1301.0 - Year Book Australia, 2005  
ARCHIVED ISSUE Released at 11:30 AM (CANBERRA TIME) 21/01/2005   
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Cancer trends

Cancer is a major cause of death and disability in Australia. It affects both the physical and emotional wellbeing of individuals and their families, and represents costs to the community in terms of health care infrastructure, absence from work, and premature mortality. However, over recent decades developments in the detection and treatment of cancer have improved the chances of survival for people with cancer. Cancer (malignant neoplasm) refers to several diseases which result when the process of cell division, by which tissues normally grow and renew themselves, becomes uncontrolled and leads to the development of malignant cells. These cancer cells multiply in an uncoordinated way to form a tumour. If left untreated, most malignant tumours will eventually result in death. Cancers are classified according to where they initially develop in the body.

The government designated cancer as a National Health Priority Area (NHPA) in 1996, identifying lung, melanoma skin, non-melanocytic skin, cervical, breast, colorectal and prostate cancers, and non-Hodgkin's lymphoma as priority cancers to be targeted (DoHAa). The NHPA initiative focuses public attention and policy on health areas known to contribute most to the burden of disease in Australia, and which have potential for significant health gains (AIHW 2002a).

Early in the 20th century, cancer accounted for a relatively small proportion of deaths (7% of all male deaths and 8% of all female deaths in 1909). The death rate from cancer peaked in the 1980s, then declined slightly from 215 deaths per 100,000 people in 1985 to 188 per 100,000 in 2002, when cancer accounted for 31% of all male deaths and 26% of all female deaths.

Paradoxically, the increased proportion of cancer deaths partly reflects longer life expectancy in the population. That is, cancer is predominantly a disease of the elderly, and the longer people live, the more likely they are to die from cancer than from other conditions.

Cancer incidence

While there has been a decrease in cancer deaths since 1985, the cancer incidence rate increased between 1985 and 2000. In 1985, there were 392 new cases of cancer diagnosed per 100,000 population. A high incidence of prostate cancer, combined with slightly higher rates for breast and ovarian cancer, contributed to an overall peak in cancer incidence in 1994, when 478 new cases per 100,000 population were diagnosed. Cancer incidence then fell to a rate of 451 in 2000.

Cancer incidence among men increased from 481 new cases per 100,000 men in 1985, to a peak of 608 in 1994, declining to 536 per 100,000 in 2000 (graph 9.18). The peak in 1994 occurred around the time when there was a peak in the number of men tested using the prostate specific antigen (PSA) test (Smith & Armstrong 1998). This test identified prostate cancers that previously may not have been diagnosed through other tests or the presence of symptoms (DoHAb).

Women consistently had lower cancer incidence rates than men. In 2000 the cancer incidence rate for women was around 70% of the rate for men. Although the relative growth in cancer incidence was higher among women than men between 1985 and 2000, the increase was more steady over the period.

Cancer incidence is lowest in late childhood and increases with age (AIHW 2002a). The most common forms of cancer among children aged 0-14 years are lymphatic leukaemia, and brain and central nervous system cancers, which together accounted for 51% of cancer incidence in this age group in 2000. For almost all cancers, incidence is higher among boys than among girls (AIHW 2002b).

Graph 9.18: CANCER INCIDENCE(a)



Of the seven priority cancers for which data are routinely collected, the incidence of lung cancer among men, and cervical cancer among women, decreased between 1985 and 2000. There was an increase in the incidence of prostate and colorectal cancer among men; lung and breast cancer among women; and melanoma skin cancer and non-Hodgkin's lymphoma for both men and women (table 9.19).

While changes in the incidence rates for specific cancers may reflect more, or fewer, people developing a type of cancer, they may also relate to medical advances that improve detection and identification of the site of origin of cancer in the body. For example, the increased incidence of prostate cancer has been largely attributed to the PSA test, which increased detection and reporting of latent prostate cancers (Smith & Armstrong 1998). Conversely, the halving of the incidence rate for cervical cancer between 1985 and 2000 (from 15 new cases per 100,000 women to 8) may be partly due to a national cervical screening program introduced in the early-1990s (AIHW 2002a). Cervical cancer is one of the most preventable and curable of all cancers - up to 90% of cases of the most common type of cervical cancer can be prevented if cell changes are detected and treated early (DoHAc). Thus screening, which encouraged women to have regular Pap smear tests, supported more effective control of this cancer.

Smoking is associated with an increased risk of developing many diseases including lung cancer. In 2001, 24% of the adult population were current smokers, a decrease since 1989-90 when 28% smoked. Smoking rates were consistently higher among men. In keeping with this, the rate of incidence of lung cancer was also higher among men. However, the gap between men and women is closing, with the incidence of lung cancer declining among men (from 81 new cases per 100,000 men in 1985, to 62 in 2000) but increasing among women (from 19 to 27). As there is a time lag between exposure to the carcinogenic agents of tobacco and the onset of cancer, this increase reflects smoking patterns of around 20 years ago, when the proportion of female smokers increased relative to male smokers.

