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Screening for cervical cancer in Australia: future changes to the program and the evidence for screening.

The National Cervical Screening Program (NSCP) was introduced in 1991 in an attempt to reduce the incidence of cervical cancer and associated morbidity and mortality. Since its inception, the incidence of cervical cancer diagnoses and deaths have effectively halved. (1) Despite its success, the environment in which the NCSP operates has changed significantly with increasing knowledge of cervical cancer, vaccinations and the availability of new technologies for screening.

The Australian Government recently accepted recommendations of the Medical Services Advisory Committee to make changes to the National Cervical Screening Program. In light of this, this commentary aims to provide an overview of cervical cancer rates in Australia and the current screening program, and discuss the changes that will come into effect in May 2017.

Whilst cervical screening is beyond the scope of practice for complementary and allied health practitioners, a role remains for health promotion and a duty of care to ensure optimal patient care, hence the importance of understanding these changes.

Cervical cancer in Australia

The rates of cervical cancer cases and deaths in Australia are low by international standards, accounting for less than 2% of all female cancers. (1) Worldwide, cervical cancer is the fourth most common cancer affecting women, and is the seventh most common cancer overall. The majority of cervical cancers, however, occur in less developed regions, accounting for a higher burden of incidence. (1)

The most recent Australian data from the Australian Institute of Health and Welfare (AIHW) reported that in 2011, 801 new cases of cervical cancer were diagnosed with 226 associated deaths recorded in 2012. (1) This corresponded to 632 new cases and 143 deaths in women aged 20-69 years, or 9.5 new cases of cervical cancer and 1.8 deaths per 100,000 women aged 20-69 years. The incidence of cervical cancer in Aboriginal and Torres Strait Islander women was found to be more than twice that of non-indigenous women, with 4-times the mortality rate. (1)

Over recent years, the understanding of cervical cancer has increased with the identification of the causal role of some human papillomavirus (HPV) infections in the development of cervical cancer. (2) Infection with HPV can occur from sexual activity and may lead to viral persistence and subsequent progression to precancerous abnormalities, and finally invasive cervical cancer. (1)

Whilst a number of high-risk types of HPV are recognised, types 16, 18 and 45 are most predominantly associated with cervical cancer globally. In Australia, HPV types 16 and 18 are detected in 70-80% of cervical cancer cases. (3) It is important to note that most women with HPV infections will not develop cervical cancer. (3) Over 70% of cervical HPV infections will clear spontaneously within 24 months, without causing lesions, and only a small proportion of infections will persist beyond 2 years. (4)

Cervical cancer is one of the few cancers that has a pre-cancerous stage lasting for a number of years prior to the development of invasive disease, hence an opportunity exists for early detection, prevention and treatment of cervical cancer. (5) With this knowledge, cervical cancer has been described as a largely preventable disease as cervical cancer does not and will not develop in the absence of the persistent presence of HPV DNA. (2)

In Australia, the understanding of cervical cancer and HPV has allowed for the implementation of both primary and secondary strategies for the prevention of cervical cancer. Primary prevention of cervical cancer is undertaken by vaccination against HPV infections through the National HPV Vaccination Program, established in 2007 to prevent women being infected with a number of HPV types including high-risk 16 and 18. Secondary prevention of cervical cancer is undertaken through population-based cervical screening. (5)

Australia's National Cervical Screening Program

The aim of population-based screening programs for a disease is to reduce the burden of the disease in the community, including disease incidence and associated morbidity and mortality. The Australian Government developed a Population Based Screening Framework, adapted from the World Health Organisation (WHO) principles of screening published in 1968, to guide the introduction of organised screening programs based on disease condition, available screening tests, follow up assessments, treatment, economics, benefits versus risks, and ongoing management criteria. (6)

The NSCP was established in 1991 and is the only population-based screening program that exists for a gynaecological cancer in Australia. The aim of the program is to reduce the incidence of cervical cancer in Australia and associated morbidity and mortality through an organised approach to cervical screening, which aims to detect and provide appropriate treatment and management of high-grade abnormalities before progression to cervical cancer. The target population of the current screening program is women aged 20-69 years. (7) This program is government-funded and is based on the conventional Papaniclaou (Pap) smear, during which cells are collected from the transformation zone of the cervix, the site where most cervical abnormalities and cancers are detected, and assessed through conventional cytology. (5,8)

