OVERVIEW OF CERVICAL CANCER

Cervical cancer is a major cause of mortality worldwide. The death toll is greatest in populations that lack cervical cancer screening programs.

Cervical cancer is the leading cause of cancer deaths in women in less developed regions. Every year 530,000 women are diagnosed with cervical cancer and more than 270,000 die from this disease.

If early changes in cervical cells are detected through screening programs, cervical cancer is curable. However, if undetected until late in its clinical course, it has a high death rate.

Cervical cancer develops slowly and is linked to HPV infection. Pre-cancerous cervical cells may not cause symptoms and by the time symptoms become apparent, it is often too late for treatment, particularly in resource-poor environments. HPV is found in 99% of the cervical cancer cases.

Progression of HPV infection to cancer is slow, generally taking more than 10 years. Although invasive cancer is most commonly seen in women aged over 45 years, the precursor changes are detectable much earlier.

Variation in incidence
with age

In a study of international incidence rates prior to the introduction of cervical screening, the first onset of cervical cancer occurred at approximately 25 years of age in most populations.

European countries generally showed an earlier peak age (mean peak age, 46 years) and a more rapid decline after the peak than non-European countries (mean peak age, 59 years).

However, the overall shape of the age-specific incidence curve suggests a similar development of invasive cervical cancer within different populations. Because cervical cancer affects relatively young women in their prime of life, it is an important cause of lost life-years in developing countries. Cervical cancer makes the largest contribution to lost life-years from cancer in South-Central Asia.

Mortality rates

Globally, the ratio of mortality rates to incidence rates is 55%. However, mortality rates vary greatly between countries as well as within countries. Incidence and mortality rates also vary with time. For example, a study in China found the mortality rate for cervical cancer to be 10.7/100,000 in the 1970s, but this declined by over 60% to 3.89/100,000 overall in the 1990s.

This decline was not uniform throughout China; in some rural areas in the mid-west (i.e. Wudu in Gansu and Yangcheng in Shanxi), the rate remained high.

Economic costs

The economic costs of cervical cancer consist of both medical costs and costs associated with lost productivity due to premature death. The annual direct medical costs associated with cervical cancer have been estimated at US$300–400 million in the USA. In a recent study designed to determine the costs of lost productivity in the USA due to cervical cancer, it was estimated that 130,377 women would have been alive in 2000 had they not died from cervical cancer. Of these women, 75% died before age 60 and 25% before age 40. With 29% of these women expected to have been working during 2000, the productivity loss due to cervical cancer mortality was estimated at US$1.3 billion in that year.

CURRENT SCREENING METHODS

Pap Tests

The frequently used Pap test has good specificity but relatively poor sensitivity.

The Pap test has been successful in decreasing cervical cancer death rates in industrialized countries. Pap tests, however, are not effective in low resource or developing health economies due to the lack of infrastructure and lack of highly trained personnel to read the smear, and do not detect all pre-cancerous lesions. Pap tests are also labour intensive, complex and tedious.

HPV

The development of cervical cancer is associated with persistent infection with oncogenic types of HPV.

Although HPV DNA testing started to be approved for screening in developed countries, it is a quite expensive process that won’t be affordable for population based screening in developing countries. Furthermore, like Pap tests and Liquid-based cytology, HPV tests need an infrastructure of laboratory facilities which are lacking in developing countries.

Visual Inspection

Visual inspection methods are often used in low-resource settings as they are inexpensive and provide an immediate result.

However, they are relatively non-specific and have low sensitivity.

Liquid-based Cytology

Liquid-based cytology is a variation on the conventional Pap test. Recent research has shown that liquid-based cytology does not show any advantage over conventional Pap tests in terms of sensitivity and specificity.

Vaccine

Although vaccines are effective in prevention of persistent HPV infection, it is essential that women continue to undergo cervical cancer screening because the two HPV vaccines available on the market only cover the types of HPV that cause 70%  of cervical cancer cases, they are only effective for women who have not had sexual contact, and the duration of the effectiveness of vaccines is unknown.

