Cervical Screening FAQs for Healthcare Providers

A large majority of cervical cancer is due to the human papillomavirus.

Human papillomavirus (HPV) is a family of common viruses. There are more than 100 types of HPV and some types are oncogenic (cancer-causing). Currently, about 13 types of HPV are known to be oncogenic including types 16 and 18. These types of HPV can lead to cervical cancer over several years.

HPV is passed from one person to another through sexual activity. Sexual activity includes sex and touching another person’s genitals with the hand or mouth. HPV infections are common and up to 80 percent of sexually active people will have at least one HPV infection in their lifetime.

HPV infections can cause abnormal cell changes in the cervix. If left untreated, these cell changes can lead to cervical cancer over several years. Most HPV infections go away on their own without causing any harm. It is not well-understood why some HPV infections go away and some do not. For people who are immune competent, it typically takes 15 to 20 years for HPV to lead to cervical cancer. Only abnormal cell changes that are caused by oncogenic types of HPV can lead to cervical cancer.

Risk Factors for Acquiring HPV Infection

• Number of sexual partners
• Number of sexual partners that partner has had

Co-Factors Associated with Cervical Cancer that May or May Not Be Causal

• Smoking tobacco and exposure to second-hand smoke
• Immunosuppression (e.g., HIV, organ transplant, immunosuppressive drug therapy or chemotherapy)
• More than 5 full-term pregnancies
• Other sexually transmitted infections

Benefits

• Cervical cancer is almost entirely preventable with regular screening, appropriate follow-up of results and the human papillomavirus (HPV) immunization.
• Screening significantly reduces cervical cancer incidence (i.e., new cancer cases) and mortality (i.e., deaths).
• Regular screening can help lower the risk of getting cervical cancer.

Potential Limitations

• Cytology tests are not perfect and may miss some abnormal cells that could lead to cancer over several years (i.e., pre-cancers).
• Some abnormal cell changes can develop in the time between screens, which is why it is important for most eligible people to get cervical screening every three years.
• Cytology test results can sometimes be abnormal, but when someone has more follow-up (e.g., colposcopy), it might show that there is no pre-cancer or cancer. This is called a “false-positive.”
  • A cytology test can be abnormal for many reasons, including reasons that are not related to cervical cancer.
  • A false-positive cytology test result can lead to harms, such as worry and anxiety, and additional tests and treatments that are not needed.
  • Harms of treatment include anxiety, discomfort and in some cases, problems with future pregnancies.
• Not all abnormal cells that are found through cervical screening will become cancer. Therefore, some people may have additional testing or treatment for a condition that would have never been life-threatening. This is called “over-diagnosis”.
• A cytology test result can occasionally be normal even though there are abnormal cell changes. This is called a “false-negative.”
  • A false-negative cytology test result might delay diagnosing cell changes in the cervix that could lead to cervical cancer over several years (pre-cancerous changes).
  • Because it can take many years for pre-cancer to turn into cancer, the Ontario Cervical Screening Program recommends screening every three years for most people to help reduce the risk of delayed diagnosis.

The Ontario Cervical Screening Program does not recommend cervical screening for patients under the age of 21 regardless of risk factors.

• Current Ontario Cervical Screening Program recommendations state that people should begin cervical screening at age 21 if they are or have ever been sexually active.
• Until the change is formally implemented, we encourage primary care providers to consider delaying screening until age 25 except for people who are immunocompromised.
• The OCSP will formally change the age of initiation for cervical screening from 21 to 25 with the implementation of human papillomavirus (HPV) testing in the program except for people who are immunocompromised.
• For details see Cervical Screening at Age 25.

The 3-year screening interval is consistent with knowledge about the natural history of cervical cancer. There is no evidence that annual screening is superior to screening every 3 years. There is evidence that more frequent screening increases harms without significantly increasing benefits (see What are the benefits and potential limitations of screening?).