Routine screening is recommended every two years for women with no symptoms or history suggestive of cervical cancer for women aged 18 years, or 2 years after the commencement of sexual activity, whichever is later. If results from the screening are not negative, then follow up management occurs in accordance with the 2005 National Health and Medical Research Council (NHMRC) guidelines for management of screen-detected abnormalities. (9)

Evaluating the current system

Despite the success of the NSCP with significant reductions in both cervical cancer incidence rates and mortality since its inception, continuous review and evaluation of the appropriateness of the program are required to ensure best practice. Recently, methods of screening, frequency of screening period, and cost-effectiveness of screening, have been subjected to further evaluation.

Screening intervals

The 2-yearly screening interval for Australia has been reported to take into account a safety margin, as it differs to the International Agency for Research on Cancer (IARC) working group review on the effect of screening interval, which concluded that 3-yearly screening conferred a substantial level of protection against cervical cancer and that more frequent screening offered little further protection. (10) The IARC conclusions are supported by a recent analysis of cervical cancer incidence and mortality rates, in which the findings did not support the more frequent recommendations of 2-yearly cervical screening in Australia. (11)

Cost effectiveness

Cost effectiveness studies have reported shifting to a 3-yearly screening program would result in predicted savings of $10-18 million (AUD) annually, which is equivalent to 6-11% of the total cost of the current program, by reducing the number of women undergoing diagnostic and treatment procedures, without any significant increase in cervical cancer cases or deaths. (12)

Accuracy of the cytology

Differences about the accuracy of cytology methods have been reported, with the sensitivity of a single conventional Pap smear reported to range from 51% to 64.5%.13 The AIHW reports that squamous cytology is generally a good predictor of the subsequent histology finding, with a positive predictive value of high-grade squamous abnormalities cytology results reported as 68.3%. (1) Endocervical cytology is also suggested to be a reasonable predictor of the true disease state, with a positive predictive value of high-grade endocervical cytology result reported as 73.0%. It is recognised that the abnormalities preceding adenocarcinoma are less well understood than those preceding squamous cell carcinoma and can be more difficult to interpret. (1)

Critics of the cytology method argue that as cytology is based on subjective interpretation of the cells, it is therefore associated with interpretation and screening errors. One author highlights that the repetitive nature of screening smears leads to fatigue and, invariably, errors and missed lesions, adding that the most critical shortcoming of the Pap test is the high false negative rate. (14)

Effectiveness of the screening program

Despite a low sensitivity, conventional cytology for cervical cancer is reported to be one of the most successful cancer screening tests. Conventional cytology has led to a significant reduction in invasive cervical cancer incidence and associated mortality rates observed in countries that have adopted high-quality and broad-coverage screening programs using the Pap test. (15) In support of this, since the introduction of the NSCD in 1991, both cervical cancer incidence rates and mortality in Australian have effectively halved. (1)

Participation in the screening program not only reduces the risk of cervical cancer for individual women, but high participation rates reduce the overall incidence and burden of disease in Australia, and is hence integral to the success of the screening program. In 2012-2013, more than 3.8 million women participated in the NCSP, accounting for 58% of the target population on women aged 20-69. Participation rates differed slightly based on remoteness ranging from 58-60% for all areas except very remote which was 55%. (1) The current cervical screening program, however, has been associated with lower participation rates in areas of increasing disadvantage, including lower socioeconomic status, at both state and national levels. (1,16)

Studies that have reviewed women diagnosed with cervical cancer have produced mixed results regarding diagnosis and screening history. It has been reported that 80% of Australian women with cervical cancer are lapsed or never-screeners. (17) One review, however, reported 47% of women who developed invasive cervical cancer had adequate screening histories within 5 years of detection, and whilst some women had failed to follow up on an abnormal smear, many had a history of negative smear results. (18)

The introduction of HPV vaccination

In addition to the NCSP, a second program aimed at reducing cervical cancer was established by Australian legislation in 2007 and implemented in 2008. The National HPV Vaccination Program targets girls and boys in their first year of high school (aged 12 and 13 years), with catch-up programs previously available for women up to 26 years until 2009. The HPV vaccine program protects against high-risk HPV types 16 and 18, as well as types 6 and 11. (16,19) Of note, it has been reported that women vaccinated against HPV in the community catch up program are being screened for cervical cancer at lower rates than unvaccinated women, with significantly lower cervical screening participation in women aged 20-24, 25-39 and 30-34. (19)

