Why is cervical screening missing in so many countries?
Cervical cancer is almost always caused by a virus, the human papillomavirus (HPV). It can be prevented by vaccination and screening, which finds precancer, meaning abnormal cells that could turn into cancer.
But according to the authors, vaccination and screening are lacking in most lower-resource settings, where about 80% of more than 500,000 yearly cases occur. There, health workers often look at the cervix after applying vinegar (acetic acid). It is practical but not reliable: two people do not always see the same thing.
What did the researchers do?
The team used data from a large study of 9,406 women aged 18 to 94 in Guanacaste, Costa Rica. They were followed for 7 years, from 1993 to 2000, with several screening methods and microscope checks of any lesions. A cancer registry identified cancers up to 18 years later.
During screening, photos of the cervix had been taken with a fixed-focus camera. The researchers digitized these photos and trained a deep learning algorithm, a type of AI that learns from examples, to recognize precancer and cancer automatically.
The AI read photos better than people and the smear test
To measure accuracy, the researchers used the area under the curve (AUC): 1 is a perfect test, 0.5 is chance. On photos taken when women joined the study, the AI scored 0.91. The original human reading of the same photos scored 0.69, and the standard smear test (cytology) 0.71.
In a scenario where women aged 25 to 49 have a single round of visual screening, the AI would find 127 of the 228 precancers diagnosed in the whole adult population, or 55.7%, while referring only 11% of women for further care.
Key figures
- 0.91area under the curve for the AI, against 0.69 for human reading of the photos and 0.71 for the smear test
- 9,406women followed for 7 years in Costa Rica
- 55.7%of precancers found in one screening round in women aged 25 to 49, while referring 11% of women
Keeping your cervical screening on track with Mima
This AI is mainly aimed at countries where smear tests are lacking, and it still needs testing with recent cameras. Where you live, the smear or HPV test remains the recommended screening, at regular intervals.
Mima helps you keep the date of your last screening and its results, so the next one does not slip by. You can also note a question for your next appointment: "When is my next HPV test or smear due?"
What this could change for women
If the method works with today's digital cameras, screening could be done in one visit, on the spot, without a laboratory. The authors call this point-of-care screening: the photo is read straight away, and a woman can be referred without waiting weeks for a result.
In countries where smear tests and HPV tests are rare, this could reach many more women.
What are the limits of this study?
The photos date from the 1990s and were taken with an old camera. The authors stress that results must now be checked with current digital cameras. The study is observational: the AI read past images and was not used to decide anyone's care.
The data come from a single region of Costa Rica. The AI will need testing in other countries and settings before we know whether it truly helps reduce cancers.
Frequently asked questions
Can AI screen for cervical cancer from a photo?
In this study, an AI spotted precancer on photos of the cervix better than human reading and the smear test. It still needs to be validated with current cameras.
Does this AI replace the smear test or HPV test?
No. It is mainly meant for countries where smear and HPV tests are rare. Where they exist, they remain the recommended screening.
What is cervical precancer?
It is a change in the cells of the cervix that is not cancer yet but could become cancer. Finding it means it can be treated first.
Why use old photos?
Because these women were followed for years, so researchers know who developed a lesion. That is what makes it possible to train and test the AI.
The original study
Hu L, Bell D, Antani S, et al. “An Observational Study of Deep Learning and Automated Evaluation of Cervical Images for Cancer Screening” Journal of the National Cancer Institute, September 1, 2019. DOI : 10.1093/jnci/djy225
Read the full study in the Journal of the National Cancer InstituteThis article summarizes a scientific study and is not medical advice.