Regular Smear Tests Raises Chances of Cervical Cancer Cure

The detection of cervical cancer by screening can considerably increase a women's chance of surviving this malignant neoplasm, which in the early stages may be completely asymptomatic.

The rationale of cervical screening by the Papanicolaou test (Pap smear) is to reduce the incidence of cancer by the detection and treatment of precursors and a secondary aim is the early detection of invasive disease, which might improve the prognosis thereby also reducing mortality from the disease.

Scientists at the Uppsala University (Gävle, Sweden) and the Karolinska Institutet, (Stockholm, Sweden) examined all 1,230 women diagnosed with cervical cancer in Sweden between 1999 and 2001 in a prospective cohort study. The team examined screen-detected cancers, those with an abnormal smear result one to six months prior to cancer diagnosis, as well as symptomatic cancers, which were all the remaining cases.

At least seven years of potential follow-up were available from diagnosis of cervical cancer for all the women. Five years after diagnosis, 440 out of the 1,230 women had died. Among them, 373 had a recorded death due to cervical cancer. Thirty-one women died from other cancers, and 36 died of diagnoses not related to cancer. Results from the study revealed that there was a 92% cure rate for women who attended cervical screening, compared to 66% of women who were diagnosed by symptoms. This finding demonstrates a considerable increase in survival chances for those who attended cervical screening than women who did not. Furthermore, the researchers found that women who were overdue for an examination had lower chances of survival than women who attended screening following an invitation.

In addition, the team found that 75% of the 373 women who died from the disease did not undergo a cervical smear in the advised time frame. Half of the women who died from cervical cancer within five years of diagnosis were over the recommended age for screening. Women with interval cancers and an abnormal smear test result during the past six years had a nonsignificantly higher cure proportion than women with only a normal smear test result. If this difference is real, the reason might be that women with abnormal smear test results are followed up to a greater extent than women with normal smear test results.

The authors concluded that detection of invasive cancer by cervical screening implies a favorable prognosis compared with cancer being detected based on symptoms. The effect was stronger than what is reflected in downstaging and was not attributable to lead time bias. In addition, women with symptomatic interval cancers had a better prognosis than women with symptomatic cancers who did not have a smear test within the recommended screening interval. The effect on cervical cancer cure should be included when evaluating cervical screening programs. The study was published on March 1, 2012, in the British Medical Journal (BMJ).

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Uppsala University
Karolinska Institutet