0
0
Cervical cancer ranks as the fourth most common cancer in women globally and is the third leading cause of cancer-related deaths among women. In 2022, approximately 660,000 new cases and 350,000 deaths were reported worldwide. In Sweden, 450-550 new cases are diagnosed annually, with incidence rates remaining stable since the 1980s.
A new thesis from the Department of Medical Epidemiology and Biostatistics at Karolinska Institutet by PhD student and MD Hanna Milerad investigates clinical research questions on primary (HPV vaccination) and secondary (HPV-based cervical screening) prevention of cervical and vaginal cancer. The study focuses on four groups of women in the organized cervical screening program: those entering the screening program, those exiting it, non-attenders, and women previously treated for precancerous lesions. These groups correspond to different stages in the cervical cancer screening chain: 1) primary screening, 2) colposcopic examination, 3) treatment, and 4) follow-up after treatment.
Key Findings from the Thesis
Women Entering the Screening Program (Age 23)
- HPV-vaccinated women had a significantly lower prevalence of the most oncogenic types of HPV (HPV 16/18) at 5% compared to 33% in unvaccinated women.
- Colposcopy was effective even in vaccinated women entering the screening program.
Women Exiting the Screening Program (Ages 56-64)
- Among women re-tested for HPV after one year, 52% remained HPV positive, and 40% after three years.
- HPV testing could detect precancerous lesions in women exiting the program, though it demands more from colposcopists.
Non-attenders (Ages 33-62)
- HPV self-sampling kits were sent to women who hadn’t been screened in 10 years, with a 20% response rate and 15% testing positive for HPV.
- A significant number of these women had precancerous lesions or cervical cancer, indicating the feasibility of an opt-out strategy with HPV self-sampling and direct referral to colposcopy.
Women Previously Treated for Precancerous Lesions
- Between 1999-2018, 67,693 women were identified, and 213 developed cervical or vaginal cancer.
- There was a notably higher risk for invasive cancer within the first three years post-treatment.
Summary of Preventative Measures
Primary prevention through HPV vaccination and secondary prevention via HPV-based screening, along with high-quality processes throughout the cervical cancer screening chain, are crucial in preventing cervical cancer. These strategies enable early detection and significantly reduce mortality rates.
Personal Motivation
“I am a gynecologist and I see women with precancerous lesions and cervical cancer daily in the hospital, which got me engaged in the topic. It is fascinating that this type of cancer can not only be prevented (by vaccination and screening), but also eliminated as a public health problem.”
Future Research Directions
“In my mind, two of the most important future challenges are:
- Reaching non-attenders in screening and vaccination programs.
- Assessing women still at risk for cervical and vaginal cancer despite these preventative measures.
To address these challenges, more evidence is needed, but equally important is taking action. I believe study designs that allow for quality control while implementing new strategies might be the way forward.”