Screening Every 3 Years Is Safe and Effective

• Pre-malignant changes in the cervix develop slowly, usually over many years, before cervical cancer develops.
• Cervical changes that are clinically significant can be detected through regular screening every 3 years.
• If these abnormalities do not resolve on their own, they can be treated so that cervical cancer is prevented.

The recommendation for a 3-year screening interval was based on solid evidence showing that screening every 3 years is safe and effective.

Ontario Health (Cancer Care Ontario) is encouraging primary care providers to start cervical screening at age 25 based on moderate quality evidence suggesting that people under age 25 do not benefit from cervical screening. For details, see Cervical Screening at Age 25.

• Screening should be continued in people with a cervix over age 70 if they have not had 3 or more negative Pap tests in the previous 10 years.
• There is no evidence to suggest that continuing to screen people with a cervix over age 70 who acquires new partners is beneficial if they have an adequate negative screen history in the 10 years prior to age 70.

Certain populations benefit from more frequent screening than the average risk population. Annual cervical cytology screening for people with a cervix age 21 or older is advised for:

• people with a cervix who are immunocompromised (see How frequently should I screen my patients who are immunocompromised?)
• people with a cervix who have previously been treated in colposcopy and discharged to primary care with either an HPV positive result or an ASCUS/LSIL cytology (see How frequently should I screen my patients who have had a colposcopy and have been discharged back into primary care?)

People who are immunocompromised (e.g., people who have human immunodeficiency virus [HIV] or are on long-term immunosuppressants) should get screened once a year.

The Ontario Cervical Screening Program defines immunocompromised populations needing annual cervical screening as those belonging to the following groups:

• People who are living with human immunodeficiency virus (HIV)/acquired immunodeficiency syndrome (AIDS)
• People requiring long-term treatment (either continuously or at frequent intervals) with medications that cause immune suppression
• Organ transplant recipients (solid organ transplant or allogeneic stem cell transplants)
• People who are living with systemic lupus erythematosus, regardless of whether they are receiving immunosuppressant treatment
• People with congenital (primary) immunodeficiency

The colposcopist and patient discharge letter are the best sources of guidance for specific recommendations regarding individual patients. However, in general, the following recommendations apply:

For patients who were discharged from colposcopy with an HPV test (where available):

• If your patient was discharged from colposcopy with a negative HPV test result, they are considered to be at low risk for cervical cancer and should return to routine screening with cytology (every 3 for most people).
• If your patient was discharged from colposcopy with a positive HPV test result, they are considered at elevated risk for cervical cancer and should be screened with cytology annually.

For patients who were discharged from colposcopy where HPV status is unknown:

• If your patient was discharged from colposcopy with multiple normal or negative for intraepithelial lesion or malignancy (NILM) cytology results, they are considered to be at low risk for cervical cancer and should return to routine screening with cytology (every 3 years for most people).
• If your patient was discharged from colposcopy with a combination of atypical squamous cells of undetermined significance (ASCUS), low grade squamous intraepithelial lesion (LSIL) and/or normal cytology in their last 3 colposcopy results, they are considered to be at elevated risk for cervical cancer, and they should be screened with cytology annually.

A patient can resume screening every 3 years when they have a negative HPV test result or, in the absence of HPV testing, has 3 consecutive normal yearly cytology results.

In these cases, the patients’ risk of high-grade squamous intraepithelial lesion (HSIL) or cervical cancer returns to the risk level of the general population or lower.

Many people discharged from colposcopy return to a routine screening interval (screening every 3 years). These people should be referred to colposcopy based on Ontario Cervical Screening Program guidance. However, people at elevated risk of cervical cancer being screened annually need to be re-referred to colposcopy based on Ontario Cervical Screening Program guidance.

For patients being screened with cytology every 3 years

Refer to colposcopy when your patient has two consecutive atypical squamous cells of undetermined significance (ASCUS) results, two consecutive low-grade squamous epithelial lesion (LSIL) results, high-grade squamous epithelial lesion (HSIL) cytology, atypical squamous cells, cannot rule out high-grade (ASC-H) cytology, atypical glandular cells (AGC-NOS, AGC-N) cytology or adenocarcinoma in-situ (AIS) cytology.

