Last week was Cervical Screening Awareness Week in the United Kingdom; so, in an effort to promote greater awareness of the preventability of cervical cancer development, I will be exploring the importance of screening and the current recommendations and options for doing so.
Globally, cervical cancer was the fourth most frequently diagnosed cancer among women in 2012, with estimates of over 525,000 cases and 265,000 deaths, making it the fourth-leading cause of cancer death. In developing countries, it is the most commonly diagnosed cancer after breast cancer.
Human papillomavirus (HPV) has now been established as the main cause of cervical cancer. Young and sexually active women are more prone to being infected by HPV; though, in most, many of these infections are cleared by the body within 2 to 3 years. Cervical HPV infections are acquired mostly through unsafe sex, but some other factors, such as smoking, oral contraceptives, and HIV infections, also increase the risk of developing cervical cancer even in the absence of an HPV infection.
Cervical cancer can be prevented either by HPV vaccinations or by implementing screening programs for the detection and immediate treatment of lesions that develop due to HPV. According to recommendations made by the World Health Organization (WHO), girls between 9 and 13 years of age are a top priority for HPV vaccination; the secondary target populations for HPV vaccination are adolescent girls and young women. Though the first HPV vaccine was licensed almost a decade ago, only around 75 countries have introduced HPV vaccination as part of their healthcare policies to protect women against cervical cancer, demonstrating a huge gap between the availability and actual usage of HPV vaccination.
The most popular test available for detecting cervical cancer is the Papanicolaou test, which is commonly known as the Pap smear; HPV DNA tests and visual inspection with acetic acid (VIA) are other common methods currently being used. The Pap smear is used to detect lesions in which cervical intraepithelial neoplasia (CIN) can be detected—while CIN is not cancer per se, it can develop into cancer that affects nearby tissues if left untreated. HPV DNA tests also detect the virus when it causes changes in cells of the cervical region; these tests can be used in combination with a Pap smear. However, HPV DNA tests are not recommended for women under the age of 30 because this age group is considered to be sexually active and is more likely to acquire an HPV infection that usually disappears on its own. VIA used in vaginal examinations involves the application of dilute acetic acid (vinegar) to the cervix. Upon the application of dilute acetic acid, the tissue appears visibly white in cases of an abnormality. This test can be performed by trained mid-level healthcare providers and is recommended by the WHO in countries with limited resources for Pap smears and HPV DNA tests.
The national variations in cervical cancer rates are due primarily to the levels of public awareness about cervical cancer and differences in screening test availability, as well as the guidelines promoted across individual countries. For example, cervical cancer screening starts at the age of 21 in the US and at 25 in the UK. Meanwhile, in Australia, current guidelines recommend screening to begin at the age of 18, but newer guidelines—which will be implemented on December 1, 2017—will soon advise starting at 25. This change in Australian guidelines is a result of evidence showing cervical cancer to be quite rare in both HPV vaccinated and unvaccinated young women, and despite screening women below 25 years of age for more than two decades, there has been no change in detection rates and deaths from cervical cancer in this age group. In addition, young women who are investigated and treated for cervical abnormalities have a heightened risk for pregnancy complications.
In the UK, there are efforts to designate the HPV DNA test as the primary means of detecting cervical cancer. In line with the UK National Screening Committee (NSC) recommendations, cytology was replaced by the HPV test as the first stage in cervical cancer screening. The reasons for this decision include:
- The effectiveness of the HPV vaccine to lower the rates of acquiring HPV makes it easier for physicians to recognize those who are at risk, and also makes the pathway for cervical cancer screening more straightforward.
- Earlier screening for cervical cancer allows more women to get screened and increases the chance of survival from cervical cancer.
- If women who are at low risk for HPV undergo testing, their potential for developing cancer in the five years following screening becomes very slim.
- Cytology-based screening requires the collection and skilled interpretation of good samples. The possibility for an incorrect interpretation can lead to flawed results, whereas HPV testing does not depend on skilled interpretation and therefore its results are less prone to an erroneous diagnosis.
- Furthermore, there is a larger variation in the sensitivity of cytology-based testing, ranging from 40% to 80%, whereas the sensitivity of HPV testing is above 85%, making it more capable of detecting true cervical cancer.
The UK has an invitation-based cervical cancer screening program, but certain demographic groups, such as young women, women above 50 years of age, ethnic minority women, and women in low-income groups, have not been taking advantage of this program as evidenced by low participation rates. This is an unfortunate situation because some of the reasons for low participation include fear of being diagnosed with cancer, inconvenience, apathy, and concern about the actual procedure. Women frequently delay their initial screening invitations; therefore, timed appointments and sending vaginal self-sampling kits to those not willing to go to a physician’s office for screening would be a cost-effective means to improve the uptake of cervical cancer screening.
While cervical cancer is deemed to be almost entirely preventable with HPV vaccination and the use of various screening methods, encouraging women to get screened and participating in screening programs remains a challenge that needs to be addressed. Campaigns and initiatives such as the UK’s Cervical Screening Awareness Week are a good start.
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