Cervical cancer is one of the commonest cancers in women & the leading cause of death due to malignancy in developing countries. In India annually 132,000 new cases are diagnosed & 74,000 deaths occur due to cervical cancer. Cummulative life time risk of cervical cancer in Indian women is 2.5% & death risk is 1.4%. Cervical cancer has a long preinvasive stage & if diagnosed at this stage, curability is 100%.
Know about the Human Papilloma Virus (HPV):
Human Papilloma virus (HPV) infection is the most proven causative factor for carcinoma cervix. HPV is a DNA virus & classified according to DNA sequence. Out of 200 HPV viruses, 40 types spread by direct sexual contact & divided into high risk and low risk group.
HPV 16 & 18 are responsible for most of HPV related cancers. 70% of cervical cancer is caused by HPV 16 & 18.
95% of anal cancer, 70% of oropharyngeal cancer, 65%of vaginal cancer, 50% of vulval cancer & 35% of penile cancer are due to HPV 16 infection.
A barrier contraceptive reduces the risk of HPV transmission but not give complete protection because HPV can be transmitted from uncovered area of skin also.
Vaccination against Human Papilloma Virus :
HPV vaccine is serotype specific with limited cross protection efficacy. It is used for primary prevention & reduces the risk of sexually transmitted HPV infection, if given before sexual activity.
FDA has approved three vaccines (Cervarix, Gardasil and Gardasil 9) to prevent HPV infection. These vaccines contain non infectious virus like particles (VLP) formed from HPV surface component & provide strong protection against new HPV infection but not effective against established HPV infection.
Cervarix is bivalent vaccine and give protection against HPV 16, 18.
Gardasil is quadrivalent and give protection from HPV 6, 11, 16, 18.
Gardasil 9 is effective against 6, 11, 16, 18, 31, 33, 45, 52, & 58.
FDA has approved Cervarix, Gardasil & Gardasil 9 in female ages 9 to 26 yrs for prevention of HPV induced cervical, vaginal, vulval, anal cancers, precancerous lesions and genital warts.
Gardasil and Gardasil 9 are approved for male also & used in male for prevention of anal cancer, precancerous anal lesions and genital warts. Gardasil in male is approved for ages 9 to 26 yrs & Gardasil 9 for 9 to 15 yrs.
Gardasil & Cervarix give 100% protection against serotype( 16 ,18) and effective for at least 8 yrs & 9 yrs respectively, whereas Gardasil 9 is equally effective like Gardasil for serotype (6,11,16 , 18) and 97% effective for serotype 31,33,45,52,& 58 Induced cervical & vaginal lesions ,but exact duration of protection is not yet clear.
NCI licensed only two company Merck & GSK to develop HPV vaccine. HPV vaccine should be given in 3 doses schedule over 6 months period. Gardasil schedule is 0, 2 months, 6 months & Cervarix is 0, 1 month & 6 months.
How should HPV Vaccination be given ?
0.5 ml vaccine should be given intramuscularly over deltoid or anterolateral aspect of thigh & available in sterile suspension as a single dose vial or as a prefilled syringe. It can be given with other vaccines like hepatitis B & Tdap, in lactating mother, immunosuppressed women but not recommended in a pregnant woman.
No serious vaccine related side effects have been reported except mild to moderate pain (83%), swelling with erythema (25%) & fever (4%).Vaccine is contraindicated in patients having hypersensitivity to yeast or any vaccine component. Some patients have syncopal attack so patient should be observed for at least 15 min in lying down or sitting position following vaccination.
HPV Vaccine is not effective against all HPV infections causing cancers so regular screening tests are needed in all vaccinated women.
Cost of HPV vaccine in India is Rs 6000 for three doses of Cervarix and Rs 8400 for Gardasil.
More researches are going on for obtaining information regarding long-term safety of vaccine, the extent and duration of protection, number of doses ,need of different screening methods in vaccinated women, the immune mechanisms of protection, and nature of HPV infections other than vaccine included serotypes.
An ideal HPV vaccine is still required which has both preventive and therapeutic effect.