What causes cervical cancer and how to prevent it?

Posted by Dr Yahya MS on December 25, 2019

Cervical cancer is the second most common cancer in low and middle income coutries after breast cancer and the commonest gynaecological cancer in these countries.

What causes cervical cancer?

Cervicalcancer is caused by persistent infection with high risk human papilloma virus (HPV). The infection is the commonest sexually transmitted infection with 8 out of 10 women contracting the infection during their life time. Several types of
HPV exist, but type 16 and 18 causes 70% of cervical cancer.
Most of the patient infected by HPV clear the infection over time, with few progressing to precancerous and stage of cancer.
Persistence of infection and progressing to cancer is commonly seen in smokers, low socio-economic status, and those with low level of immunity such as those with HIV, diabetes mellitus.

Prevention of cervical cancer

The major approaches to prevent cervical cancer are:
o  Prevention of infection by human papilloma virus
o  Screening and detection of changes in the cervix and treating those changes before it becomes cancer

How can human papillomavirus be prevented?

o  Health education about the cause of the cancer and prevention strategies
o  Practice safe sex: use of condom can reduce, but not totally eliminate the risk of transmission of HPV
o  Delay commencement of sexual intercourse
o  Minimize sexual partners
o  Stop smoking
o  Use of human papilloma virus vaccine

What are the different vaccines for HPV infection?

There are 3 type of vaccines available for prevention. These include:
o  Cervarix this protects against HPV type 16 and 18, which are responsible for causing 70% of cervical cancer.
o  Gardasil apart from protecting against type 16 and 18. Also protect against low risk type 6 and 11 which causes genital warts.
o  Novavalent vaccine provide protection against 9 HPV types.

How are the vaccine given?

Recommendation for the vaccine based on the society for obstetric and gynaecology of Nigeria.
o  Girls aged 9-15years of age should be given a two-dose regimen with a 6 months interval between the doses (0, and 6 months)
o  Women aged 16-26 years can be given a 3-dose regime (0, 1, and 6months)
o  Booster dose is not recommended
o  Not given to pregnant women
o  Since the vaccines do not provide protection against all the HPV that causes cervical cancer, screening for early detection of cervical cancer should be continued after vaccination.

Screening of precancerous lesions

There are 3 basic methods of screening
o  Pap smear: cells are taken from the cervix using a small brush and analyse in the laboratory
o  Human papilloma virus testing
o  Visual inspection: A single visit approach for screening with rapid diagnosis and treatment, used in resource limited settings

Recommendation for cervical cancer screening

SOGON recommendation for cervical cancer screening
Screening should start at age of 25 years and stop at age of 60 years for patient on routine screening with no prior abnormal result.

Where available HPV testing-based screening is preferred. If test is negative then patient is seen in 5 years for the repeat of the test
If HPV test is positive, patient is referred for colposcopy and biopsy (the cervix is examined with help of magnifying instrument and tissue is taken for further tests).

Pap smear should be carried out every 3 years if test result is normal.
If abnormal the further test may be carried out depending on the type of abnormality detected

Visual inspection is mainly carried out where pap smear and human papilloma virus testing are not available. Its not as accurate as other test in diagnosing abnormal cervical changes. It has the advantage of see and treat at the same visit.