A changing environment: A time for change

The environment in which the current NCSP has provided great benefit has changed significantly since its introduction with greater understanding of the role of HPV in cervical cancer, the introduction of the HPV vaccination program, and new screening technologies to detect HPV infection. (7,20) As the population and number of women vaccinated against HPV increase, it has been suggested that cervical screening will become less cost-effect over because the average risk of cervical cancer will subsequently decline in the Australian context. (12)

Accordingly, a review of the NCSP has recently been undertaken to ensure the program is based on current best practice and evidence. Following from this, a number of recommendations by the Medical Services Advisory Committee (7) have been considered and accepted by the Australian Government for implementation commencing in May 2017.

The changes to the NCSP include:

* Replacing cytological testing with HPV testing using a molecular diagnostic assay

* Increasing the age of commencement to 25 years

* Screening every 5 years until the age of 70-74 years

* Using partial HPV genotyping and reflex liquid-based cytological tests for triaging those who test positive for HPV

* Availability of self-collection in under-screened and never-screened women

The proposed changes in combination with the HPV vaccination have been reported to have to the potential to reduce the incidence of cervical cancer by an additional 15 per cent. (5)

Evidence supporting the changes

HPV screening methods

In support of HPV-screening methods, a follow up investigation of four randomised controlled trials assessed the relative efficacy of HPV-based screening compared to cytology-based screening for the prevention of invasive cancer in women who undergo regular screening. The authors concluded the HPV-based screening provided 60-70% greater protection against invasive cervical carcinomas compared with cytology. (21) This furthers earlier results from research findings that HPV molecular techniques are better than cervical cytology with respect to diagnostic sensitivity and reproducibility, to detect high-grade lesion precursors of invasive cervical cancer. (15)

Some data, however, has reported that HPV tests have reported reduced specificity and increased sensitivity in younger women compared to older women, defined as 30 years or older. (18) Further to this point, whilst a recent meta-analysis concluded screening of cervical cancer by HPV DNA testing in comparison to cytology resulted in a relatively higher detection rate, it was only found in the 30 years and over age groups, with specificity similar between cytology and HPV methods. Across all ages, the specificity actually favoured cytology, with authors ultimately concluding that HPV DNA testing as a screening method is appropriate with maximum detection and adequate specificity for women 30 years and older. (4)

Age of Screening

Increasing the commencement age for screening of women to 25 years is in line with IARC and WHO guidelines for unvaccinated populations. (5) Furthermore, no change in cervical cancer associated mortality has occurred in women under 25 years since the introduction of the NCSP, suggesting that screening in this age group is not effective. (22)

Interval of screening

The previously mentioned follow up investigation of four randomised controlled trials assessing the relative efficacy of HPV to cytology screening for the prevention of cervical cancer found the decrease in invasive cervical cancer incidence was not significant within 2.5 years but became significant over a longer follow-up period. (21) Importantly, the observed incidence of invasive cervical cancer was lower 5.5 years after a negative HPV test than 3.5 years after a negative cytology test. These findings support the view that 5-year intervals for HPV screening are safer than 3-year intervals for cytology, which is in line with the recommended changes to Australia's cervical cancer screening program. (5)

Self-collection

The recommended availability of self-collection for under-screened and never-screened women may improve participation rates of the program providing access to the test regardless of rurality, ethnicity, socio-economic status or disadvantage status. (7)

High-risk HPV testing from self-collected samples have been reported to be as sensitive, but often less specific for CIN2+ as cytology from clinician obtained cervical samples. (23) As these women are at increased risk of cervical cancer (17), the HPV self-testing recommendation could lead to improved screening participation rates and improve the overall success of the NCSP.

