When a woman has a smear test, two types of cell are sampled – squamous cells from the ectocervix, and glandular cells from the endocervix:
When abnormal cells are found they are mostly squamous cells from the ectocervix. But about one time in twenty they are glandular cells from the endo-cervix. The squamous cells, meanwhile, can have either a high-grade or a low-grade abnormality.
A recent Swedish study followed up over three million women who had had a cervical smear. Over 15 years, over 3% of women with high-grade squamous cell abnormality and nearly 1% with low-grade squamous cells abnormality developed invasive cancer – almost always squamous cell cancer. But what about the much smaller population of women with abnormal glandular cells? Here about 2.5% developed cancer over the follow-up period – usually adenocarcinoma. The risk is greatest over the first few months, thereafter accumulating very gradually. The high risk post-smear is, of course, because the smear is the trigger for the biopsy. The very slow progression rate over subsequent years should be highly reassuring for any woman who has had an abnormal smear result. As cone biopsy is associated with worse pregnancy outcomes, the CLAHRC WM Director would advise women with abnormal glandular cells to have regular smear test and complete their families as soon as possible. Testing for different types of papilloma virus may help determine whether the risk is higher or lower than the above risk of 2.5%. This study shows the value of long-term registry data of the sort Sweden is famous for.
— Richard Lilford, CLAHRC WM Director
- Wang J, Andrae B, Sundström K, et al. Risk of invasive cervical cancer after atypical glandular cells in cervical screening: nationwide cohort study. BMJ. 2016; 352: i276.