A couple of years ago we wrote a blog piece explaining why in most countries women aged 65 and over do not receive invitations for screening. In this blog, we discuss the risk of cervical cancer in women aged 65 and over, conditional on their screening history between the ages of 50 and 64.
Our recently published study using data from the English cervical screening programme suggests that the decision to offer screening after age 65 should be based on screening history at ages 50 to 64. In fact, results show that the single most impactful policy, in terms of cervical cancer reduction at aged 65-84y, is to screen women who have not attended screening in their 50s once between the ages of 60 and 64y. Such a policy would not lead to any additional screens above what is currently offered and could reduce incidence rates in England by 4.1 per 100,000 women.
What is the risk of cervical cancer in older women?
As discussed previously, women aged 65 who have been screened every five years since age 50 are very unlikely to get cervical cancer in the future. Our study found the cumulative risk to age 84y was 2 per 1,000 women.
About 1 in 200 women who were not screened in their 50s would avoid getting cervical cancer by having a single screen in their early 60s.
In other words, without screening about 8.4 per 1000 women (with a cervix) in England currently aged 60-64y would get cancer by age 84y, but a single test between aged 60-64y would prevent 4.9 of those 8.4 cancers. Five-yearly screening from age 50 to 64y (i.e., three screens) would prevent about 6.8 of those cancers.
Women who have had an abnormal test result between the ages of 50 and 64 had the highest risk of cervical cancer (10 in 1,000).
These results are in line with those reported in a similar Swedish study.
What are the implications of this?
Bottom line – the upper age of screening should be dependent on previous screening participation and results.
Our study reflects the risk of cervical cancer following cytology-based screening. Very few women in our study were screened using HPV as the primary screening test. Some have argued that given the high mortality rates from cervical cancer in women over age 65 and the lower sensitivity of cytology compared to HPV testing women should be offered a ‘catch-up’ HPV test around age 65 before being discharged from the screening programme.
Results from this study suggest that such a ‘catch-up’ screen may be appropriate for women with abnormal screening results prior to age 65. However, given the low lifetime risk, it is safe for women with three negative screens (even if they were cytology-based) after age 50y to exit cervical screening at age 65y.
Cervical cancer rates in older women in England could be reduced by 5.1 per 100,000 (from 14.2 to 9.1 or by 36%) if all those not currently screened aged 60-64y were screened once between the ages of 60-64y. However, more than three quarters (4·1 per 100,000 or 29%) of this added benefit could be achieved by screening the 21% of women in England who have not attended screening since age 50y.
These results suggest that instead of offering a ‘catch-up’ screen, efforts should concentrate on screening previous non-attenders once in their early 60s. We estimate that if one were to screen 80% of these women, over the next 25 years 779 cancers could be prevented in women aged 65 and older. Were this test to be HPV-based the impact will most certainly be even greater.
So what’s the catch?
There is no doubt that trying to engage those who have not participated in screening is challenging, but the benefits it will bring suggest this strategy should be given serious consideration. So far most of the interventions aimed at increasing participation have had at best, moderate impact. Additionally, conventional screening can be uncomfortable or difficult for postmenopausal women and often produces inadequate test results which need to be repeated.
The good news is the development of new screening technologies such as self-sampling (vaginal or urine) and non-speculum clinician taken sampling (a vaginal sample taken without a speculum by a doctor or nurse for HPV testing) may provide the breakthrough needed to encourage higher screening uptake in this population. Research in our group found that offering lapsed attender women aged 50-64 the choice of ordering a self-sampling kit or having a non-speculum clinician sample substantially increased uptake (results not yet published).
It looks increasingly likely that having a choice of screening test will be key to optimising uptake particularly in hard to reach populations such as non-attenders to screening.
The views expressed are those of the author. Posting of the blog does not signify that the Cancer Prevention Group endorse those views or opinions.
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