Wednesday, July 18, 2012
New recommendation about Pap smear screening for cervical cancer--we REALLY don't need this test yearly!
In 1941 Dr. Papanikolaou and his colleague, a gynecologist Dr. Herbert Traut, published a paper in the American Journal of Obstetrics and Gynecology describing how to make the diagnosis, and at some point screening for uterine cancer by sampling cells shed from the lining of the uterine cervix became a common practice. Dr. P. himself appears to have been a major force in the practical aspects of making screening an expected part of being female, at least in the US.
All of this gets just a touch confusing to those not familiar with the layout of the female genital tract and the words used to describe its cancers. Just south of the belly button lies a triumvirate responsible for producing babies. The uterus receives fertilized eggs from either of two ovaries by way of the fallopian tubes and the cervix (latin for neck) of the uterus is a tiny canal which permits passage of sperm for fertilization and eventually passage of a baby in the other direction. The most common kinds of uterine cancer are cancers of the skin type cells lining the cervix and cancers of the glandular cells lining the body of the uterus. We call the first cervical cancer and the second endometrial cancer, but Dr. P. originally called them both "uterine cancer." The Pap smear is only good for detection of cervical cancer.
The technique used in obtaining the Pap smear when I first learned how to do it 25 years ago was to take a small rounded wooden spatula and rotate it in the opening of the cervix, smearing the goop obtained on a slide and then applying a fixative which was sometimes just plain hairspray. Eventually we started using little bitty bottle brush thingies instead of or in addition to the little spatula, which got better samples but caused more bleeding and discomfort, and a few years ago we were told that it was even better if we took the little brush (which had undergone another transformation to something that looked like a tiny broom) and swished it around in a fixative and had the lab apply it to a slide. This sample could also be tested genetically for viruses and sexually transmitted pathogens, which before had required a separate sample. It was also more expensive and we were reimbursed more. Funny thing.
In 1984 when I performed my very first pap smear we knew that cervical cancer was more common in women with multiple sexual partners and almost unheard of in women who had never been sexually active. In the next couple of years the increasing abilities of scientists to manipulate viruses in the lab led to the discovery that human papillomavirus , a sexually transmitted wart virus, could cause cervical cancer, and over the next several years it became widely accepted that this virus was necessary for the development of cervical cancer. There are many different types of human papillomavirus and only some of them can cause cancer. There are other factors that can increase a woman's risk of cervical cancer including smoking, immune suppression such as in HIV and genetic predisposition. A vaccine against human papillomavirus was released in 2009 and a 3 dose course of this significantly reduces a woman's risk of developing invasive cervical cancer.
Recommendations about Pap testing have changed significantly over the years, but it seems to me that doctors are particularly slow to adjust to guidelines. When we found out that human papillomavirus was the culprit agent and that it was sexually transmitted, women were told that they needed to get yearly pap smears starting with or before they became sexually active. Several years ago the recommendations changed to recommend 3 yearly pap smears starting at the first sexual activity and then repeating the test every 2-3 years until age 65 at which time testing could cease. Women who had had hysterectomies with removal of the cervix could forego pap smears entirely. These recommendations were especially unpopular with gynecologists in my community who continued to do yearly Paps and Paps after hysterectomy for many years (I think some of them are still doing this.) In 2009 women were told that they didn't need to start testing until age 21 or until 3 years after "sexual debut" and could go 3 years between testing after age 30 if their results were normal.
Just last month the US Preventive Services Task Force released evidence based guidelines on Pap testing that are even more relaxed that 2009, which makes me, as a doctor and as a woman who gets Pap tests, very happy. Cervical cancer screening should not begin until age 21, even if a woman becomes sexually active significantly before this age. After that, she should be screened only every 3 years. After reaching the age of 30 she can be tested with a standard pap smear and for evidence of HPV and if those are both negative she can have pap smears only every 5 years. She can also choose to have every 3 year testing with just the pap smear. The more expensive pap testing with the cells collected in liquid and sent to the pathologist is not more accurate and so we don't need to be doing that routinely, though it does allow for the DNA testing with only one specimen. Women who have been regularly tested can stop screening at age 65 and women who have had hysterectomies for non-malignant disease don't need paps. All of these recommendations do not apply to women who have had abnormal testing and to women who are infected with HIV. Why no HPV testing before age 30? Because apparently HPV is very common in young sexually active women and comes and goes, not requiring treatment most of the time.
But some people (especially doctors) argue that Pap smears are easy, so why reduce the frequency of testing and risk missing some disease? Pap smears are easy, but not harmless. Women are pretty good sports about Pap testing, but it is actually kind of awful to go into an impersonal doctors office, get naked, put on a skimpy gown, spread your legs (just about as vulnerable a position as I can imagine) and have a near stranger poke something (a speculum, usually made of plastic and prone to producing disconcerting clicks and pinching tender flesh) into one's private parts, followed by scraping the soft distal protrusion of a delicate internal organ, usually resulting in bleeding and cramping. But that's just the beginning. If the test is abnormal, repeat testing often occurs more often than yearly, and may lead to destruction of tissue with risks of infection, significant bleeding, work loss and future difficulty getting or remaining pregnant.
Most cervical cancer deaths occur in women who have never had Pap testing, especially women in developing countries and disadvantaged women in the US. Reduced frequency of testing may make it feasible to offer testing to more women and to have it be more acceptable to them. HPV vaccination certainly has great promise in reducing cervical cancer especially for women who don't have access to regular health care, but at this point does not influence recommendations for frequency of Pap testing. Newer recommendations for less frequent testing do offer those of us who dreaded our regular physicals relief from the burden of excessive testing.
I, for one, am happy to forever retire the expression "annual pap smear."