Recent months have witnessed considerable focus on HPV vaccines through
two channels: (i) academic presentations at national, regional and
local scientific events by eminent experts as well as the recent
President’s Page(1) and (ii) commercial promotion through the mass
media by manufacturers of these vaccines. IAP also has recommended the
vaccine(2) on the grounds that (i) cervical cancer is the most
common cancer, and cancer related cause of death in Indian women, as per
the National Cancer Registry; (ii) cervical cancer is responsible
for 132,000 cases and 74,000 deaths annually; (iii) compliance with
annual Pap smear screening is low; and (iv) the currently available
vaccines are safe and efficacious. Therefore the following issues are
pertinent.
Data from the Indian National Cancer Registry (Table
I) record that (i) total number of cervical cancer is 7012
from the population-based survey(3), and 12595 from the hospital-based
survey(4); (ii) mortality rate is 18%, unlike 56% suggested; (iii)
cervical cancer is the second most frequent malignancy in women after
breast cancer; and (iv) incidence is maximal beyond the fifth
decade and not in younger age-groups. It could be argued that the National
Registry is limited in its reach and extrapolations on limited data could
give the oft-quoted figure of 132,000 cases. However, it appears as if the
National Registry data is being downplayed in favor of sources suggesting
higher burden, a déjà vu of the hepatitis B related hepatocellular
carcinoma scenario some years back(5).
TABLE I
Cervical Cancer in India: National Cancer Registry 2001-2003
Assuming that the data quoted in the presidents
column(1) are correct, it translates to 56.1% mortality in Indian women
compared to 54.6% mortality in the rest of the world; making it difficult
to accept that "mortality among Indian women is almost double compared to
that for the world."(1)
A very recent large-scale population-based screening
study using sophisticated methods to identify HPV in cervical samples of
30-59 year-old ever-married women(6), detected HPV in only 10.3% with
almost similar prevalence across different age strata. Even among the "HPV
positive" women, only 36.7% had lesions of-cervical intra-epithelial
neoplasia (CIN) grade 1 or higher, emphasizing that HPV infection is not
synonymous with (pre)cancerous lesions. In addition, the frequency of
cervical lesions was similar across various age groups (38% in 30-39 yr,
39% in 40-49yr and 29% in 50-59yr), although detection of cervical cancer
was highest in the oldest age bracket.
Based on the above data, if HPV vaccination still
merits consideration in India, the vaccine must guarantee protection
(against cervical cancer, not merely HPV infection) for at least 3-4
decades after primary immunization. Such information is not available at
present from anywhere in the world.
Additional considerations must take into account (i)
the limited practical experience from HPV vaccination programmes
worldwide; (ii) question-able acceptance of a vaccine to prevent a
sexually acquired infection that sometimes (but not always) causes cancer,
and that too only if vaccination is completed before exposure; (iii)
vaccination does not protect against all causes of cervical cancer, hence
HPV vaccine is not synonymous with cervical cancer vaccine; and (iv)
some developed countries have rejected a vaccination program for these
reasons(7).
The question of recommending a vaccine to those who can
afford it as against those who need it(1,2), and that too with the aim of
increasing awareness among physicians and people(1) raises ethical issues
over and above the epidemiological and economic aspects.
Screening programs are designed to identify the cohort
that needs to undergo diagnostic investigations, and not to treat those
who test positive, hence "screening in the absence of a treatment program"
would not be automatically unethical, as suggested(1). HPV vaccination
does not replace annual screening programs for cervical intra-epithelial
neoplasia; hence its low level of coverage(1) argues against a vaccination
program rather than in favor.
Therefore, there are several considerations that need
to be resolved before recommending/prescribing/using HPV vaccines in
India.
References
1. Choudhury P. Preventing cervical cancer:
Pediatrician’s role. Indian Pediatr 2009; 46: 201-203.
2. Indian Academy of Pediatrics Committee on
Immunization (IAPCOI). Consensus recommen-dations on immunization, 2008.
Indian Pediatr 2008; 45: 635-648.
3. Indian Council of Medical Research. National Cancer
Registry Programme. Consolidated Report of Population Based Cancer
Registries 2001- 2004, December 2006. Available from: http://icmr.nic.in/nerp/report_pop_2001-04/cancer_p-based.htm.
Accessed on March 19, 2009.
4. Indian Council of Medical Research. National Cancer
Registry Programme. Consolidated Report of the Hospital Based Cancer
Registries: 2001-2003, December 2006. From: http://icmr.nic.in/ncrp/report_pop–2001-04/cancer-04/cancer_p-based.htm.
Accessed on March 19, 2009.
5. Puliyel J, Rastogi P, Mathew JL. Hepatitis B in
India: Systematic review and report of the ‘IMA sub-committee on
immunization’. Indian J Med Res 2008; 127: 494-497.
6. Sankaranarayanan R, Nene BM, Shastri SS, Jayant K,
Muwonge R, Budukh AM, et al. HPV screening for cervical cancer in
rural India. New Engl J Med 2009; 360: 1385-1394.
7. National Board of Health. Reduction in the risk of
cervical cancer by vaccination against human papillomavirus (HPV) - a
health technology assessment. Copenhagen: National Board of Health, Danish
Centre for Health Technology Assessment, 2007; 9: 1-14. Available from:
www.dacehta.dk. Accessed on March 19, 2009.