Every woman should know it is important to have regular Pap smear test. Since World War II, the test has been the most widely used and successful cancer screening technique in history. It is named after the Greek doctor who invented it – Dr. George Nicholas Papanicolaou.
An article in the Canadian Medical Association Journal (CMAJ January 8, 2013) says, “The incidence of and mortality due to cervical cancer in Canada have decreased substantially in the past 50 years, and long-term survival rates after treatment are high. Lifetime incidence was 1.5 per cent in 1972, and is now 0.7 per cent; risk of death from cervical cancer is now 0.2 per cent. Most advanced cervical cancer (and associated mortality) occurs among women who have never undergone screening or who have had a long interval between Papanicolaou (Pap) tests.”
For example, in 2011, an estimated 1300 new cases of cervical cancer were diagnosed in Canada, with about 350 deaths. The risk increases after age 25 years and older, peaking during the fifth decade of life.
Pap smear test helps pick early lesions before they become cancerous. This means less invasive treatment is required and the prognosis is better. In the same issue of the CMAJ, the Canadian Task Force on Preventive Health Care has published new guidelines for Pap smear test. These guidelines, which are based on the current scientific evidence, are as follows:
-For women aged less than 20 years, no routine screening for cervical cancer. (Strong recommendation; high-quality evidence)
-For women aged 20-24 years, no routine screening for cervical cancer. (Weak recommendation; moderate-quality evidence)
-For women aged 25-29 years, routine screening for cervical cancer every three years. (Weak recommendation; moderate-quality evidence)
-For women aged 30-69 years, routine screening for cervical cancer every three years. (Strong recommendation; high-quality evidence)
-For women 70 years of age or older who have undergone adequate screening (i.e., three successive negative Pap test results in the last 10 yr), routine screening may stop. For all other women 70 years of age or older, should continue screening until three negative test results have been obtained. (Weak recommendation; low-quality evidence)
Where the recommendations are weak, the decision to undergo Pap smear test depends if the health care provider and the patient think that there is an indication to do one. If the woman is sexually active, she has multiple partners or she has sexually transmitted infection then there would be an indication to do one. One drawback with these updated recommendations is they do not address screening with tests for human papilloma virus (HPV), because there is not yet sufficient data on its effect on mortality and incidence of invasive cancer, says the article.
In a commentary related to the guidelines, Dr. Janet Dollin says, “When Dr. Georgios Papanicolaou developed his famous test in the 1940s, we did not know that cervical cancer is a preventable sexually transmitted infection.” The role of cancer causing virus like HPV was not known. We now know infection with specific strains of HPV is a necessary precursor to cervical cancer. Some of these viruses cause genital warts – another sexually transmitted infection.
Dr. Dollin says, “Indeed, improving uptake and access to HPV vaccination and cervical screening would do more to lower the rates of cervical cancer than deciding at what age to start Pap testing and how frequently it should be done.” The National Advisory Committee on Immunization (NACI) recommends the vaccination of boys and girls to prevent the burden of HPV disease.
Dr. Dollin says that the US Preventive Services Task Force recommends screening for women aged 21-65 years with a Pap every three years or, for women aged 30-65 years who want to lengthen the screening interval, a combination of Pap and HPV testing every five years.
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