23 Jan Why screening test is recommended even after vaccination? Let’s talk about it.
Cervical cancer is the fourth most common cancer affecting women worldwide [1]. India alone accounts for one-quarter of the worldwide cervical cancer burden [2]. The Human Papillomavirus (HPV) is considered as one of the major etiological factors for cervical cancer along with other factors [3]. According to WHO (World Health Organisation) regular screening as well vaccination is essential in the fight against cervical cancer. People living in developing, low or middle income countries are at the increased risk of cervical cancer because they do not have access to screening and treatment services. Cervical cancer is a preventable disease and it can be prevented by simply regular screening and vaccination.
HPV infection and Cancer: The human Papillomavirus (HPV) represents one of the most common sexually transmitted infections that cause cervical cancer. Presently, more than 120 HPV types have been described, of which at least 40 are associated with anogenital lesions, 15 of these have been classified as high-risk (HR-HPV) (HPV 16,18,31,33,35,39,45,51,52,56,58,59,68,73 and 82), and 12 low risk (LR-HPV) which include (HPV 6,11,40,42,43,44,54,61,70,72,81 and 89). Among these, infection of HPV types 16 and 18 is found to be the most oncogenic that lead to the development of cervical cancer while the infection of low risk HPV types 6 and 11, is mainly associated with the development of benign lesions and genital warts. Persistent HPV infection causes most cervical cancer as well as some other cancer like anus, vulva, vegina, penis and oropharynx.
In last few decades cervical cancer mortality rates have fallen in most of the developed countries due to screening programmes. However mortality rate in most of the developing countries remain unchanged or risen due to either limited access to health services or mainly due to lack health education and awareness. There is an imperative need for educational intervention to raise knowledge and awareness about HPV associated cancers & their prevention through vaccination in the young adolescent population of India [4].
For cervical cancer prevention, two vaccines, Gardasil (quadrivalent) and Cervarix (bivalent) have been introduced in India for vaccinating young adolescent girls between ages 9–13 and or 13–26 years. The HPV vaccines prevent infection with certain species of HPV associated with the development of cervical cancer or genital warts.
The quadrivalent vaccine protecting against human papilloma virus (HPV) types 16,18,6 and 11 was licensed in 2006, and the bivalent vaccine protecting against infection with HPV-16 and 18 was licensed in 2007. Both vaccines protect against the oncogenic varieties of HPV-16 and 18 that cause 70% of all cervical cancers and precancers, as well as many cancers of the vulva, vagina, anus, and throat (Human papillomavirus vaccines: WHO position paper. 2014 Oct;89,43:465–91). The nonavalent vaccine protecting against HPV types 16,18,6,11,31,33,45,52 and 58 was approved by the USA Food and Drug Administration in December 2014 and can provide a protection against almost 90%.
Why Screening test is recommended even after vaccination?
Even after HPV vaccination, screening test is recommended at regular interval, because the available vaccines do not protect against all HPV types that can cause cervical cancer, girls vaccinated against HPV will still require cervical cancer screening later in their lives.
Prevent Cervical Cancer with the Right test at the Right time:
Common cervical cancer symptoms are excessive vaginal discharge, spotting between the periods and pain during sexual intercourse followed by vaginal bleeding and pain in lower abdomen. But one should not wait for the symptoms to emerge to rush to doctor, “cervical cancer can be prevented with the right test at the right time”. According to CDC (Center for Disease Control and Prevention, USA) you should start getting regular Pap tests at age 21. The Pap test, which screens for cervical cancer, is one of the most reliable and effective cancer screening tests available. Two screening tests can help prevent cervical cancer or detect at early stage. (i) The Pap test is recommended for women between ages 21 to 65. (ii) HPV DNA test along with the Pap test is recommended from 30 years till the age of 65.
The only cancer for which the Pap test screens is cervical cancer. It does not screen for ovarian, uterine, vaginal, or vulvar cancers. So even if you have a Pap test regularly, if you notice any signs or symptoms that are unusual for you, see a doctor to find out why you’re having them. If your Pap test results are normal, your doctor may tell you that you can wait three years until your next Pap test.
If you are 30 years old or older, you may choose to have an HPV test along with the Pap test. Both tests can be performed by your doctor at the same time. When both tests are performed together, it is called co-testing. If your test results are normal, your chance of getting cervical cancer in the next few years is very low. Your doctor may then tell you that you can wait as long as five years for your next screening. But you should still go to the doctor regularly for a checkup.
If you are 21 to 65 years old, it is important for you to continue getting a Pap test as directed by your doctor—even if you think you are too old to have a child or are not having sex anymore.
Cervical Cancer treatment to prevention is the need of the hour:
Prevention is better than cure. More so, when the disease in question is prevalent and has a high morbidity and mortality. We are talking about cervical cancer, the most common cause of cancer related death in developing countries. Prevention can be done at several levels and each level is as important as the other. A combination of primary, secondary and tertiary prevention methods is needed to prevent cervical cancer morbidity and mortality [5].
Primary prevention is the modification of risk factors (where possible) for cervical cancer. This includes prevention of HPV infection by vaccination and following safe sexual practices.
Early diagnosis of precancerous lesions in asymptomatic patients by regular screening constitutes secondary prevention. It also includes carrying out confirmatory tests in screen positive or symptomatic women.
Tertiary prevention serves to manage the precancerous lesions at an early phase before they turn into cancer. This involves the use of therapeutic approaches to destroy or remove the precancerous lesions before they have a chance to convert into cancer.
Cervical cancer is completely preventable. Cervical cancer can be prevented. However the extent to which we achieve this goal depends on us.
Know More: Cover Story, Reader’S Digest, January 2019, Page# 69, “WHEN PREVENTION IS THE CURE” Why women die of cervical cancer even though it’s preventable. By BUSHRA AHMED
Md. Kausar Neyaz,
Ph.D Founder – Bio-Services (http://www.bio-services.org/)
January 19, 2019.
Reference:
1. International Agency for Research on Cancer (IARC), World Health Organization (WHO). GLOBOCAN 2012: estimated cancer incidence, mortality and prevalence worldwide in 2012: cancer fact sheets: cervical cancer. Lyon: IARC; 2014.
2. Ferlay J, Soerjomataram I, Ervik M, Forman D, Bray F, Dixit R. GLOBOCAN 2012, Cancer Incidence and Mortality Worldwide in 2012. Lyon, France: International Agency for Research on Cancer; 2012.
3. Neyaz MK, Hussain S, Hassan MI, Das BC, Husain Bharadwaj M. Novel missense mutation in FHIT gene: interpreting the effect in HPV-mediated cervical cancer in Indian women. Mol Cell Biochem. 2010; 335:53–58.
4. Rashid S, Labani S, Das BC., Knowledge, Awareness and Attitude on HPV, HPV Vaccine and Cervical Cancer among the College Students in India.PLoS One. 2016 Nov 18;11(11):e0166713. doi: 10.1371/journal.pone.0166713. eCollection 2016.
5. Aggarwal P., Cervical cancer: Can it be prevented? World J Clin Oncol. 2014 Oct 10;5(4):775-80. doi: 10.5306/wjco.v5.i4.775.