Prevention of cervical cancer: screening through pap smear is
Medicine has widened with valuable discoveries on , treatment and prevention of
diseases. An important discovery was made in 1920 , on prevention of cervical cancers in
‘ Pap smear’ or ‘ cervical cytology’ is a simple screening test. This was introduced by
Dr.George Papanicolaou in 1920 as he found that malignant tumors of the cervix shed
cancerous cells into the vaginal fluid. Then he developed a quick and simple screening
test to detect the presence of abnormal cells in a sample obtained through cervical
scraping. The term pap smear has been derived according to the name of
Dr.Papanicolaou. It is possible to find the evidence for the disease years before any
visible manifestations are present.
The cervical cancer has a wide age incidence , but the commonest age period is that
between 45 and 55. It is uncommon in virgin and more common in females who are
having many sexual partners or first sexual contact at a younger age. Giving birth to
many children, smoking tobacco and acquiring the disease of genital warts due to some
type of human papilloma viruses are among other risk factors. Co infection with
Chlamydia trachomatis and Herpes simplex type 2, immunosuppression and certain
dietary deficiencies are suggested as other probable cofactors.
Cervical cancer bears the second position in the cause of female cancer mortality
worldwide with 288,000 deaths annually. About 510000 cases of cervical cancer are
reported each year with nearly 80% in developing countries.
In Sri Lanka it was estimated that 1544 women are diagnosed with cervical cancers and
840 die from the disease annually. It ranks as the second most frequent cancer among
women in Sri Lanka, with the crude incidence rate of 16.4 and mortality of 8.9 in
Incidence of cervical cancer compared to other cancers in women of all ages in Sri Lanka
in 100,000 population
Breast cancer 23.2
Cervical cancer 16.4
Oesophageal cancer 11.0
Oral cancer 8.7
Thyroid cancer 5.4
Cervical cancer mortality compared to other cancers in women of all ages in Sri Lanka
in 100,000 population
Breast cancer 10.1
Oesophageal cancer 10.0
Cervical cancer 8.9
Ovarian cancer 5.3
Oral cancer 4.7
The two topics of cervical cancer and Human papilloma virus ( HPV ) are closely
associated with the recognition of this virus as a risk factor for the disease. There are
more than hundred related viruses in the group of Human papilloma viruses. Some types
of HPV infection may cause genital warts and are transmitted through sexually. The
high risk HPVs which implicate with cytological changes in causation of cervical cancer
includes, types 16, 18, 31, 33, 35, 39, 45, 51, 52, 56, 58, 59, 66, 68 and 73. It should be
mentioned that the majority of these high risk HPV infections subside on their own
without propagating into the stage of cancer.
Currently a vaccine has been introduced in few countries with the objective of
prevention of infection by some types of HPV. This HPV vaccine is recommended for
teenage girls between 11 and 12 years of age. It is also recommended for girls and
women age 13 through 26 years of age who have not been vaccinated or completed the
three doses of vaccine. If a female is expecting a protection from the relevant type of
viruses, she must get the vaccine before becoming sexually active , when there may be an
exposure to HPV. Females who are sexually active may get less benefit as they may have
already infected with a HPV type, targeted by the vaccine.
The price of the HPV vaccine is very high as in the case of some other vaccines. There
are two HPV vaccines namely, Bivalent vaccine ( Cervarix) and Quadrivalent vaccine
( Gardasil/ Silgard). According to the information given, these vaccines are targeting
two types of HPV among several types of related viruses.
Worldwide , HPV 16 and 18 the two vaccine preventable types , contribute to70% of
cervical cancer cases. The next common HPV types in the most part of the world namely
31, 33, 35, 45, 52 and 58 which account for an additional 20% of cervical cancers are not
covered with the vaccine.
Most countries have estimated the prevalence of the HPV infection among females
through pap smear or cytological screening. According to the data of World health
organization ( WHO: summary report update, February 2010 ) , HPV prevalence in
women with normal cytology was reported as 7.9 % in South East Asia and 11.4 % in
the world. Most frequently occurring ten HPV types among women with and without
cervical lesions in South East Asia and the world are as follows.
South East Asia World
HPV Type % HPV Type %
16 68.2 16 54.4
18 14.1 18 16.5
45 9.0 58 5.1
33 4.7 33 4.7
35 4.4 45 4.4
31 3.2 31 3.6
58 2.8 52 3.4
59 1.9 35 1.9
11 1.8 39 1.3
56 1.7 59 1.3
Surprisingly no data available relevant to the HPV prevalence or ten most frequent HPV
types among women with or without cervical lesions in Sri Lanka. As such the country
represent the empty areas in the relevant graphs or tables , prepared by WHO. In other
words, there are no clues about the common types of HPV infection of women in our
country , at least to justify the introduction of a new vaccine, which is targeting only
minimal types of the relevant virus.
Recently, it was revealed in the media that a Bivalent vaccine of HPV has been
introduced with the approval of Sri Lanka Drug Control Authority but the justification of
the HPV vaccine to our country is questionable at the moment. The cost effectiveness of
this procedure must be measured with the data of current HPV prevalence of the country
and also the available alternative ways in prevention of cervical cancer such as cervical
cytology or pap smear.
The cervical cancer screening coverage in Sri Lanka is very low with the current
estimates of 1.3 % in all women aged 18 to 69 years.
Cervical cancer screening coverage in Sri Lanka
1.3 % All women aged 18-69 years screened every 3 years
1.7 % Urban women aged 18-69 years screened every 3 years
1.2 % Rural women aged 18-69 years screened every 3 years
The best and profitable way in prevention of cervical cancer is increasing the pap smear
coverage instead of promoting an expensive vaccine to add extra burden to the
immunization programme. The public should be aware of the risk factors of cervical
cancer and the importance of regular screening in five year interval. The facilities
available for cervical cytology screening must be developed further to attract them in
using these services. The discovery of early cytological changes will allow necessary
treatment and stop the progression of the disease. Every citizen should be responsible in
finding the best solution in prevention of cervical cancer. Yet this solution should not
have an unnecessary burdens to the country and society .
Dr. SHANTHA HETTIARACHCHI
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