Current guidelines in the United States recommend cervical screening until 65 years. Researchers investigate the effectiveness of screening in older women.
The high rate of cervical cancer in older women continues to be a concern for countries that have long-established cervical screening practices. By these measures, countries have seen a significant reduction in cervical cancer in women between the ages of 30 to 60 years old. However, the same decline has not been seen in older women. In fact, when comparing women older than 60 years old to younger women, cervical cancer is diagnosed more frequently and at more advanced stages. Determining whether or not to screen older women, and if so, when to stop screening has been a topic of great discussion and the jury is still out on the decision.
In a study recently published in PLOS Medicine, researchers set out to determine when to discontinue screening for cervical cancer and whether continued screening was at all effective in women over 60 years old.
Using data from a national registry on cervical screening, Wang and colleagues identified half a million Swedish women as the study population. They used the Papanicolaou (Pap) test as the screening tool and included data from women born between January 1, 1919, and December 31, 1945. Using these dates as the reference would ensure that the subjects included would be 51 years of age or younger in 1970 and 66 years of age or older by the end of 2011.
The researchers categorized the screening histories of women aged 51-60 years according to five possible results:
1) Adequately screened with normal results
2) Inadequately screened with normal results
4) Low-grade abnormality
5) High-grade abnormality
The main variable of interest was each woman’s first Pap record at age 61-65years and the primary outcome was the development of cervical cancer.
Of the study group, 63% of women aged 61-65 years were not screened. Those who were screened had a higher level of education overall and 60% of women in the study population were screened adequately and had normal results between age 51-60 years. A total of 868 cases of cervical cancer were identified in women aged 61-80 years and the majority of these cases were identified in women who were not screened between ages 61-65 years.
The findings suggest that women who were screened at age 61-65 years had fewer new cases of cervical cancer between age 61-80 years than those who were not screened, however, the extent of the benefit varied depending on their screening history in their 50s. Cervical cancer in older age is less likely to develop if women are screened with normal results in their 50s based on the premise that there is generally less exposure to HPV after reproductive age, and cervical screening after 60 years is less likely to be effective due to the lower factors leading to cervical cancer.
The research results suggest that women who are unscreened or who are screened with abnormalities are at a higher risk of developing cervical cancer, and any screening to follow may reduce any subsequent risk. The researchers conclude that these women should continue to be screened after 60 years old. Women who were screened in their 50s and had a normal result did not appear to have a significant risk of developing cervical cancer. The researchers of this study suggest that the choice of cervical screening be based on the availability of resources, and believe their results can be used as a framework for future studies and cervical screening programs.
Written By Kimberly Spencer B.Sc. (Hons)
References: Wang J, Andrae B, Sundström K, Ploner A, Ström P, Elfström KM, et al. (2017) Effectiveness of cervical screening after age 60 years according to screening history: Nationwide cohort study in Sweden. PLoS Med 14(10): e1002414. https://doi.org/10.1371/journal. pmed.1002414