Cervical cancer screening: Clinical sciences

Cervical cancer screening is a preventive procedure that evaluates asymptomatic patients for cervical abnormalities, especially high-grade precancerous cells, or dysplasia, and invasive cervical cancer. Screening decreases cervical cancer incidence and mortality rates and is associated with higher cure rates for invasive cervical cancer due to timely diagnosis.

Risk factors for cervical cancer include previous treatment of a high-grade precancerous lesion, HIV infection, and a compromised immune system. Additionally, high-risk HPV, or human papillomavirus, is associated with nearly all cases of cervical cancer. Guidelines for screening combine a patient’s current test results with their screening history to direct clinical decision-making, with consideration for the patient’s immunocompetence, presence of a cervix, and age.

Your first step in assessing a patient who presents for cervical cancer screening is to obtain a focused history and physical exam. Knowing which screening test to perform and how often to perform it depends on a number of factors, including patient age, previous screening interval, results of past screening and treatment if available, whether the patient has had a hysterectomy, and their immune status, specifically whether they are HIV positive or currently take immunosuppressive medications.Because cervical cancer screening is only appropriate for asymptomatic patients, the history should be negative for any abnormal uterine or vaginal bleeding. On the other hand, the physical exam includes a speculum examination to visualize the cervix, which should appear normal. If the patient has had a hysterectomy with removal of the cervix, inspect the vaginal cuff, which should appear normal as well.

Here’s a clinical pearl! Any grossly visible abnormal lesions on the cervix should have a targeted biopsy for assessment.

Your next step is to assess the patient’s immunocompetence. Most patients who undergo cervical cancer screening have a normally functioning immune system. For screening purposes, this means that your patient has a negative HIV status and does not currently take immunosuppressive medications for conditions such as inflammatory bowel disease, rheumatologic disease, organ transplant, or lupus. If your patient is immunocompetent, you should then assess whether the cervix is present.

Immunocompetent patients who have a cervix will undergo cervical cancer screening based on age. Initiate screening at the age of 21. Patients between the ages of 21 and 24 are considered to be a special population for screening because of their low risk of cervical cancer, even with a high rate of HPV infection. The recommended cervical cancer screening for this age group is cytology alone every 3 years to reduce false positives from the presence of a transient HPV infection.

Now the next age group, which is 25 to 65 years, is when most cervical abnormalities are identified. The first step for screening in this population is to calculate the patient’s immediate risk for having CIN3+, defined as cervical intraepithelial neoplasia 3 plus worse findings, such as adenocarcinoma in situ, or AIS, and invasive cervical cancer. The patient’s immediate risk of having CIN3+ is based on their previous screening tests and any biopsy results. You can calculate the risk level by using published tables or inputting the patient’s information into the available smartphone app or web application from the American Society for Colposcopy and Cervical Pathology, or ASCCP, website.

Here are a few high-yield facts! Let’s take a moment to distinguish between the SIL classification compared to the CIN classifications. SIL stands for squamous intraepithelial lesions, and refers to cytologic abnormalities, which are screening results. On the other hand, the CIN stands for cervical intraepithelial neoplasia, and refers to histological findings based on colposcopic biopsy results, and is considered diagnostic and prognostic. While the risk of CIN can be predicted based on the SIL designation, only the CIN histology result is diagnostic of the actual dysplasia present.

Now, CIN is a precancerous condition of the cervix that can be low grade, such as CIN1, or high grade, such as CIN2 or CIN3. CIN1 refers to atypical cellular changes in the lower one-third of the cervical epithelium. CIN2 represents moderately atypical cellular changes confined to the basal two-thirds of the epithelium, while CIN3 describes severely atypical cellular changes encompassing more than two-thirds of the epithelial thickness, including full-thickness lesions. Low-grade cervical lesions, or CIN1, are much less likely to progress to cervical cancer than high-grade lesions unless high-risk HPV is also present.

Patients with an immediate CIN3+ risk of less than 4% are then stratified based on their 5-year CIN3+ risk, which is also calculated using the ASCCP website or smartphone app. If the 5-year CIN3+ risk is less than 0.15%, the patient should undergo routine cervical cancer screening.