when cancer is caught at early stages through screening than when it is found after symptoms appear.