Abstract

INTRODUCTION

Cancer is one of the leading causes of adult deaths worldwide. Every year about 14 million new cancer cases are detected and 8 million people die of cancer.[1] However, there is a marked difference in the distribution of cancer sites across different regions of the world. In contrast to developed countries, cervical cancer is a public health problem in developing countries like India, so much so that India alone accounts for one-quarter of the worldwide burden of cervical cancers.[1,2] It is the one of the leading cause of cancer mortality, accounting for 17% of all cancer deaths among women aged between 30 and 69 years. It is estimated that cervical cancer will occur in approximately 1 in 53 Indian women during their lifetime compared with 1 in 100 women in more developed regions of the world.[2]

Screening for cancer is known to reduce mortality by early detection and treatment. However, there are two prerequisites for screening to reduce the rate of death from cancer. First, screening must advance the time of diagnosis of cancers that are destined to cause death. Second, early treatment of these cancers must confer some advantage over treatment at clinical presentation.[3,4] Unlike other cancer sites, cervix can be subjected to screening for early diagnosis and treatment. However, despite availability of various cervical cancer screening methods, as well as large burden of disease in India, there is no countrywide government-sponsored public health policy on prevention of cervical cancer by either screening or vaccination or both. Therefore, this study was carried out to understand and present burden of cervical cancer in India, as well as to appraise the various cervical cancer screening methods and studies conducted for evaluating screening test for the detection of cervical carcinoma. However, since India is culturally, economically, and sociodemographically dissimilar from other Western countries, we limited the scope of our study to screening trials conducted in Indian population, so as to provide locally relevant evidence-based recommendations for cervical cancer screening in Indian population.

MATERIALS AND METHODS

RESULTS

DISCUSSION

In today's era, in spite of the availability of HPV vaccines and affordable and effective methods for early detection and treatment of cervical cancer precursor lesions, cervical cancer still continues to be a public health problem in India. The age-adjusted incidence rates of cancer cervix reported by majority of Indian cancer registries are much higher than the world age-adjusted incidence rate of 7.9/100,000 population but is lower or similar to cervical cancer incidence rates of 19.2/100,000 population seen in the South-East Asian region.[1] The high burden of cervical cancer in India and Southeast Asian countries is due to poor to moderate living standards, a high prevalence of HPV (more than 10% in women aged more than 30 years) and due to lack of screening.[27] There is a wide variation (range: 4.91–23.07/100,000) in the incidence rates reported by individual PBCRs [Table 1], more so these extreme rates have been reported by newer registries. This is because some PBCRs are reporting the data for the first time and hence, it needs to be viewed with some caution as in the initial years of registry operation there could be some degree of over/under reporting.[5]

Most of the major registries have shown a decreasing trend of cervical cancer, however, the decrease was very small. The mean annual percentage decrease in the average age-adjusted rate ranged from 1.81% to 3.48% among various registries. It should be noted that in India most of the cervical cancer cases are detected with regional spread of the disease, and a very small proportion are diagnosed at a localized stage. In India, an organized mass-screening program for early detection of cervical cancer is not in practice; hence, this decrease cannot be attributed to screening.[28] Moreover, it is also highly probable that cervical cancer incidence rates are an underestimate for India possibly due to underdiagnosis of cervical cancer cases in rural areas and among most impoverished women, as well as due to noninclusion of subclinical cervical cancers in routine hysterectomy specimens not subjected to histopathology, which is a common practice in many regions of India.[29] On the other hand, it has also been suggested that probably an improvement in the living standard of women may have resulted in a reduction in the incidence of cervical cancer, but the same has not been substantiated.[30] The 5-year age-standardized (0–74 years) relative survival for cervical cancer in India is much lower as compared to certain South East Asian countries [Table 4]. This can be attributed to the absence of a nationwide screening program as survival is determined by age and the extent of disease, with younger women having longer survival.[31] A wide variation of survival rates is also observed between rural and urban India. This could be because Indian registries suffer with the problem of under-reporting of death, which is more pronounced in the rural area. In addition, the lack of health infrastructure in rural India results in lower survival rates as compared to urban areas.

In India, despite such alarming statistics there has been no synchronized initiative from public health authorities for prevention and control cervical cancer. In developed countries, conventional cytology screening programs have shown a marked decline in the incidence of cervical cancer.[27,32] However, its successful implementation requires a variety of requirements to be fulfilled, which are not feasible in many low-resource settings where a high risk of cervical cancer is experienced. For instance, cytology screening requires a laboratory infrastructure, microscopes, several resource personnel (smear collectors, cytotechnicians, and pathologists), consumables (slides, fixative, Pap stain containing five dyes, and three solutions), and several steps with inbuilt quality assurance procedures. Moreover, cytology must be repeated at frequent 3–5-year intervals to ensure satisfactory sensitivity and optimum detection of cervical cancer precursor lesions and repeat visits are necessary after a positive cytology for diagnosis and treatment, which may lead to drop outs. Several years of cytology screening in low- and middle-income countries have not led to significant reductions in cervical cancer in these countries, possibly due to the difficulties in offering high-quality cytology, programmatic deficiencies in follow-up and treatment of screen-positive women, and also due to the considerable financial, technical, and logistic inputs necessary for effective cytology programs.[25,33] Hence, these challenges have prompted the search for programs based on alternative cervical screening tests, which are implementable in resource-poor settings. VIA is one of the alternative methods for cervical cancer screening that has been widely investigated. In our review of Indian studies, the sensitivity of VIA has been found to be better than cytology, but its specificity is lower [Table 4].[16,17,18,19,20,21,22,23,24,25,26] However, the biggest advantage of visual tests is that it can be implemented through primary health-care workers, it does not require a laboratory infrastructure, and the results are obtained immediately following testing, allowing diagnosis and treatment to be instituted during the same visit. It has been well established that cervical neoplasia is caused by persistent infection with certain oncogenic types of HPV. Indian studies of testing for HPV DNA indicate higher sensitivity and comparable specificity as compared to visual inspection and cytology. However, the requirement of sophisticated laboratory infrastructure and high cost make it impracticable to be implementable in resource-poor, low-income countries.

The main objective of any screening program is a reduction in mortality. The efficacy of screening by VIA in reducing the incidence of and mortality from cervical cancer has been investigated through cluster randomized controlled trial in Dindigul (India), a single round of VIA-based screening led to a 25% reduction in cervical cancer incidence and a 35% reduction in mortality over 7 years of follow-up.[34] Similarly, a randomized controlled trial carried out in Maharashtra showed a 31% reduction in cervical cancer mortality in the screening group (mortality rate ratio relative risk = 0.69; 95% confidence interval: 0.54-0.88; P = 0.003) as compared to the control group.[35]

CONCLUSION

The studies conducted in India provide sufficient evidence that cervical cancer screening through simple test like VIA/VILI is affordable, feasible, and an accurate tool for implementation in all health-care settings. In addition, VIA/VILI also provides an opportunity to adopt “see and treat” approach, which is very useful in resource-poor countries where follow-up is poor. These tests can also be easily taught to grass root health workers, who can help in conducting the screening program in remote areas. However, for any cervical screening program to be successful in addition to the use of a reliable and accurate screening test, high rates of coverage and the ability to effectively provide treatment to test positive women are very important. Hence, the development of health services and generation of community involvement are keys to the initiative in reducing the burden of cervical cancer. Our study highlights the success of visual screening tool in early detection and mortality reduction of cervical cancer in a resource-poor setting and thus, provides a unique opportunity for developing countries to integrate screening of cervical neoplasia in primary health-care settings.