Early Detection: Screening for Cervical Cancer

Implementation for cytology screening for cervical cancer requires several steps:

A program of health education is needed to raise awareness of the disease and the importance of early diagnosis by screening for curability.
A policy is needed to restrict examination to women over 35 years of age (see below). This may have to be modified if significant numbers of cases of cervical cancer are seen in a country in younger women. Then a practical and effective mechanism to identify women in the target age group of 35 to 59 years of age must be devised.
Female primary health workers are then trained to examine the cervix and take PAP smears, and instructed on proper case finding and referral procedures.
Cytotechnicians and cytopathologists also need to be trained.
Proper cytology laboratories must be established, strategically located geographically, and of such a size that they will handle sufficient smears annually to maintain competence. Quality control is needed.
A link is needed between identification of an abnormality and referral to be sure that all suspected lesions are properly diagnosed and treated, and that women receive proper follow-up.
An information system will also be needed to allow for monitoring and evaluation of the program, including measurement of the downstaging phenomenon.

The natural history of cervical cancer is long and the same considerations apply with cytology as with downstaging. With the onset of sexual activity at about age 13, cervical dysplasia appears about age 18 through 35 years. Only about 8% of cervical cancers are seen during this period, so that examinations here are unlikely to find many cancers. Carcinoma in situ begins about age 35 years through to about age 50 when invasive cancers begin to appear as a prelude to death at about age 55. Since about 92% of cervical cancers appear between ages 35 and 50, this is the age range to target where examinations will be most cost-effective. In some countries a virulent form of cervical cancer is appearing in young women, sometimes in their early 20’s. In this kind of situation the age recommendations have to be modified appropriately.

Process, impact and outcome measures are used to monitor and evaluate secondary prevention programs. For cervical cancer screening by cytology, examples might include (WHO,1995):

Process Measures
More than 80% of women in the 35-59 year target group are educated about screening for cervical cancer.
More than 80% of primary health workers are trained to take PAP smears.

Impact Measures:
Over 80% of women in the target 35-59 year group are screened at least once.Outcome Measures

Short Term: There is more than a third reduction in cases presenting with advanced disease (stage II and beyond).
Medium Term: There is more than a third reduction in the incidence of invasive cervical cancer.
Long Term: There is more than a third reduction in the mortality of cervical cancer.

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