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Following the implementation of the National Cervical Screening Program (NCSP) renewal in December 2017, the recommended upper age to be eligible for screening increased from 69 years to 74 years.
Professor Yee Leung explains
Why was the change to exit at age 74 introduced?
Modelling, using the NCSP renewal pathway of partial genotyping human papillomavirus (HPV) screen with reflex liquid-based cytology (LBC), predicted an overall 24% reduction in cervical cancer cases and a 29% reduction in cervical cancer mortality in the vaccinated population.
From 1982 to 2019 the number of new cervical cancer cases annually has reduced to approximately 100 cases in the 70+ age cohort. Screening this cohort would detect additional cases of cervical cancer that would otherwise present at a late stage.
The average life expectancy of a young septuagenarian (aged 70–74) woman in Australia today is approximately 18 years. The increase in age to exit the screening program to 74 years was based on modelling that accounted for the increasing life expectancy of the young septuagenarian. Exit testing with HPV subtyping and reflex LBC was therefore recommended between the ages of 70–74 on the basis that the benefits of screening outweighed
the risks.
Are the young septuagenarians participating in the NCSP?
Progression towards five-year participation from 2018 to 2022 is 34.9% for participants aged 70–74. This compares to the 79.5% five-year participation in those aged 25–29. Coverage was also lowest at 38.9% for the aged 70–74 cohort who have a HPV or LBC test for any reason in 2018–2022. The aged 70–74 cohort are clearly not being screened.
What are the screening results for the young septuagenarian?
In 2022, the majority of primary screening test results in participants aged 70–74 was low risk (crude rate 94.3%), the remainder being intermediate risk (2.6%) and higher risk (2.2%) compared to results of all participants aged 25–74 at 89.4%, 7.5% and 2.3% respectively. For those with an intermediate result, 5.6% will be higher risk at first follow-up, comparable to 4.9% for eligible participants in the program.
The number of new cervical cancer cases in those aged 70+ constitute approximately 12% of all cases, indicating that from a screening program perspective, this cohort should not be ignored.
Are septuagenarians at higher risk of high-grade abnormalities compared to the younger cohorts?
In 2022, there were 4.7 per 1000 participants screened aged 70–74 with high-grade abnormality detected compared to 14.2 per 1000 participants screened aged 25–74.
Farnsworth et al confirmed previous studies that reported participants with high-risk HPV (HR HPV) and negative LBC, the risk of a biopsy proven high-grade abnormality decreased with increasing age of the participant. However, if the LBC reported a high-grade squamous intraepithelial lesion (HSIL), the risk of a biopsy proven high-grade abnormality was not affected by the age of the participant.
Are there risks in screening the young septuagenarian?
Expect up to 5.3% of this cohort will be HR HPV positive. The challenge for the clinician is knowing how to discuss the significance of an intermediate or higher risk screening result in the young septuagenarian. Important considerations include:
- A discussion on what a positive HR HPV screening test means. There is emerging understanding about immune regulation in the older person and the concept of immune latency. The host immune surveillance following a prior infection may result in the HPV DNA expressed at levels too low to be detected rather than clearance. Over time, as the host immune system becomes less efficient, the HPV DNA levels become detectable again. Currently there are insufficient data in the National Cancer Screening Register (NCSR) or published literature to further risk stratify the aged 70+ with an exit screen reporting a HR HPV, negative cytology and normal colposcopy.
- The relevance of the past screening history to risk stratify. A participant with a known negative screening history is at lower risk of a high-grade abnormality compared to the never-screened, under-screened or participant with a previous high-grade abnormality.
- The importance of the LBC result to risk stratify. When the LBC result is negative, the risk of a high-grade abnormality is low.
- Colposcopy is often challenging as the entire transformation zone (TZ) critical for a comprehensive colposcopic assessment is often not visible (Type 3 TZ). A negative LBC result is associated with a lower risk of a high-grade abnormality and treatment is not recommended on the basis of a persistent HR HPV and negative LBC.
- The purpose of the NCSP is to prevent cervical cancer. A low participation rate results in later stage disease at diagnosis. Later stage disease is more complex to treat and associated with a higher morbidity and mortality rate.
What can you do?
The availability of self-collection has made opportunistic screening more accessible for this cohort. In the first quarter of 2024, 37.7% of all screening tests in participants aged 70–74 was self-collected. This is the highest uptake in any age group.
The young septuagenarian attending the exit screening test who has an HR HPV any type should be referred directly for a colposcopy (Rec 6.23). Early data from the NCSR indicates those with a HPV 16/18 result, 65.6% will attend for a colposcopy within three months and 87.5% within six months of the test result.
It would be beneficial to pretreat this age cohort with vaginal oestrogen (unless otherwise contra-indicated) prior to colposcopic examination.
Conclusions
The young septuagenarian and those aged 70+ constitute approximately 12% of all new cervical cancer cases annually. The benefits of screening this age cohort outweigh the inconvenience of finding a HR HPV with a negative LBC. Data are maturing on how to further risk stratify these participants found to have persistent HR HPV and negative LBC on their exit screening test.
Take the opportunity to offer a clinician or self-collect Cervical Screening Test (CST) to the next never-screened or under-screened young septuagenarian you see.
References available on request
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