Cervical cancer screening

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A prostate cancer cell

Dr Fungisai Hove (MBChB,
MMed Obstetrics and Gynaecology, ITP-SRHR).Dr Fungisai Hove (MBChB, MMed Obstetrics and Gynaecology, ITP-SRHR).Dr Annie Fungai Muyotcha (MBChB, MMed Obstetrics and Gynaecology, ITP-SRHR)Cervical cancer is the 4th most common cancer in women worldwide and the 4th leading cause of cancer related deaths. Worldwide, an estimated 528 000 women are diagnosed with the disease and 266 000 die from it every year. The greatest burden of disease is in developing countries like Zimbabwe that have a burden of 90 percent of the cases and deaths. This is mostly attributable to the lack of population-based cervical cancer screening and preventive programs in these countries.In sub-Saharan Africa, cervical cancer is the most common cause of cancer and cancer related deaths among women. The incidence of this disease is steadily increasing in sub-Saharan Africa, with more than 75 000 new cases and 50 000 deaths yearly, which is further increased by HIV infection.

Cervical cancer is the most common cancer in black women in Zimbabwe.It accounts for 35,5 percent of all cancers and an estimated 2 270 women are diagnosed with the disease annually in Zimbabwe as evidenced by data from Zimbabwe National Cancer Registry (2014). Cervical cancer is caused by Human Papilloma virus (HPV), a virus NOT related to HIV, but is acquired through sexual intercourse, just like HIV virus. Unlike HIV, HPV virus does not enter the blood, it mainly affects the outer surface of female and male genital tracts. The most common types are HPV 16 and 18, which are associated with the development of cancers of the cervix, vagina, vulva, penis, anus and                                                                                                               throat. A total of 15 different strains that cause cancer have been identified. Other strains, most commonly HPV 6 and 11, are associated with development of warts which are not cancerous. The natural history of HPV infection can progress to the infection being cleared by the person’s immune system and the patient may either remain asymptomatic or have transient symptoms, or the infection can persist. Persistent infection by any of the 15 strains leads to the development of cervical cancer. There is high prevalence of HPV infection in the Zimbabwean population, with 24,7 percent of women being HPV positive.Not all women infected by HPV will develop cancer.  Before cervical cancer develops, a woman with HPV strain that causes cancer goes through stages of changes in her cervix called pre-cancer on average for 10-20 years if she is HIV negative. It is this precancerous stage that is detected by cervical cancer  screening.
The good news is that cervical cancer can be prevented. Primary prevention is achieved by administering the HPV vaccine before sexual debut and also by ensuring consistent safe sexual practices. Cervical cancer screening is a form of secondary prevention. It aims to detect and treat precancerous lesions before they progress to invasive cancer.  The mortality due to cervical cancer has been significantly reduced in countries with well implemented cervical cancer screening programs. Cervical cancer screening is sadly underutilised in Zimbabwe. According to the Zimbabwe Demographic Health Survey (ZDHS) 79 percent of women in Zimbabwe are aware of cervical cancer screening but only 13 percent of women surveyed had ever been screened. Community education is required to encourage women to use the facilities available for screening. Public-private partnerships in Zimbabwe have embarked on large scale awareness programs for cervical cancer screening which are ultimately aimed at increasing uptake of screening services.The purpose of screening women for cervical cancer is to accurately identify women with pre-cancer changes, offer them effective treatment that will prevent them from developing cervical cancer. Having said that, it is important to note that although the majority of cases of cervical cancer can be prevented by routine screening and timeous treatment of precancerous lesions, no one screening or treatment modality is 100% effective. The efficiency of such interventions is improved by adhering to evidence based guidelines for screening and treatment strategies. Such guidelines have been drafted by several expert committees across the world after perusing the currently available evidence from published clinical research. Methods of screening for cervical cancer can be classified as:Visual Cytological Genomic (Molecular)Visual Inspection with Acetic Acid plus Cervicography (VIAC) Pap smear High risk HPV DNA testingVisual Inspection with Lugol’s Iodine (VILI) Liquid based cytology