Economic considerations

Cost-effectiveness analyses completed by MSAC concluded that the proposed changes to 5-yearly HPV testing as the screening program are more cost effective than the current 2-yearly Pap smear. (7) This is in accordance with other studies that after reviewing cost effectiveness of screening scenarios recommended the effectiveness and cost-effectiveness of HPV testing as primary screening for cervical cancer in European and American populations. (24,25)

Laboratory considerations

From a laboratory and pathology perspective, the move from a predominantly conventional and liquid-based cytology-screening program to an HPV-screening with liquid-based analysis triage, will result in a reduction of cases that need to be assessed in a laboratory. Pathology interpretation of cellular changes remains of significant importance and the impact of screening program changes on the laboratories merits consideration. (8) Rigorous quality processes and parameters also need to be ensured for HPV testing as a screening tool, and also to colposcopy which will have increased importance in the new program. (26)

The role of complementary and allied health practitioners

Whilst the undertaking of cervical cancer screening is beyond the practice of complementary and allied health practitioners, it remains important to be informed of the changes to the updated screening program that will take effect in May 2017 (summarised in Table 1) to ensure patients are receiving the best care possible.

The HPV vaccines do not cover all cancer-associated HPV types and additionally, as a prophylactic vaccination, it will not protect women who had already acquired HPV prior to vaccination. With reported lower rates of cervical cancer screening in younger Australian women following HPV vaccination (19), changes to the screening program and delaying the age to start screening needs to be monitored to ensure optimal participation levels across all age groups, with young women appropriately informed and motivated to participate.

As health practitioners, we are in the privileged position of being a trusted health care provider and advisor. Ensuring all women in the target population are being adequately screened, with particular consideration to younger women who may have been vaccinated and have demonstrated reduced screening behaviours, and referring to other medical professionals as appropriate for those who have lapsed, is within our duty of care.

References

(1.) Australian Institute of Health and Welfare 2015. Cervical screening in Australia 2012-2013. Cancer series no. 93. Cat. no. CAN 91. Canberra: AIHW

(2.) Bosch FX, Lorincz A, Munoz N, Meijer CJ, Shah KV. 2002. The causal relation between human papillomavirus and cervical cancer. J Clin Pathol 55:244-265.

(3.) Brotherton JM. 2008. How much cervical cancer in Australia is vaccine preventable? A meta-analysis. Vaccine [Internet]. 2008 [cited 2015 May 10]; 26:250-256.

(4.) Pileggi C, Flotta D, Bianco A, Nobile CG, Pavia M. 2014. Is HPV DNA testing specificity comparable to that of cytological testing in primary cervical cancer screening? Results of a meta-analysis of randomized controlled trials. Int J Cancer 135:166-177.

(5.) Medical Services Advisory Committee (MSAC) 2013. National Cervical Screening Program Renewal: Evidence Review. Commonwealth of Australia 2013. Available from: http://www. cancerscreening.gov.au/internet/screening/publishing.nsf/Content/ E6A211A6FFC29E2CCA257CED007FB678/$File/Review%20 of%20Evidence%20notated%2013.06.14.pdf (accessed May 2015)

(6.) Australian Health and Medical Advisory Council. 2008. Population based screening framework. Commonwealth of Australia. Available from: http://www.cancerscreening.gov.au/internet/ screening/publishing.nsf/Content/population-based-screeningframework (accessed May 2015)

(7.) Medical Services Advisory Committee 2014, Standing Committee on Screening. Application no. 1276--renewal of the National Cervical Screening Program. Commonwealth of Australia. Available from: http://www.msac.gov.au/internet/msac/publishing. nsf/Content/1276-public (accessed May 2015)

(8.) Cummings MC, Marquart L, Pelecanos AM, Perkins, G, Papadimos D, O'Rourke P, Ross JA. 2015. Which are more correctly diagnosed: Conventional Papanicolaou smears or ThinPrep samples? A comparative study of 9 years of quality-assurance testing. Cancer (Cancer Cytopathol) 123:108-116.

(9.) National Health and Medical Research Council (NHMRC) 2005. Screening to prevent cervical cancer: guidelines for the management of asymptomatic women with screen detected abnormalities. Commonwealth of Australia 2005. Available from: https://www.nhmrc.gov.au/guidelines-publications/wh39

(10.) Canfell K, Sitas F, Beral V. 2006. Cervical cancer in Australia and the United Kingdom: comparison of screening policy and uptake, and cancer incidence and mortality. MJA 185(9):482-86.

(11.) Simonella L, Canfell K. 2013. The impact of a two- versus three-yearly cervical screening interval recommendation on cervical cancer incidence and mortality: an analysis of trends in Australia, New Zealand, and England. Cancer Causes Control 24:1727-1736.

