Notes on the data: Screening programs - Cervical screening

Cervical screening outcomes - abnormality, females aged 25 to 70 years, 2018, 2019 and 2020

Policy context: Cervical cancer is a largely preventable disease in Australia, mainly due to primary prevention measures through the National HPV Vaccination Program, which vaccinates women against the oncogenic HPV (human papillomavirus) types that cause the majority of cervical cancer. Secondary prevention of cervical cancer is through the National Cervical Screening Program (NCSP) which aims to detect and treat precancerous abnormalities before any possible progression to cervical cancer [1]. It is estimated that up to 90% of the commonest type of cervical cancer may be prevented, if cell changes are detected and treated early [2].

Cervical cancer is a rare outcome of persistent infection with human papillomavirus (HPV), and infection with a high-risk HPV type is necessary, although not sufficient, for the development of cervical cancer [3]. On screening, high-grade abnormalities can occur after persistent infection with HPV [1]. The probability of a high-grade abnormality (as detected on histology) progressing to cancer increases with age and extent of abnormality [4], but is still a very rare outcome, with regression rates for high-grade abnormalities estimated to be at least 80% [5].

References

Incidence and mortality of cervical cancer in Australia remain low, consistent with the NCSP's aim to reduce incidence and mortality. In 2018, there were 11 new cases of cervical cancer diagnosed, and 2 deaths, per 100,000 women (aged 25-74). These rates have remained steady from previous years, although it must be noted that both incidence and mortality have halved between the introduction of the NCSP in 1991 to 2002 [1,6]. However, incidence for Aboriginal and Torres Strait Islander women has been estimated to be double, and mortality to be nearly four times, that of non-Indigenous Australian women [6].

References

Australian Institute of Health and Welfare (AIHW). Cervical screening in Australia 2018. Cat. no. CAN 111. Canberra: AIHW; 2018. Available from: https://www.aihw.gov.au/getmedia/8a26b34d-a912-4f01-b646-dc5d0ca54f03/aihw-can-111.pdf.aspx?inline=true; last accessed 17 December 2019
Australian Institute of Health and Welfare (AIHW). Cervical screening in Australia 2010-2011. Cat. no. CAN 72. Canberra: AIHW; 2013.
Bosch FX, Lorincz A, Muñoz N, Meijer CJ, Shah KV. The causal relation between human papillomavirus and cervical cancer. J Clin Pathol. 2002;55(4):244-65.
National Health and Medical Research Council (NHMRC). Screening to prevent cervical cancer: guidelines for the management of asymptomatic women with screen detected abnormalities. (Reference no. WH39). Canberra: NHMRC; 2005 [cited 2013 Oct 18]. Available from: http://www.nhmrc.gov.au/guidelines/publications/wh39
Raffle AE, Alden B, Quinn M, Babb PJ, Brett MT. Outcomes of screening to prevent cancer: analysis of cumulative incidence of cervical abnormality and modelling of cases and deaths prevented. BMJ. 2003;326(7395):901.
Australian Institute of Health and Welfare (AIHW). National Cervical Screening Program monitoring report 2022. Cat. no. CAN 149. Canberra: AIHW; 2022. Available from: https://www.aihw.gov.au/reports/cancer-screening/ncsp-monitoring-2022/summary; last accessed 9 December 2022

Notes: Cervical screening outcomes for the 36 month period to the end of each calendar year are based on the number of women with a high-grade abnormality, detected on histology, as an age-standardised rate of the number of women screened in the corresponding calendar years. Where a woman has more than one high-grade abnormality detected, the most serious is counted. Where a woman has more than one high-grade abnormality of equal seriousness, the last is counted. If a woman has attended more than once in the 36 months she is counted once only, and her age is taken from the first visit. High grade abnormalities are cervical intraepithelial neoplasia (CIN) that has been graded as moderate (CIN 2) or severe (CIN 3), or for which the grade has not been specified, as well as endocervical dyspepsia and adenocarcinoma in situ.

Impact on screening during COVID-19 pandemic: The AIHW report that data show a decline in the number of cervical screening tests from the second half of March 2020. The number of tests remained low throughout April, during which there were fewer than 30,000 cervical screening tests carried out. The number of cervical screening tests increased in May and June, with a slight decrease in July and August, before increasing again in September 2020. Even with these differences, the number of cervical screening tests appear to have levelled off in July to September 2020 (see Did fewer people screen for cancer during the COVID-19 pandemic? At https://www.aihw.gov.au/reports/cancer-screening/cancer-screening-and-covid-19-in-australia/contents/did-fewer-people-screen-for-cancer-during-the-covid-19-pandemic). While there were fewer cervical screening tests in 2020 compared with 2019, the impact of COVID-19 cannot be quantified without further years of data (as 2020 is the first year impacted by the transition to 5-yearly screening).

Geography: Data available by Population Health Area, Local Government Area, Primary Health Network, Quintile of socioeconomic disadvantage of area and Quintiles within PHNs, and Remoteness Area

Numerator: Number of individual women aged 25 to 74 years with a high grade abnormality detected by histology over a 36 month period ending 31 December 2020

Denominator: Number of women aged 25 to 74 years screened over a 36 month period ending 31 December 2020

Detail of analysis: Indirectly age-standardised rate per 1,000 women screened; the standard population is the population of each respective jurisdiction

Source: AIHW analysis of the NCSR (NCSR RDE 3.4.1 07/08/2021).