I am 57 years old. My doctor said that I don’t need a Pap smear every year, and, after I am 65 years old, I may not need one ever again. Is this a recent change?
Your Menopause Question: I am 57 years old. My doctor said that I don’t need a Pap smear every year, and, after I am 65 years old, I may not need one ever again. Is this a recent change?
Our Response: It has been nearly 100 years since Nicholas Papanicolaou and Aurel Babes, following centuries of prior investigators, independently reported that cervical cancer could be identified by sampling the cells on the surface of the cervix. For most of those years, the etiology of cervical cancer remained unknown.
Meanwhile, other investigators were analyzing the role of human papillomavirus (HPV) for venereal warts. These two investigation pathways merged in 1928 with the detection of HPV strain 16 in cervical cancer, leading to the statement, “cervical cancer may be the first human cancer with a single necessary cause.” Rapid progress led to the identity of 12 high-risk strains, with 16 and 18 being the most dominant.
But why HPV? A brief history of the cervix will explain. The critical junction for Pap smear analysis, called the squamocolumnar junction, occurs at the cervical os where the endometrial cells lining the uterus meet the squamous cells lining the outside of the cervix. Seldom does the PAP smear identify abnormal cells higher up in the uterus, and it rarely provides information on other components of the genital tract.
The cells at the squamocolumnar junction originate as stem cells deeper in the tissues. These “baby cells” undergo repeated cell cycling as they mature, ultimately appearing at the surface as adult (and often dead) cells. Critical to this process, this cell cycling is controlled by the P53 gene, a tumor suppressor gene often called the “guardian of the genome.”
Human papilloma virus interference occurs when certain HPV strains produce E6 and E7 proteins. If these HPV strains pass through the tissues to reach the “baby cells,” they can insert those proteins into the DNA of these premature cells during cell cycling, leading to the risk of mutations and, ultimately, cervical cancer. This process, however, is very slow, estimated to require ten to 20 years to develop.
The American Society of Colposcopy and Cervical Pathology recommends no screening for women less than 21 years of age. If testing is negative, cytology testing is recommended every three years for those 21 to 29 years of age; women 30 to 65 years should have HPV and cytology (co-testing) every five years; and no more screening is recommended for women after age 65 or for women who have had a hysterectomy.
It is clear that with the link of HPV to cervical cell changes, significant progress in testing methods and protocols has led to reduced cervical cancer risk, which now accounts for less than 2% of all malignancies in American women.
James Woods |
7/23/2020
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