First time LSIL results can be managed in primary care with repeat cytology in 12 months. If the repeat test result is abnormal, the person should be referred to colposcopy.

For patients being screened with cytology every year

Re-refer to colposcopy with any abnormal cytology result.

Atrophy is a normal clinical state that does not increase the risk of high grade dysplasia or cervical cancer. It requires action only if clinically indicated (e.g., for vaginal symptoms or for re-evaluation of cytology).

Benign endometrial cells can be found on routine cervical cytology. They are most often a routine finding that does not require any action.

• Pre-menopausal patients who are asymptomatic require no action (continue to follow usual screening recommendations).
• Post-menopausal patients require investigations, including imaging or endometrial tissue sampling.
• Any patient with abnormal vaginal bleeding requires appropriate investigation.

• Absence of transformation zone (T-zone) components alone does not require earlier re-screening.
• Patients whose cervical cytology is satisfactory for evaluation and negative for intraepithelial lesion or malignancy (NILM) but T-zone components are lacking, should be re-tested at their regular screening interval as per the recommendations for follow-up of abnormal cytology
• Patients with abnormal cervical cytology should follow the screening recommendations regardless of the presence or absence of T-zone components.

• The recommendation for screening average-risk patients every 3 years was based on evidence showing that a 3-year screening interval is safe and effective. See What does the evidence say about triennial (every 3 years) screening vs. annual screening?.
• There is no evidence that annual screening for average-risk patients is better than screening every 3 years. There is evidence that it is harmful to screen patients more often than every 3 years.
  • Potential harms of screening include the chance of false positive results, the chance of overtreatment, the chance of false negative results, and discomfort, pain, inconvenience, or embarrassment associated with a Pap test.
• Getting screened more often than recommended will not give extra protection against cervical cancer.
• Some patients have special circumstances (i.e., some people discharged from colposcopy and people who are immunocompromised) that require annual screening. See Under what circumstances should I screen patients more frequently than what is recommended in the guidelines?

• HPV testing should only be considered as a triage following an atypical squamous cells of undetermined significance (ASCUS) cytology result for women who are age 30 and older.
• Cancer Care Ontario is working with the Ontario Ministry of Health and Long-Term Care (MOHLTC) to explore the role of funded HPV testing in the Ontario Cervical Screening Program (OCSP).
• At this time, the HPV test is not funded by the MOHLTC. It is available from community labs on a user-pay basis for a cost of about $90 to $100 per test. Because this test is not publicly funded and patients have to pay for it, most women do not have access to this test. An appropriate alternative following an ASCUS cytology result is to repeat the Pap test in 6 months.

View or download these resources from Cancer Care Ontario to share with your patients:

• Pap test brochure – Take a Closer Look
• Cervical Cancer Screening – What your abnormal Pap test means
• Cervical Screening FAQs

Visit The Society of Gynecologic Oncology of Canada website where you can access brochures and other resources.

No, cost was not a consideration in the development of the screening guidelines. The recommendations were developed based on scientific evidence that balances the benefits of screening with the associated potential limitations.

• Cancer Care Ontario’s guidelines were developed by an expert panel based on a rigorous systematic review and meta-analysis of high-quality evidence conducted by Cancer Care Ontario’s Program in Evidence-Based Care (PEBC).
• There is no evidence that annual screening is superior to screening every 3 years. There is evidence that more frequent screening increases harms without increasing benefits. See What are the benefits and potential limitations of screening?.
• The 3-year screening interval is consistent with knowledge about the natural history of cervical cancer.
• Most Canadian jurisdictions do not screen women annually. Worldwide, several organized programs comparable to Ontario’s screen every 5 years. Moreover, some jurisdictions initiate screening women for cervical cancer at age 21 and many recommend initiation at an even older age (e.g., 25). No organized screening program recommends initiation of screening earlier than age 21.