Previously, women were advised to screen for cervical cancer with an annual Pap smear. This was a precaution based on the high number of cases of cervical cancer affecting women at the time despite the fact that it had been decades since Georgios Papanikolaou had developed the vaginal smear that would become the primary method of screening for cervical cancer.
Detecting cervical cancer in its primary stages enables treatment, and the implementation of screening protocols in the 1950s resulted in an immediate decline in the number of cervical cancer deaths in the country. By 1996, cervical cancer had gone from being ranked as the number one deadliest cancer in women, to number eleven. In 2010, there were 12,200 cases of cervical cancer and 4,210 deaths, most of which occurred in women who had not previously been properly screened for the cancer.
Image by Ed Uthman (Flickr).
The threat of cervical cancer continues to be real, but proper screening is a way to safeguard against the disease. After reviewing the efficacy of pap smears and testing for human papilloma virus (HPV) as ways to detect cervical cancer, the United States Preventive Services Task Force (USPSTF) published their recommendations in the journal Annals of Internal Medicine. This update comes nine years since the last recommendation issued by the USPSTF, and is echoed by The American Cancer Society, the American Society for Colposcopy and Cervical Pathology and the American Society for Clinical Pathology.
These recommendations lengthen the period of time between screenings and specify appropriate age-ranges for screening. Previously, it had been recommended that a woman’s first screening occur within three years of her first sexual activity, but in these new guidelines, the onset of sexual activity no longer has a bearing on when testing should begin. Everyone should begin at age 21, even those who have been vaccinated against HPV.
Women between 21 and 30 are now recommended have a Pap smear every three years, whereas previous recommendations suggested annual screenings. HPV testing should not be a part of screening for women under 30 because the prevalence of this type of infection can lead to false positives that don’t necessarily indicate precancerous cells.
Whereas previous guidelines stated that women between 30 and 65 who had previously had normal Pap smears could lengthen the time between screenings to three years, it is now recommended that they screen both with a Pap smear and an HPV test once every five years.
Women who have a normal Pap smear but a positive HPV test result are no longer recommended to have an immediate colposcopy (the examination of the cervix and vagina). Instead, they are recommended to repeat the tests or have a gene test to determine whether they have HPV 16 or 18 -- the most high-risk types of HPV, which account for 70 percent of all cervical cancer cases. Women whose Pap result is abnormal but who do not test positive for HPV should repeat the tests, or simply have another HPV test in a three-year period as a follow-up.The breakdown
- Women between the ages of 21 and 65 who have a cervix, regardless of sexual history, should screen for cervical cancer with a conventional or liquid-based Pap smear every three years.
- Women 30 to 60 should screen with a Pap smear every five years, provided they also get tested for HPV. Women younger than 30 are not recommended to test for cervical cancer with HPV testing alone or in combination with a Pap smear.
Not recommended to screen due to considerations that the possible harm outweighs the benefits:
- Women younger than 21
- Women over 65 who have received screenings throughout their lives and are not at risk for cervical cancer
- Women who have had a hysterectomy that removed the cervix and do not have a history of precancerous lesions or cervical cancer
The USPSTF makes it clear that these recommendations do not apply if a woman has a history of cervical cancer, has been exposed to the hormone DES in utero, or if her immune system has been compromised as a result of the human immunodeficiency syndrome (HIV) or for some other reason. If you are not sure whether the guidelines apply to you, please discuss your concers with your doctor.The reasons for the changes
According to the USPSTF, the decrease in recommended screenings is based on their conviction that the harms of annual screening outweigh the benefits. Their data strongly suggest that not all precancerous lesions are likely to become problematic: many may actually regress on their own, or develop so slowly that they never reach clinical significance in a woman’s life.
As it is, abnormal test results often lead to invasive procedures such as colposcopy (the examination of the cervix and vagina) and biopsy (the removal of tissue for further analysis) that can result in infection, bleeding, and pain, without the certainty of an adequate diagnosis. Cervical conization and loop excision (techniques used to remove the tissue found to have precancerous cells) -- which are common treatments for screenings that show precancerous cells -- carry the risk of infection, hemorrhage, and pain. Though studies are not conclusive, these treatments have been linked to cervical incompetence (the dilation and thinning of the cervix before a pregnancy has come to term), premature rupture of the membranes (which induces premature labor), premature delivery, low birth weight, and perinatal death (the death of a fetus or infant).
“Cervical treatments may increase the risk for adverse pregnancy outcomes (for example, cervical insufficiency and preterm delivery) in women who have not yet completed childbearing,” the USPSTF clinical guidelines read.
Given that many abnormal cervical cells will resolve on their own or fail to grow to the point they will pose a risk to a woman, these procedures to diagnose and treat all abnormal tissue constitute, according to the USPSTF, overdiagnosis and overtreatment. In their opinion, the new guidelines provide the best balance between benefit and harm.The details of this business
Sex should not determine the onset of testing. Cervical cancer in women younger than 20 is rare, accounting for 0.1 percent of cases. Fewer than 16 deaths from cervical cancer occurred in women under the age of 20 between 1992 and 2008.
Cervical cancer is not more aggressive in older women than in younger women. In all cases, onset can take over a decade. The survey of data reviewed by the USPSTF also found that abnormal growth of cells in the cervix peaks in the mid-reproductive years and begins to decline in a woman’s 40s.
The inclusion of HPV testing as part of the screening protocol is big news, as -- despite the strong evidence linking HPV to cervical cancer -- the USPSTF had been reluctant to include it among their recommendations, noting in October that there wasn’t enough evidence to recommend it. Their opinion changed after a review of more recent scientific literature on the topic. That said, screening with HPV tests lead to a higher number of false positives, which may not necessarily indicate the existence of a precancerous cells. HPV is generally a transient infection that resolves itself in the bodies of people whose immune systems are not compromised (as they are, say, in the case of those who are HIV positive, for instance). If the immune system does not resolve the infection and the HPV is a cancer-causing type, the infection can cause the body to incorporate HPV gene sequences, resulting in precancerous cells.
Of the more than 120 types of HPV that have been identified, 15 are high risk, three constitute a probable high risk, and 12 pose a low risk.
Information in this chart from “Epidemiologic Classification of Human Papillomavirus Types Associated with Cervical Cancer”
The HPV vaccine is highly effective at preventing HPV 16 and 18. However, because 30 percent of cervical cancers are caused by types of HPV other than 16 and 18, it is important to screen as recommended to ensure optimal prevention against other carcinogenic types of HPV. It’s also worth noting that the duration of coverage as a result of receiving the vaccine is not yet known.
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