Cervical Cancer: Can it be prevented?
By Dr. Pakhee Aggarwal;
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.
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. HPV vaccines currently available are the prophylactic vaccines, which are most effective in HPV naïve population (before the onset of sexual debut). These have been around for more than a decade, and in countries like Australia, where a nationwide vaccination campaign was followed, resulted in the reduction of pre-invasive cervical disease within just three years of vaccination. The vaccines are administered in 2 or 3 doses (depending on age at vaccination) and provide cross protection from HPV types other than those covered by the vaccine.
HPV infection, though a necessary causal agent for cervical cancer, is not the only one. Other factors like cigarette smoking, early age at first intercourse, multiple sexual partners, multiple pregnancies, low socio-economic status, diet poor in folates and anti-oxidants are modifiable risk factors. These can be impacted on by public education and awareness. Some other factors like older age, immunosuppression, genetic and racial predisposition are non-modifiable risk factors and in such patients, early diagnosis by screening has a more important role to play.
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. Several methods are available for screening, ranging from simplistic and inexpensive to complex and costly. They also vary in their sensitivity and pick-up rates, some can be carried out by trained providers (including non-clinicians), while others require a full setup of laboratory and equipment. The oldest and most well known is the Pap test, which was developed over 60 years ago. Countries who have implemented this test in mass screening, an example being the Nordic countries, have been successful in reducing the deaths from cervical cancer by about half. However, this method is resource and time intensive and therefore has not taken off as the primary method for screening in resource poor nations. Here, another simple technique, using dilute vinegar has shown equal promise at a fraction of the costs. The advantages and disadvantages of each method are explained in detail in the referenced article. HPV DNA testing also forms part of secondary prevention in detecting women who have persistent HPV infection due to its direct correlation with cervical cancer. Its role is dual, both as the sole method of screening, as well as for triaging screen positive women into treatment or observation arms. Its universal use is limited by the cost of the test, although a low cost alternative may soon be available. Molecular biology techniques detecting HPV related proteins are potential biomarkers for cervical cancer prevention as they indicate progressing or aggressive lesions.
The cycle of testing (using a sensitive test at regular intervals), diagnosis (using a highly specific test), treatment (with effective methods and by trained staff) and follow-up (as a part of an organized program with high population coverage) should be completed to ensure the success of screening.
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. In the case of cervical cancer, this phase of precancerous disease may last several years and is hence amenable to treatment. There are two ways to deal with the pre-cancer that is detected. The first is destroying the pre-cancerous tissue using extreme heat or extreme cold and preserving the rest of the cervix. The other method is excising a part of the cervix containing the pre-cancerous zone. The method chosen depends on the type and extent of the precancerous lesion. Screen-and-treat approaches are useful in resource-limited settings, where a suspected precancerous lesion is treated at the same time it is detected (single visit). A trained provider is a must for this. Guidelines for management are available from many international bodies.
Only in pregnancy, the situation is different and a precancerous lesion is kept under follow up until after delivery and then treated.
Thus, prevention of cervical cancer involves a multi-pronged approach of education, creating awareness, advocacy, public-private partnerships for HPV vaccination, screening and early treatment of precancerous lesions before they develop into cancer. The extent of focus on each of these measures may vary between communities and countries based on the availability of resources and healthcare commitments. A holistic approach to prevention, involving locally effective measures and treatment protocols and evaluating their adherence and success over time can help tailor programs and policies to maximize the benefits of cervical cancer prevention programs. Cervical cancer is completely preventable. Cervical cancer can be prevented. However the extent to which we achieve this goal depends on us.
Dr. Pakhee Aggarwal
MS, MRCOG (UK), MIPHA, Fellow Gynae-Oncology – Oxford, Consultant – Obstetrics & Gynaecology.
September 24, 2017
World J Clin Oncol. 2014 Oct 10;5(4):775-80. doi: 10.5306/wjco.v5.i4.775.
Cervical cancer: Can it be prevented? https://www.ncbi.nlm.nih.gov/pubmed/25302177