Cervical Cancer Screening

Cervical cancer screening is a structured, population-based programme. It aims to identify and treat precancerous cervical abnormalities before progression to invasive malignancy, or to detect invasive cervical cancer at an earlier, more treatable stage.

Contemporary programmes are increasingly built around primary human papillomavirus testing, rather than the historical cytology-based approach. This reflects the well established causal relationship between persistent high-risk human papillomavirus infection and cervical intraepithelial neoplasia and, invasive cervical cancer.

It is one of the most successful cancer screening and prevention programmes in contemporary practice. Systematic screening combined with prophylactic human papillomavirus vaccination has substantially reduced cervical cancer incidence and mortality.

Screening methodology and natural history

• Persistent infection with high-risk human papillomavirus subtypes is the necessary causal factor in the great majority of cervical cancers. Types 16 and 18 together account for the majority of cases, alongside several other high-risk subtypes.
• The great majority of human papillomavirus infections are cleared spontaneously by the host immune system without lasting cervical abnormality. It is persistent, not transient, infection that carries the oncogenic risk.
• Primary human papillomavirus testing is increasingly the preferred primary screening approach. It is more sensitive than cytology alone for detecting the underlying infection.
• A negative human papillomavirus test is substantially reassuring and supports a longer interval before the next screening test. Clinically significant cervical abnormality is very unlikely to develop in the near term without detectable high-risk infection.
• When primary human papillomavirus testing is positive, reflex cytology of the same sample is generally performed. It supports triage and risk stratification: referral for colposcopic assessment, or continued closer interval surveillance, according to the result pattern.
• Cervical intraepithelial neoplasia, the histological precursor lesion identified by colposcopic biopsy, is graded by severity (generally CIN 1, 2, and 3). Increasing grade reflects increasing epithelial abnormality and increasing risk of progression to invasive malignancy if untreated.
• The grade directly informs management.

• Screening is offered to asymptomatic women within a defined age range. The starting and concluding ages and the screening interval vary somewhat by national or regional protocol, reflecting the epidemiology of human papillomavirus acquisition and cervical cancer risk across the reproductive and later lifespan.
• The screening process involves collecting a cervical sample by speculum examination. It is generally well tolerated, but many women feel anxiety or discomfort. A sensitive, professional and reassuring approach is important.
• Any woman with symptoms potentially suggesting cervical pathology (including postcoital bleeding, intermenstrual bleeding or abnormal vaginal discharge) needs symptom-directed clinical assessment, not reliance on routine screening alone.
• Screening is designed for asymptomatic women. A normal, recent screening result does not remove the need for prompt evaluation of a new, concerning symptom.
• Barriers to screening include embarrassment, anxiety, cultural or religious factors, and practical access barriers. They deserve proactive, sensitive attention.
• A substantial number of cervical cancers occur in under-screened or never-screened women. Improving engagement is an ongoing public health and clinical priority.

• Human papillomavirus testing on a cervical sample is the primary, standard screening test in contemporary practice. A positive result for high-risk subtypes prompts reflex cytological assessment of the same sample to guide management.
• Cytology characterises any cellular abnormality. It is the primary test in programmes still using the historical approach, and reflex triage after a positive primary human papillomavirus result elsewhere.
• Results are reported by a standardised classification system, ranging from normal to varying grades of dyskaryosis or atypia.
• The result directs the recommendation: continued routine screening, closer interval surveillance, or referral for colposcopic assessment.
• Colposcopy is direct, magnified visual examination of the cervix, with biopsy of any visually abnormal area. It is the essential diagnostic investigation for women whose screening result indicates sufficient risk.
• Biopsy provides definitive histological characterisation and grading of any cervical intraepithelial neoplasia.

• Women with a negative primary human papillomavirus test return to routine, standard-interval screening. The near-term risk of clinically significant cervical abnormality is near-negligible without detectable high-risk infection.
• Women with a positive human papillomavirus result but normal or low-grade reflex cytology are generally managed with a repeat test at a shorter, defined interval (commonly twelve months). Spontaneous clearance is substantially likely over this period, so immediate colposcopic referral is not required.
• Persistent positivity at the repeat test generally prompts referral for colposcopic assessment.
• Women with a positive human papillomavirus result and higher-grade reflex cytological abnormality are referred for colposcopic assessment. The grade of any confirmed cervical intraepithelial neoplasia on biopsy then directs management.
• Lower-grade abnormality (CIN 1) is frequently managed with continued surveillance alone, given the substantial likelihood of spontaneous regression.
• Higher-grade abnormality (CIN 2 or 3) generally warrants treatment, most commonly by large loop excision of the transformation zone. This is a relatively minor, outpatient procedure that removes the affected area of the cervix for both treatment and further histological assessment.
• After treatment of confirmed cervical intraepithelial neoplasia, structured follow-up testing is performed at a defined interval. This "test of cure" combines human papillomavirus and cytology assessment to confirm successful treatment and clearance of high-risk human papillomavirus.
• The result directs return to routine screening or continued enhanced surveillance.
• Proactive engagement strategies to improve uptake among under-screened populations, and continued promotion of prophylactic human papillomavirus vaccination, underpin population-level cervical cancer prevention alongside the individual screening and management pathway. Vaccination is a complementary primary prevention strategy that reduces the burden of relevant human papillomavirus infection in the population.