Routine Cervical Cancer Screening Warranted Beyond Age 64

April 2014, Vol 5, No 3

Results of a new study investigating the probability of a cervical cancer diagnosis among women aged 65 to 83 years using data from the UK Cervical Screening Call/Recall System indicate that the current practice may need to be changed. The new data show that the odds of such a diagnosis were 25% lower in women who had regular screening between the ages of 50 and 64 years compared with women who did not have regular screening. Although the protective effect diminished gradually, it was still significant up to age 83 years, according to the investigators (Castañón A, et al. PLoS Med. 2014;11:e1001585).

Furthermore, the team calculated that there would be 149 fewer cervical cancers per 100,000 women if women continued to be screened for cervical cancer until age 75 instead of age 65.

“Based on these results, we believe women should be screened beyond age 50, with at least 1 screen after turning 60, and possibly continuing screening until age 75,” said lead investigator Peter Sasieni, PhD, Professor of Bio­statistics and Cancer Epidemiology, Wolfson Institute of Preventive Medicine, Queen Mary University, London.

The methods used by Dr Sasieni and colleagues included matching 1341 cases of invasive cervical cancer of women who were diagnosed at ages 65 to 83 years with 2646 controls matched for age and place of residence. A weighted logistic regression model was used to calculate the absolute risks for being diagnosed with cervical cancer.

The screening model involved the last 3 negative tests and having no high-grade cytology between the ages of 50 and 64 years.

The researchers could not collect data on potential confounding factors, such as sexual behavior and smoking, because this information is not gathered in the database they used. However, they made allowances for these factors by using sensitivity analyses.

Risk for Cervical Cancer
Dr Sasieni and coinvestigators calculated an odds ratio (OR) of 0.25 for the risk for cervical cancer between the ages of 65 and 83 years among women who had been screened at least once every 5.5 years between ages 50 and 64 years compared with those who had not been screened during those ages. Even women who had been screened only once every 9 to 15 years between the ages of 50 and 64 years were at a lower risk for cervical cancer in later years, with an OR of 0.54.

However, the researchers also found that the protective effect of screening before age 64 years is reduced with advancing age. In women aged 50 to 64 years with a screening interval of 5.5 years or less compared with no screening, the OR for a cervical cancer diagnosis between the ages of 65 and 69 years was 0.12, compared with 0.27 for women aged 70 to 74 years, 0.46 for ages 75 to 79 years, and 0.49 for ages 80 to 83 years.

The team also estimated the possible effects of risk factors on which no data had been gathered, including on sexual behavior and smoking. They found that these factors could increase the risk by 18%. That translates into an OR of 0.14 instead of 0.12 of developing cervical cancer in women aged 65 to 69 years, 0.33 instead of 0.27 in women aged 70 to 74 years, and of 0.54 instead of 0.46 for women aged 75 to 79 years.

The team’s modeling of the effect of stopping screening at 75 years versus at 65 years per 100,000 women yielded 149 fewer cancers with the former scenario, based on cumulative incidence data from 1975.

In addition, the model suggests that there would be 182 additional cancers per 100,000 women if screening stopped at age 55 years.

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