Testing for low-risk (non-oncogenic) HPV types has no role in evaluating women with abnormal cervical cytological results.VIAC is what is widely available in the public health sector in Zimbabwe and the other methods are more available in the private sector.Visual methods of cervical cancer screening involve direct inspection of the cervix with the naked eye or with minimal magnification. Abnormal changes to the cervix are enhanced after application of 3-5 percent dilute acetic acid (VIA) or Lugol’s iodine (VILI), and these can be identified by the naked eye. Cervicography is the use of a camera lens to magnify the cervix and then projecting the image onto a screen to improve the pick-up rate of abnormal lesions of the cervix on visual inspection. Studies done in low resource countries have shown that VIAC is very well accepted, feasible and safe.The overall cost of running a population based visual inspection program is significantly lower than all other methods of cervical cancer screening. It requires much less infrastructure and technical support than cytological and genomic tests.This makes it a very attractive public health intervention for low resource countries.  In Zimbabwe, as in other countries that have embraced visual methods, there is also a drive for a “see and treat” approach. As abnormal results are reported within a few minutes of having the visual inspection, immediate treatment can be offered to patients. This presents another advantage of such programs as fewer patients with abnormal results are lost to follow-up as they wait for results. Screening with VIA should offered to all sexually active women from 25 years of age up to 50 years or before menopause. HIV infected women should be screened for cervical cancer pre-cancer as soon as HIV test is confirmed.Cytology based tests involve microscopic examination of the cells collected from the neck of the womb (cervix). Cells are reported abnormal if they are different from the norm in terms of size, shape, multiplication tendencies and cell nucleus attributes. The Pap smear is one of the cytological based screening tests available. It was invented by Georgios Papanikolaou, in the 1940s. It has been the mainstay of cervical cancer screening. This test involves the collection of cells from the cervix using a brush or spatula.A smear of the cells is then prepared and is sent to the laboratory to be examined under a microscope by a specially trained cytologist. In liquid based cytology, the cells are collected the same way as for Pap smear but are placed into a liquid preparation before examination. Liquid based cytology removes debris such as blood and discharge. Both are equally sensitive and specific in identifying precancerous cells.In Zimbabwe there are no guidelines for screening with Pap smear as we do not have a national cytological based screening program. Cytological tests are generally not as accessible in the public health sector. Comparative studies have shown that VIAC has a higher sensitivity than cytological tests, but it has a lower specificity. This means that VIAC has a greater ability to correctly diagnose women who truly have precancerous lesions (sensitivity), but is not as good as cytological tests at correctly identifying those that truly do not have precancerous lesions (specificity). HIV negative women should be screened once every 3 years by either visual or cytological methods, while HIV positive women should be screened every year.  For women aged 30 years and above they can have cytological screening every 3 years or screening with high risk HPV DNA testing. After the age of 65 a woman can stop screening provided she was having regular screening prior to that and had normal results in the past. When abnormal cells are detected follow up diagnostic testing with a colposcopy is indicated.Genomic tests for high risk HPV (HR-HPV) are the newest modality in the screening protocols for cervical cancer. The test can be run on the same sample collected for liquid based cytology. There are several methods of identifying the presence of HPV DNA and also to specify the strain the HPV in the sample. The identification of HR-HPV DNA is considered a positive result and the patient should have a biopsy taken from the cervix to make a diagnosis of precancerous lesions or cervical cancer. The addition of HR-HPV DNA testing to cytology allows screening to be done once every 5 years if results are negative. International guidelines recommend that this method of screening should start at the age of 30years. HR-HPV DNA tests are currently only available in the private sector. When results of visual inspection are abnormal, the patient can either be treated immediately or referred for further investigation by colposcopy. Methods used for immediate treatment are cryotherapy or loop electrosurgical excision procedure (LEEP), also called the large loop excision of the transformation zone (LLETZ). Cryotherapy involves cold ablation (freezing) of the abnormal cells at the cervix causing them to die. LEEP involves the removal of the transformation zone of the cervix which contains the abnormal cells using an electrified thin wire loop. Both procedures can be done under local anaesthetic without the need for theatre.An abnormal cytological result can be followed up with HR-HPV DNA testing or immediately referred for colposcopy. Colposcopy is a procedure where the cervix is primed with dilute acetic acid and then observed through a magnifying lens. A small amount of tissue is collected by biopsy to be examined under a microscope and confirm either precancerous lesions or early cancer. The treatment of precancerous lesions of the cervix or early cancer is highly successful. However if patients develop advanced cancer, as happens in those women who are not screened routinely, treatment becomes less successful, more expensive and is itself associated with more complications than the treatment modalities aforementioned. Invariably women who have not been routinely screened present with end-stage cervical cancer which can only be managed palliatively without hope for cure.In ConclusionCervical cancer is a significant cause of morbidity and mortality in Zimbabwe. The cost to the individual, family, community and nation, of treating cervical cancer goes beyond just dollars and cents. Different methods of screening are now available at different levels of health care all over the country and we would like to add our voices to the public appeal and encouragement for women of all walks of life to regularly seek out cervical cancer screening services. We believe in empowering communities by providing information and we hope that by discussing the methods of screening we have also dispelled misconceptions. As a parting shot, we would also like to make mention of HPV vaccination. A pilot project has already been successfully conducted in the country and we eagerly await the roll-out of the national program. The vaccine is currently only available in the private sector. The target population for the national program will be adolescent girls. There are vaccines which prevent HPV 16 and 18 infection, while others cover for a combination of high and low risk HPV strains. The vaccine works by averting infection by the specific strains, but it does not treat an active infection. It is therefore most effective if administered before sexual debut.

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