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Keys to Early Detection of Cervical Cancer and Precancer: Interview with Professor Koji Matsumoto on the Importance of Colposcopy and the Role of AI

Professor Koji Matsumoto

Department of Obstetrics and Gynecology, Showa University School of Medicine (Japan)

Colposcopy: An Effective Tool for Early Detection of Cervical Cancer and Precancer

We interviewed Professor Koji Matsumoto, of Showa University School of Medicine about the importance of colposcopy and the role of AI, asking for insights into his joint research with Casio on AI diagnostic support systems.

First, here is a brief explanation of colposcopy and the Casio COLPOCAMERA.

Colposcopy is a diagnostic procedure that involves using a medical device called a colposcope to magnify the view of the cervix after inserting a speculum into the vagina. When early lesions or cervical cancer are suspected, a biopsy (tissue sample) may also be performed, followed by microscopic examination of the sample by a pathologist to definitively diagnose the stage of the lesion.

Colposcopy is often performed as a secondary examination for women who have tested positive in a cervical cancer screening. The diagnostic results are classified into four steps in the development of cervical cancer: the first three, CIN1 (mild dysplasia), CIN2 (moderate dysplasia), and CIN3 (severe dysplasia/carcinoma in situ), are precursor lesions, while the fourth is invasive cancer.

Precursor lesions are conditions that may develop into invasive cancer if they persist and progress. Mild cases often regress to normal spontaneously, while the early treatment of high-grade precancerous lesions, such as CIN2 and CIN3, can effectively prevent cervical cancer.

The accuracy of the biopsy site selection significantly impacts the diagnosis. Increasing the number of biopsy sites places a greater burden on the patient. As such, selecting appropriate biopsy sites requires advanced skills.

During examinations and biopsies, it is crucial to carefully observe the cervix and maintain accurate records. However, capturing images of the cervix, which is located deep in the vagina, is challenging when using conventional digital cameras.

The Casio COLPOCAMERA allows practitioners to focus in on details by illuminating the cervix with its built-in LED lights. With a touch focus function on its LCD monitor, it is an optimal medical device for cervix observation and imaging well suited to clinical settings. The camera can take both still and video images. Still images can be captured in three types (normal/green/polarized) with a single touch of the shutter button. This allows for easy comparison of high- quality images with the same angle of view, all in a simple operation.

Colposcopy Proficiency: A Growing Need Among Doctors

—Why is there growing attention on mastering colposcopy?

Prof. Matsumoto: “Few doctors have received a formal, systematic education in performing colposcopies. In fact, there are currently no proper educational or training tools available, and guidelines do not provide detailed instructions. Many doctors learn by exchanging information with other doctors, imitating what they see, and then refining their skills through trial and error based on their own experiences.

While the colposcopy as a procedure is not a recent development, the increasing specialization within gynecologists has decreased the number of practitioners who are proficient in it.

Gynecologists specializing in oncology study colposcopy. Meanwhile obstetricians primarily focus on childbirth, so they have little opportunity to perform this type of procedures. They do not need to study it in-depth; even if they learned it during their residency, they tend to forget it over time.

Another issue is that many clinics refer patients in need of colposcopy to larger hospitals that deal with cancer, making it difficult to expand the base of practitioners.

In this context, Guidelines for Cervical Cancer Screening Based on Efficacy Evaluation were updated in 2020, reaffirming the effectiveness of HPV screening (using HPV detection tests for cervical screening) in cervical cancer prevention. More countries are now introducing HPV screening in place of cytology for cervical cancer screening.

HPV screening is more sensitive than cytology and has fewer false negatives. However, while it misses fewer cases, it also identifies as positive those who are infected with HPV but do not have lesions, leading to more false positives in cervical cancer screening. These results are then sorted using cytology. However, this triage is also challenging. As a result, we can expect that many HPV- positive individuals will be referred for colposcopy examinations.

Based on the results of clinical trials conducted outside of Japan, the number of people receiving colposcopy examinations in Japan can be predicted to roughly triple, while the detection of CIN2 and CIN3 will increase two to three times. This is a highly probable prediction. There is a severe shortage of doctors capable of performing colposcopy examinations, and the number of patients seeking colposcopy tests is expected to increase, even at obstetricians’ offices and clinics. This is the background behind the growing need for OB/GYNs to master colposcopy.”

—So, to prevent large cancer treatment hospitals from being overwhelmed, we need more doctors who can perform detailed examinations and diagnose and manage early lesions, correct?

Prof. Matsumoto: “As the number of people undergoing examinations increases, there will be a temporary uptick in patients found with precancerous lesions. This increase means we will detect cases that had previously been overlooked due to false negative results in cytology-based screening. Once we go through this phase, the number of cervical cancer patients will eventually decrease, because we will detect and treat high-grade precancerous lesions early, before they develop into cervical cancer.

Furthermore, as HPV vaccination becomes more widespread, HPV infections will eventually decrease, leading to fewer cases of cervical cancer. However, this process will take at least ten years in Japan and likely longer globally. Until then, this number will not reach zero, so there will always be a certain level of demand. Because HPV vaccines are quite expensive, the importance of colposcopy is likely to increase in developing countries where introducing HPV vaccines may be financially challenging.”

Prospects for AI Diagnostic Support Systems in Colposcopy

—Professor Matsumoto, could you share your thoughts on the prospects for AI diagnostic support systems in colposcopy?

Prof. Matsumoto: “Currently, I am collaborating with Casio to develop an AI diagnostic support system to assist in diagnosis during colposcopies. The Casio team is enthusiastic and dedicated to creating a product that can be released to the world. In our research meetings, I feel comfortable expressing my frank opinions without hesitation (laughs).

The AI will be taught using high-resolution images captured using the COLPOCAMERA to support colposcopic diagnosis. Ideally, the AI may ultimately be able to predict pathological diagnosis as well.

There are various beneficial ways to use AI in assisting colposcopy diagnosis, including improving the examination efficiency and preventing oversights. The AI diagnostic support system we are currently working on is approaching the goal we set as a first step, and we can see the path to completion. Once finished, I believe it will enable regular OB/GYNs, not just colposcopy experts, to diagnose as efficiently as experts.”

—Lastly, could you offer some advice for those who want to learn colposcopy?

Prof. Matsumoto: “As I mentioned earlier, there are currently no tools through which colposcopy can be systematically taught. Because of this, OB/GYNs are likely to be uncertain about whom to ask or which books to read to obtain the correct information. However, you absolutely cannot become proficient without practical experience. With an AI diagnostic support system, it will be possible to learn through practice. I expect that AI- assisted diagnosis support will also be instrumental as an educational and training tool.”

——Thank you very much.

Studies have shown that the incidence of cervical cancer could be significantly reduced through the implementation of cervical cancer screening and HPV vaccination programs. However, it will take decades before the effects of the HPV vaccine can be confirmed across a wide range of generations. Until then, the early detection and treatment of cervical precancer remains essential in the prevention of cervical cancer.