"I never missed a single cervical cancer screening that comes around every two years. But one day, I started bleeding outside my menstrual period, then felt a heavy pulling sensation in my lower abdomen and even developed back pain."
Seo, a 45-year-old working mother with elementary school-aged children, had diligently undergone the government-funded Pap smear every cycle since she turned 20. Though somewhat cumbersome, receiving results that read "no abnormalities" always brought her peace of mind. She occasionally experienced vaginal bleeding unrelated to her menstrual cycle but dismissed it as a temporary symptom. It was only after she developed pain during urination and discovered blood in her urine that she visited a hospital. Seo was diagnosed with stage 4 cervical cancer. The normal findings she had trusted for decades turned out to be "false negatives" — results that failed to detect cancer cells that were already present.
Cervical cancer is a female reproductive cancer that develops in the cervix, the opening of the uterus. According to the Korea Central Cancer Registry, cervical cancer accounted for 1.1% (3,144 cases) of the 288,613 new cancer cases diagnosed in South Korea in 2023. Compared to 2001, when 4,655 patients were diagnosed and the disease ranked sixth in incidence after stomach, lung, liver, colorectal, and breast cancers, the incidence rate has dropped sharply over two decades. As of 2023, cervical cancer ranks 17th in overall cancer incidence for both sexes combined, and 11th when limited to women. By age group, women in their 40s accounted for the largest share at 22.8%, followed closely by those in their 50s (22.6%) and 60s (19.1%). The biggest factors behind the decline are the national cancer screening program launched in 2002 and the human papillomavirus (HPV) vaccine, which was included in the National Immunization Program (NIP) in 2016.
More than 99% of cervical cancer cases are caused by HPV infection. Given that the causes of most cancers remain unclear, cervical cancer is more akin to infectious diseases such as plague or measles. Thanks to this characteristic, a vaccine has been developed, and the prognosis is favorable when the disease is detected early through screening. According to the Korea Central Cancer Registry under the Ministry of Health and Welfare, the five-year relative survival rate is 94.5% when the cancer is confined to the cervix and has not spread to other areas — far higher than lung cancer (81.5%), liver cancer (63.5%), and pancreatic cancer (47.8%). The problem is that heartbreaking cases like Seo's, where patients miss the golden window despite faithful screening attendance, continue to occur. This stems from a fundamental limitation: the sensitivity of the Pap smear, which is provided free of charge to women aged 20 and older, is only about 50–70%. With a 30–50% probability of a lesion being classified as normal, opportunities for early cancer detection are easily missed. Multiple studies have shown that approximately 30–50% of cervical cancer patients had Pap results reported as normal three to five years before diagnosis. Lee Jae-kwan, chairman of the Korean Society of Obstetrics and Gynecology and professor of obstetrics and gynecology at Korea University Guro Hospital, said, "There are many cases where patients rely on normal results from regular national screenings, only for their diagnosis to be delayed by one or two stages." He added, "Under a Pap-only system, some patients are structurally bound to be missed." Making matters worse, the screening participation rate remains around the low 60% range, leaving a wide blind spot.
It takes years to decades for normal epithelial cells of the cervix to progress through cervical intraepithelial neoplasia to invasive cervical cancer after HPV infection. Detecting precancerous lesions as early as possible is the key to cervical cancer prevention. HPV DNA testing can identify abnormal cells with the potential to develop into cancer at an earlier stage, advancing the timing of treatment. "While the Pap smear observes cells that have already undergone changes as an outcome, HPV testing detects the cancer-causing virus at the causal stage first," Lee said. "With a sensitivity of over 90%, it is far more precise than cytology testing, and the probability of missing abnormal lesions is significantly lower." The World Health Organization (WHO) recommended in 2021 that HPV DNA testing replace the Pap smear as the primary screening method for women aged 40 and older. Australia, the United Kingdom, and the Netherlands have adopted HPV-first testing as the national standard, while the United States and other countries operate HPV-only or Pap co-testing strategies. "In Korea, precancerous lesions are increasing among women in their 20s and 30s, and screening participation rates are relatively low, making changes to the national screening system necessary," Lee said. "If HPV testing is fully introduced, stage distribution will shift earlier, increasing the number of patients who can choose uterus-preserving surgery or minimally invasive treatment, and reducing the proportion of radiation and chemotherapy — which can be a great help in preserving patients' fertility and quality of life." Although the unit cost of HPV testing is higher than the conventional Pap smear, the long-term reduction in cervical cancer incidence and treatment — and the resulting savings in medical and social costs — could actually benefit the national budget. Even if Pap results are normal, women who are sexually active or belong to high-risk groups due to smoking or immunosuppression may want to consult a specialist about receiving an additional HPV test.
Alongside improvements to the screening system, experts emphasize expanding HPV vaccination as another critical pillar in the fight against cervical cancer. HPV causes not only cervical cancer but also head and neck cancer, anal cancer, oropharyngeal cancer, and various other diseases. Because it is transmitted through mucosal contact, anyone — male or female — can become infected. In that regard, the government's decision to begin HPV vaccine support for 12-year-old boys starting this year is considered a meaningful first step. However, many have expressed disappointment that the program is limited to the quadrivalent vaccine, which protects against only four HPV types including types 16 and 18. "Introducing the 9-valent vaccine and expanding the vaccination target population is an investment that will fundamentally lower cancer incidence and medical cost burdens 20 to 30 years from now," Lee said. "In the medium to long term, strategies must be developed sequentially — introducing the 9-valent vaccine into the national immunization program, expanding the eligible age range, and establishing catch-up vaccination programs for unvaccinated individuals who missed their initial window."