(12.) Creighton P, Lew JB, Smith M, Howard K, Dyer S, Lord S, Canfell K. 2010. Cervical cancer screening in Australia: modeled evaluation of the impact of changing the recommended interval from two to three years. BMC Public Health 10:734.

(13.) Cuschieri KS, Cubie HA. 2005. The role of human papillomavirus testing in cervical screening. Journal of Clinical Virology 32S:S34-S42

(14.) Franco EL, Mahmud SM, Tota J, Ferenczy A, Coutlee F. 2009. The Expected Impact of HPV Vaccination on the Accuracy of Cervical Cancer Screening: The Need for a Paradigm Change. Archives of Medical Research 40:478-485

(15.) Isidean SD, Franco EL. 2014. Embracing a new era in cervical cancer screening. The Lancet 383:493-493.

(16.) Barbero B, Brotherton JM, Gertig DM. 2012. Human papillomavirus vaccination and cervical cancer screening by socioeconomic status, Victoria. MJA 196(7):444-445.

(17.) Bessell T. 2014. Renewal of the National Cervical Screening Program. Available from: http://www.cancerscreening.gov.au/ internet/screening/publishing.nsf/Content/renewal-ncsp-pres

(18.) Kulasingam SL, Hughes JP, Kiviat NB, Mao C, Weiss NS, Kuypers JM, Koutsky LA. 2002. Evaluation of human papillomavirus testing in primary screening for cervical abnormalities: comparion of sensitivity, specificity and frequency of referral. JAMA 288(14):1749-1757.

(19.) Budd AC, Brotherton JM, Gertig DM, Chau T, Drennan KT, Saville M. 2014. Cervical screening rates for women vaccinated against human papillomavirus. MJA 201(5):279-282.

(20.) Scalzo K, Mullins R. 2015. The recommended interval for cervical cancer screening: Victorian women's attitudes to an extended interval. Aust NZ J Public Health 39 (2):153-156.

(21.) Ronco G, Dillner J, Elfstrom KM, Tunesi S, SNijders PJ, Arbyn M et al. 2014. Efficacy of HPV-based screening for prevention of invasive cervical cancer: follow-up of four European randomised controlled trials. Lancet 383:524-532.

(22.) Australian Institute of Health and Welfare. Cervical screening in Australia 2010-11, supplementary tables. 2013. Cancer series no. 76. Cat. no. CAN 72. Canberra: AIHW

(23.) Snijders PJ, Verhoef VM, Arbyn M, Ogilvie G, Minozzi S, Banzi R et al. 2013. High-risk HPV testing on self-sampled versus clinician-collected specimens: a review on the clinical accuracy and impact on population attendance in cervical cancer screening. Int J Cancer 132(10):2223-2236.

(24.) de Kok IM. 2012. Primary screening for human papillomavirus compared with cytology screening for cervical cancer in European settings: cost effectiveness analysis based on a Dutch microsimulation model BMJ 344:e670.

(25.) Goldhaber-Fiebert JD, Stout NK, Salomon JA, Kuntz KM, Goldie SJ. 2008. Cost-Effectiveness of Cervical Cancer Screening With Human Papillomavirus DNA Testing and HPV-16,18 Vaccination. J Natl Cancer Inst 100:308-320.

(26.) Farnsworth A. 2014. Changes to cervical screening in Australia: applying lessons learnt. MJA 201(5):245-246.

Jodie Tester

Private practice Melbourne, Victoria, Australia

Contact: jodie@jodietester.com.au
Table 1: Changes to the National Cervical
Screening Program and considerations
for practice

Key changes:

* Replacing cytological testing with HPV testing
* Increasing the age of commencement to 25 years
* Screening every 5 years until the age of 70-74 years
* Using partial HPV genotyping and reflex liquid-based
  cytological tests for triaging those who test positive for HPV
* Availability of self-collection in under-screened and never-screened
  women

Considerations:

* No changes this year/2016 with women to maintain
  current recommended screening intervals
* Women women who have been vaccinated against HPV
  are still at risk of cervical cancer and need to be vigilant in
  undertaking cervical screening
* CAM practitioners can have a role in health promotion and
a duty of care to ensure adequate screening
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Title Annotation:Commentary
Author:Tester, Jodie
Publication:Australian Journal of Herbal Medicine
Article Type:Report
Geographic Code:8AUST
Date:Dec 1, 2015
Words:3697
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