The National Cervical Screening Program commenced in 1991. The major goals of the Program in Australia are to reduce the incidence and mortality of cervical cancer in women. Cervical screening through Pap smears detects abnormalities of the cervix at an early stage and medical intervention can avert the possible progression to cervical cancer.
This is the ninth annual report on the performance of the Program. Data were provided by state and territory cervical cytology registries and are presented on six indicators which measure program activity, performance and outcome. The key outcome data indicate that the Program has been very successful in meeting the goals of reducing incidence and mortality through early detection and treatment. In the period from 1982–1991 prior to commencement of the National Program, age-standardised incidence of cervical cancer was declining at an average of 0.7% per annum, and mortality was declining at 2.7% per annum. From 1991 to 2003 the average decline in incidence was 5.2% per annum and for mortality was 5.0% per annum (AIHW National Cancer Statistics Clearing House). Furthermore the incidence of cervical cancer among women in the target age range of 20–69 years declined from 17.2 per 100,000 women in 1991 to 9.1 in 2003, and mortality fell from 4.0 per 100,000 women in 1991 to 1.8 per 100,000 in 2004.
The main features in this report are as follows.
- In the two-year period 2004–2005 there were 3,462,907 women who participated in the National Cervical Screening Program. Women aged 20–69 years accounted for 98.4% of the women screened.
- Between the periods 2002–2003 and 2004–2005 the proportion of women aged 20–69 years participating in cervical screening increased from 60.7% to 61.0%.
- There was a steady decline in participation among women aged less than 40 years from 1998–1999 to 2004–2005 but continued improvement in participation for older women in the 55–69 year age group. For example, participation fell from 68.7% in 1998–1999 to 62.9% in 2004–2005 for women aged 30–34 years but increased from 46.5% to 49.7% during the same period for women aged 65–69 years.
The recommended screening interval is two years following a normal (negative) smear.
- Of a cohort of women screened in February and March 2004 who had a normal Pap smear result, 25.3% had a repeat Pap smear within 21 months. It is not known what proportion of this early re-screening was justified on clinical grounds.
- There was a decline in the proportion of women being re-screened early from 32.0% in 1999 to 25.3% in 2004.
Detection of abnormalities
A low-grade abnormality includes atypia, warty atypia, possible cervical intraepithelial neoplasia (CIN), equivocal CIN, and CIN 1. A high-grade abnormality is defined to include CIN 1/2, CIN 2 and CIN 3 and adenocarcinoma in situ.
- In 2005 the screening program detected 31,111 histologically verified abnormalities of which 16,274 were low-grade and 14,837 were high-grade.
- The number of high-grade abnormalities detected per 1,000 women screened aged 20–69 years increased significantly between 1997 and 2005, from 6.4 to 7.5.
- With the exception of a rise in 2000, there has been a decline in the ratio of low-grade to high-grade abnormalities in women aged 20–69 years from 1.35 in 1999 to 1.10 in 2005.
- The number of high-grade abnormalities detected per 1,000 women screened was highest in the younger age groups. For women aged 20–24, the rate of high-grade abnormalities was 19.2 per 1,000 women screened; in contrast the rate was 1.0 per 1,000 women screened aged 65–69 years.
Incidence and mortality
- The number of new cases of cervical cancer has continued to decline. There were 725 new cases in Australia in 2003 compared with 1,091 in 1991 before the start of the organised screening program. The number of new cases of micro-invasive cervical cancers also fell from 166 to 85 over the same period.
- All histological types of cervical cancer have shown a statistically significant decrease in the age-standardised rates per 100,000 women aged 20–69 years with the exception of adenocarcinoma. The incidence of adenocarcinoma declined from 2.7 per 100,000 women in 1992 to 2.2 in 2003. It is possible that this is because these cells may be too deep in the endocervical canal to be easily detected with a Pap smear (Heley 2007).
- Cervical cancer was the 18th most common cause of cancer mortality in Australian women in 2004, accounting for 212 deaths in 2004 compared with 329 in 1991. Although there was some fluctuation from year to year, the age-standardised mortality rate from cervical cancer declined between 1991 and 2004. For all women there was a decline from 4.0 deaths per 100,000 women in 1991 to 1.9 in 2004; this represents a decline of almost 55%. During the same period, for women aged 20–69 years the rate fell from 4.0 to 1.9 per 100,000 women, a decline of 52.5%.
- Women aged 20–69 years from regional and remote locations experienced higher incidence and mortality rates for cervical cancer compared with women in major cities. In 2000–2003, age-standardised incidence was 8.9 per 100,000 females in major cities, 9.8 per 100,000 in regional areas and 12.3 per 100,000 in remote areas. Only the higher rate in remote areas was statistically significant. However, the age-standardised death rate in regional areas of 2.5 deaths per 100,000 females in 2001–2004 was significantly higher than the rate of 1.9 deaths per 100,000 in major cities. Because of small numbers, the death rate of 2.4 per 100,000 in remote areas was not significantly higher than the major cities rate.
Indigenous incidence and mortality
Data on Indigenous incidence rates are not available and only Queensland, Western Australia, South Australia and the Northern Territory have Indigenous mortality registration data of sufficient quality to be published.
- For these jurisdictions in the period 2001–2004, the age-standardised mortality rate for Indigenous women was 9.9 per 100,000 women, more than four times higher than the rate of 2.1 per 100,000 for non-Indigenous women in these states and the Northern Territory.