SCREENING STATISTICS

Declines in cervical cancer incidence and mortality following the introduction of universal healthcare in Australia in 1975 probably resulted from greater access to Pap testing, earlier access to diagnosis and treatment services, and improved effectiveness of treatment.

There was a sustained decline in the incidence of cervical cancer in New South Wales (NSW) after the introduction of the NSW Cervical Screening Program in 1992, followed 3 years later by a sustained decrease in mortality from cervical cancer. The substantial reduction is largely the result of the implementation of a population-based organized cervical screening program.

Hong Kong’s cervical cancer rates have declined since cervical screening first became available in the 1960s and routine cytology was systematically introduced as part of antenatal care in the 1980s. The overall age-adjusted incidence of cervical cancer in Hong Kong decreased from 24.9/100,000 in 1972–1974 to 9.5/100,000 in 1999-2001.

In another recent study, cervical cancer incidence and mortality statistics in Hong Kong were examined to estimate the potential number of cancer cases that could be averted and life-years saved after the launch of an organized, population-based cytologic screening recall program in 2004. The estimated numbers of cases projected to be preventable from 2002 to 2016 with organized screening every 1, 3 and 5 years were 4226, 3778 and 2334, respectively.

Although screening has had a major effect on cervical cancer incidence, there is a need for improvement, as there is still a risk of cervical cancer in screened populations. In the UK, the predicted cumulative lifetime incidence of invasive cervical cancer is 1.70% in the absence of screening and 0.77% with pre-2003 screening practice.

A mathematical model of cervical HPV infection, CIN and invasive cervical cancer in the UK predicted a reduction in lifetime incidence to 0.46% if the sensitivity of the screening test regime was increased from its current average of 56% to 90%. This suggests that increasing the sensitivity of screening tests has the potential to further reduce the burden of cervical cancer.

FREQUENTLY ASKED QUESTIONS

How many women die from cervical cancer?
Cervical cancer is the second largest cause of cancer mortality in women. The death toll is greatest in populations that lack screening programs to detect precursor lesions. Every year, 270,000 women died from cervical cancer.

How does cervical cancer develop?
Cervical cancer develops slowly. It is caused by persistent infection of high risk types of HPV and takes more than 10 years to develop to invasive cancer, which gives us good opportunity to detect early abnormalities on the cervix via screening program. Pre-cancerous cervical cells cause no symptoms and by the time symptoms become apparent, it is often too late for treatment particularly in resource-poor environments.

What age group does cervical cancer affect?
Although invasive cancer is most commonly seen in women aged over 45 years, the precursor changes can be detected much earlier. There is a variation in incidence with age. Cervical cancer affects relatively young women, and is an important cause of lost life-years in developing countries.

What is the mortality rate for cervical cancer?
Globally, the ratio of mortality rates to incidence rates is 55%. WHO estimates every year, 270,000 women die from cervical cancer.

What are the risk factors for cervical cancer?
In addition to HPV infection, a young age at first intercourse, a history of more than one sexual partner and high parity are also significant risk factors for cervical cancer. Women who smoke and are infected with HPV 16 are at greater risk for cervical cancer in situ (CIS) than non-smokers.

Is there a relationship between ongoing HPV infection and cervical cancer?
There is a strong association between persistent infection with oncogenic types of HPV and the subsequent development of cervical cancer. Incidence patterns of cervical cancer are linked to HPV infection, however there is large country and regional variation in the distribution of oncogenic HPV types.

Are vaccines against HPV infections effective?
Vaccines against HPV types 16 and 18 could potentially prevent 70% of cervical cancers worldwide. Vaccines against other oncogenic types are not yet available, although the HPV 16/18 vaccines may give some cross-protection against related types. The geographic variation in HPV genotypes is likely to affect the effectiveness of the vaccine.


DISCLOSURE STATEMENT - This device hasn't been approved for Marketing in the US by the FDA. The availability of this and other medical devices in the U.S. require FDA marketing approval. This device counts with CE Mark and is approved for marketing in Europe, Australia and other countries in Asia. Market availability in other countries is dependent on the country's regulatory approval process.


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