Cancer of the uterine cervix is the second most common cancer in women world wide, with 493,000 women newly diagnosed each year, and nearly 273,000 deaths from this disease alone.
There is epidemiological and biological evidence that the high-risk (oncogenic) Human Papilloma Virus (HPV) is the cause of cervical cancer. HPV infection is very common. It is estimated that nearly 80 per cent of sexually active women will acquire this infection at some time during their lives.
However, 90 per cent of them will clear the infection on their own through their immune responses. The remaining 10 per cent with persistent infection are at risk of developing precancerous lesions and some of them may develop cervical cancer. The tragedy is that cervical cancer is an eminently preventable disease.
Creeping up silently
Some risk factors of cervical cancer have been identified which include early age of the onset of sexual activity, multiple sexual partners, multiple pregnancies, other sexually transmitted infections e.g., herpes simplex, chlamydia, gonorrhoea, poor hygiene, immunosuppressive conditions like HIV infection, immunosuppressive therapy, etc.
HPV infection is silent and women may not be aware they have it. More than 100 types of the virus have been identified and about 30 types can infect the genital tract, these are broadly classified as high-risk and low-risk. About 15 HPV types are high risk for cervical cancer. Low-risk types are associated with genital warts. HPV types 16 and 18 are the two most common ones causing cervical cancer globally and in India, while HPV 6 and 11 are associated with 90 per cent of genital warts.
Similarly, precancerous lesions and early stages of the cancer are often asymptomatic. Some women may have symptoms of persistent vaginal discharge, intermenstrual bleeding, postcoital bleeding, postmenopausal bleeding, etc.
Examination by a doctor can raise suspicion if the cervix has an unhealthy appearance. By the time most women with cervical cancer suffer from symptoms and seek medical help it is almost always too late; the disease is already advanced and incurable.
While cervical cancer is the main cancer caused by HPV, other cancers linked with this virus include cancers of the vulva and vagina, oropharynx, anus, penis, etc.
Prevention holds the key
There is no cure for HPV infection. The aim of prevention strategies for cervical cancer is to prevent the HPV infection on the one hand and, to identify women who are at risk of developing cancer (by testing for persistent HPV infection and precancerous changes) on the other.
Secondary prevention includes screening women for precancerous lesions by regular three-yearly Pap smears.
The confirmation of diagnosis requires a small biopsy. Simple outpatient treatments like cryotherapy and LEEP can cure 95 per cent of these precancerous lesions and prevent progression to cancer. Today, an improved method available with a better detection rate is the HPV DNA test. If it is negative, it need not be repeated for 8-10 years. If positive, it is not in itself cause for alarm but requires further monitoring and evaluation.
In primary prevention, prophylactic HPV 16/18 vaccines are available for the two main types which can protect you against nearly 80 per cent of the cases. Two vaccines are presently licensed globally and in India: Quadrivalent (HPV types 16, 18, 6 & 11) and Bivalent (HPV types 16 & 18).
Both vaccines have been shown to be highly safe and effective at preventing infection by the relevant HPV types and also preventing the development of precancerous lesions. Vaccination combined with screening is expected to be an effective, comprehensive strategy for cervical cancer control.
The writer is Additional Professor of Obstetrics & Gynecology at AIIMS, New Delhi and is a leading authority on cervical cancer prevention.