Key Results
Incidence of breast cancer
Breast cancer incidence among females is continuing to increase by two per cent per year. At least part of the recent increase in incidence is due to increased screening (Dinh, Khor and Corry, 2005). However, the incidence of breast cancer is expected to increase due to the increased proportion of women ageing into the at risk age group.
Mortality
In Queensland, mortality from breast cancer among females increased slightly by 0.4 per cent per year between 1982 and 1994, but since then it is now the trend in mortality reversed and it is now decreasing by 2.6 per cent per year. This corresponds to an overall decrease in the mortality rate for the nine years from 1994 to 2003 of 20.8 per cent (Queensland Health Information Circular 71, 2005). See Figure 1 below.
This trend is very encouraging and can be attributed to breast cancer screening along with improvements in management and treatment and advances in drug therapy.
Figure 1: Trends in age-standardised mortality for breast cancer among females in Queensland between 1982 and 2003
Annual screening throughput
Figure 2 below illustrates the growth in the number of women screened by the BreastScreen Queensland Program each year between 1991/1992 and 2004/2005. In 1991/1992 just under 25,000 women were screened. With the progressive addition of services to the Program, this figure rose to 201,311 women screened in 2006/2007.
Figure 2: BreastScreen Queensland Program - Annual Screening Throughput
Participation rate
Table 1 shows the participation rates for women screened during the 24-month periods 1996-1997, 1997-1998, 1998-1999, 1999-2000, 2000-2001, and 2001-2002. There has been a significant increase in the participation rate for women aged 50 to 69 years from 42.6 per cent in 1996-1997 to 57.9 per cent in 2005-2006. However, from 1999-2000 to 2005-2006, the participation rate has remained relatively stable, hovering around 57-58%. Although the number of women being screened has increased, the population has increased at a similar rate.
Table 1: BreastScreen Queensland Age-standardised* Participation Rates
|
Age group |
Screening |
No. of |
Estimated |
Participation |
| 40 - 49 yrs | ||||
|
1996-1997 |
58,858 |
240,991 |
24.4% |
|
|
|
1997-1998 |
69,851 |
245,480 |
28.5% |
|
|
1998-1999 |
75,895 |
251,682 |
30.3% |
|
|
1999-2000 |
77,187 |
256,727 |
30.1% |
|
|
2000-2001 |
80,765 |
262,917 |
30.2%* |
|
2001-2002 |
83,389 |
270,480 |
30.8% |
|
|
2002-2003 |
85,285 |
277,394 |
30.7% |
|
|
2003-2004 |
86,766 |
284,558 |
30.5% |
|
|
|
2004-2005 |
92,259 |
290,564 |
31.8% |
| 50 - 69 yrs | ||||
|
1996-1997 |
123,162 |
289,134 |
42.6% |
|
|
|
1997-1998 |
157,798 |
301,490 |
52.3% |
|
|
1998-1999 |
175,595 |
313,365 |
56.1% |
|
|
1999-2000 |
187,759 |
327,725 |
57.4% |
|
|
2000-2001 |
199,837 |
341,474 |
58.7%* |
|
2001-2002 |
208,677 |
355,336 |
58.7% |
|
|
2002-2003 |
277,394 |
374,437 |
58.5% |
|
|
2003-2004 |
226,083 |
390,909 |
57.8% |
|
|
|
2004-2005 |
238,764 |
406,757 |
58.7% |
| 70 - 79 yrs | ||||
|
1996-1997 |
24,196 |
96,174 |
25.2% |
|
|
|
1997-1998 |
29,030 |
98,678 |
29.4% |
|
|
1998-1999 |
33,343 |
100,508 |
32.9% |
|
|
1999-2000 |
37,096 |
104,017 |
35.7% |
|
|
2000-2001 |
39,031 |
105,261 |
37.8%* |
|
2001-2002 |
38,357 |
107,485 |
35.7% |
|
|
2002-2003 |
37,913 |
107,382 |
35.3% |
|
|
2003-2004 |
39,492 |
180,400 |
36.4% |
|
|
|
2004-2005 |
40,166 |
109,361 |
36.7% |
Screening outcomes
During 2005, the overwhelming majority of women (almost 94 per cent) attending for screening were reassured that no sign of breast cancer was found and were recommended for a routine re-screen. Recall to assessment was recommended for approximately six per cent of women screened.
Breast cancer detection
During 2005, 1,162 breast cancers were detected amongst women screened within the BreastScreen Queensland Program. This compares with 1,127 cancers detected for the previous year. Of the 1,162 breast cancers detected in 2005, 81.1 per cent were invasive and 18.9 per cent were ductal carcinoma in situ. The overall cancer detection rate for the BreastScreen Queensland Program in 2005 was 5.8 per 1,000 women screened.
Small cancer detection
A key performance measure for breast cancer screening is the proportion of small cancers detected. Of the 942 invasive cancers detected in the BreastScreen Program in 2005, 62 per cent were less than 15mm in size illustrating that the Program is achieving its aim of early detection.
The small cancer detection rate of cancer <=15mm for BreastScreen Queensland in 2005 was 31 per 10,000 women screened which more than meets the National Standard of >= 25 per 10,000 women screened.
In 2005, approximately 87 per cent of cancers have been detected through the assessment service without the need for diagnostic open biopsy. This allows for one stage surgery and significantly reduces the costs of in-hospital treatment services. This percentage has increased as more BreastScreen Queensland Services have developed an increased technical capacity to undertake more core biopsies.
Treatment
Of all women with breast cancer detected in the BreastScreen Queensland Program during 2003, 70.5 per cent had breast-conserving surgery as their primary treatment and 29.5 per cent of women underwent a mastectomy. However, conserving surgery is differentially distributed, with women in rural and remote areas less likely to have conserving surgery as their primary treatment for breast cancer.
Mastectomy as a percentage of all treatments in Queensland
Figure 3 illustrates the continuing reduction in mastectomy as primary treatment for women screened in the BreastScreen Queensland Program.
In the eight years from 1998 to 2005 there has been a reduction in mastectomies from 38 per cent to 32 per cent.
While this is not the only measure of morbidity clearly there are benefits to women from less invasive surgery and the associated psychosocial impacts of mastectomy.
Figure 3: Mastectomy as a Percentage of Treatment for BreastScreen Queensland Participants (1998-2005)
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