A well woman attends for cervical screening advice. Based on the long natural history of cervical carcinogenesis, what is the appropriate routine screening interval for a woman with normal smears?

Answer: E. Every 3 to 5 years

Cervical screening interval

The progression from HPV infection through CIN to invasive cancer is slow (months to years to over 20 years). This long lag phase means that screening every 3-5 years is sufficient to detect and treat pre-invasive disease before it becomes cancer.

Screening principles

• Cervical cancer is highly preventable with regular screening because CIN (LSIL/HSIL) can be detected on a smear and effectively treated.
• Screening starts once a woman has begun having intercourse and continues until about 65 years.
• A cytobrush (with a spatula) is used to sample the endocervix, especially in postmenopausal women in whom the transformation zone ascends into the canal.
• HPV DNA testing is also used for screening.

Why the other intervals are wrong

Monthly, six-monthly or annual lifelong screening is unnecessarily frequent given the slow natural history; once-in-a-lifetime screening would miss disease that develops later. The 3-5 year interval matches the biology.