Performance indicator 6b: Program sensitivity
Summary
- For the index years 2018, 2019, and 2020, program sensitivity for participants aged 50–74 differs by screening round, being higher after a participant’s first screen than after subsequent screens.
- Program sensitivity over the same period for both 0–12 months and 0–24 months (for all screening rounds) was lowest for participants aged 40–49.
Definition
Program sensitivity is directly related to interval cancers. It is the proportion of invasive breast cancers detected by BreastScreen Australia (screen-detected cancers) out of all invasive breast cancers (interval cancers plus screen-detected cancers) diagnosed in program-screened participants aged 50–74 in the screening interval (2 years).
Rationale
High program sensitivity indicates that few cancers in screened participants are missed by BreastScreen Australia – that is, most breast cancers are detected by BreastScreen Australia and reported in Performance Indicator 4 (Invasive breast cancer detection) rather than in Performance Indicator 6a (Interval cancers). High program sensitivity is desirable.
Guide to interpretation
Program sensitivity is disaggregated into time since screening (0–12 months and 0–24 months) and screening round (first and subsequent).
To produce comparable rates from the relatively small number of cases, program sensitivity is reported by 10-year age groups and aggregated over 3 years.
Program sensitivity data are reported as a percentage of all cancers.
The latest program sensitivity data are for participants aged 50–74 screened in 2018, 2019, and 2020 (referred to as index years 2018–2020). These are the latest data available because at least 2 years need to have passed since a participant’s last routine screening mammogram in order to know whether they were diagnosed with an interval cancer in that time – though this time period is often longer than 2 years due to time required for cancer registries to be notified of the cancer and for linkage between the BreastScreen registers and cancer registers to occur.
Results
For participants aged 50–74 in the index years 2018–2020, program sensitivity in the first year (0–12 months) was 92.7% after their first screening round and 90.1% after subsequent screening rounds (Table 6.3a and Table 6.3b).
Program sensitivity in the 2 years (0–24 months) was 84.0% for the first screening round and 77.2% for subsequent screening rounds (Table 6.3a and Table 6.3b).
Program sensitivity differs by screening round, being higher after a participant’s first visit compared with their subsequent visits. This may be because participants at their first screening visit are more likely to be recalled to assessment for further investigation, and thus more likely to have a breast cancer detected.
First screening round | 0–12 months | 0–24 months |
|---|---|---|
Crude rate | 92.7 | 84.0 |
AS rate | 93.3 | 85.2 |
Note: Crude rate is the number of screen detected cancers as a percentage of all cancers (screen detected and interval cancers); Age standardised (AS) rate is the number of screen detected cancers as a percentage of all cancers (screen detected and interval cancers), age standardised to the population of participants attending a BreastScreen Australia service in 2008.
Source: AIHW analysis of BreastScreen Australia data.
Subsequent screening rounds | 0–12 months | 0–24 months |
|---|---|---|
Crude rate | 90.1 | 77.2 |
AS rate | 88.7 | 74.9 |
Note: Crude rate is the number of screen detected cancers as a percentage of all cancers (screen detected and interval cancers); Age standardised (AS) rate is the number of screen detected cancers as a percentage of all cancers (screen detected and interval cancers), age standardised to the population of participants attending a BreastScreen Australia service in 2008.
Source: AIHW analysis of BreastScreen Australia data.
Program sensitivity by age
For the index years 2018–2020, program sensitivity (for both 0–12 months and 0–24 months) was lowest for participants aged 40–49, increasing with each 10 year age group to be highest for participants aged 75 and over (Table 6.4).
These results point to lower sensitivity of screening mammography for participants aged 40–49, meaning that BreastScreen Australia is less accurately able to detect invasive breast cancers in participants aged 40–49 who attend for screening. This is likely to be due to features of young breasts, such as high density, which can make breast cancers difficult to visualise with screening mammography (Irwig et al. 1997; Cancer Australia 2015b).
Age group (years) | 0–12 months | 0–24 months |
|---|---|---|
40–49 | 80.4 | 65.4 |
50–59 | 87.7 | 74.0 |
60–69 | 91.2 | 78.9 |
70–74 | 92.9 | 82.7 |
75+ | 93.3 | 85.0 |
Note: Crude rate is the number of screen detected cancers as a percentage of all cancers (screen detected and interval cancers).
Source: AIHW analysis of BreastScreen Australia data.
Program sensitivity by state and territory
For the index years 2018–2020, for participants aged 50–74, program sensitivity rates for the period (0–24 months) varied across states and territories, ranging from 75.2% to 81.9% (all screening rounds).
As noted for the interval cancer data, both interval cancers and program sensitivity in each state and territory are affected by the varying jurisdictional policies for managing symptomatic women. This affects the comparability of this indicator across jurisdictions.
Cancer Australia 2015b. Early detection of breast cancer. Sydney: Cancer Australia. Viewed 11 August 2023.
Irwig L, Glasziou P, Barratt A & Salkeld G 1997. Review of the evidence about the value of mammographic screening in 40–49 year old women. Sydney: NHMRC (National Health and Medical Research Council) and NBCC (National Breast Cancer Centre).