Data on non-melanocytic skin cancers are not routinely collected by state and territory cancer registries, and instead, estimates are provided by periodic national surveys. It is estimated there were 374,000 new cases of non-melanocytic skin cancer diagnosed in 2002 (NCCI).


9.19 INCIDENCE RATES(a) OF SELECTED CANCERS

Males
Females


Selected cancers
1985
1990
1995
2000
1985
1990
1995
2000

Prostate
82.8
102.4
167.8
124.9
. .
. .
. .
. .
Breast
1.0
1.1
0.8
1.0
84.2
94.6
115.7
115.4
Colorectal
72.4
74.3
78.2
80.2
54.3
51.4
53.6
53.8
Lung
80.6
78.1
69.8
62.1
19.2
23.7
25.9
27.4
Melanoma skin
33.6
43.1
51.2
53.7
31.3
32.8
36.7
38.0
Non-Hodgkin's lymphoma
16.0
19.5
19.4
21.5
11.4
12.6
15.1
15.6
Cervical
. .
. .
. .
. .
14.5
13.3
10.7
7.6
All registrable cancers(b)
481.2
517.3
587.3
535.7
336.9
355.7
393.3
390.4

(a) Rate per 100,000 population and age standardised to the 2001 population (persons).
(b) Excludes non-melanocytic skin cancers.

Source: AIHW, Interactive cancer data.


Surviving cancer

Measuring the chance of survival for people diagnosed with cancer, relative to people without cancer, assists in assessing the broad impacts of early detection methods such as screening, and the efficacy of treatment. The chances of surviving at least five years after diagnosis with any type of registrable cancer improved considerably between 1982-1986 and 1992-1997 (table 9.20).


9.20 FIVE-YEAR RELATIVE SURVIVAL RATIO FOR SELECTED CANCERS

1982-1986
1987-1991
1992-1997
Selected cancers
%
%
%

Prostate(a)
59.3
64.3
82.7
Lung
9.9
11.0
12.0
Breast(b)
72.3
77.8
84.0
Colorectal
50.6
54.2
58.4
Non-Hodgkin's lymphoma
49.8
52.6
55.1
Cervical(b)
69.6
72.0
74.6
Melanoma skin
87.1
90.2
92.1
All registrable cancers(c)
49.4
53.4
59.9

(a) Ratio refers to males only.
(b) Ratio refers to females only.
(c) Excludes non-melanocytic skin cancers.

Source: AIHW 2001; unpublished data from AIHW for colorectal cancer.


There were improvements in survival ratios for the priority cancers, with prostate cancer showing the greatest relative improvement (about 40%). That is, while there was an increase in the incidence of prostate cancer, there was not an equal increase in mortality. The introduction of PSA testing, combined with the tendency for prostate cancer to have slow, non-life threatening growth, and affect mainly older men, could partly explain the increase in survival ratio between 1987-1991 and 1992-1997 (Stricker & Eisinger 1997; Smith & Armstrong 1998; AIHW & AACR 2003). However, factors other than PSA testing may be involved (Smith & Armstrong 1998, AIHW 2001).

Relative improvement in the survival ratio for breast cancer was similar to that for colorectal cancer (about 15%), although the survival ratio for colorectal cancer was lower. Earlier detection and diagnosis, and improved treatments are likely to have increased the chances of surviving such cancers.

The likelihood of surviving for five or more years after being diagnosed with lung cancer also improved between the 1980s and the 1990s (from 10% to 12%). That said, lung cancer remained the cancer with by far the lowest likelihood of survival of all of the selected priority cancers.

Cancer deaths

The death rate for a specific cancer is influenced both by how commonly it occurs, and by how likely people are to survive it. For example, although non-melanocytic skin cancers are the most commonly diagnosed cancer in Australia, relatively few people die of this cancer if treated early. Death rates from cancer declined for both men and women between 1985 and 2002, although men continued to experience a higher rate of death from cancer than women (table 9.21).

Childhood cancer is relatively uncommon (children aged 0-14 years made up less than 1% of all cancer patients in each year from 1983 to 2000) (AIHW 2002b). However, cancer is a leading cause of death among children aged 1-14 years (118 children in this age group died from cancer in 2002). Death rates for children improved from four deaths per 100,000 children aged 0-14 years in 1993, to three per 100,000 in 2000, reflecting advances in various cancer treatments (AIHW & AACR 2002).

Graph 9.21: CANCER MORTALITY



Of all the priority cancers, lung cancer has consistently been the leading cause of death for men since the early-1950s (AIHW). However, as with incidence rates for lung cancer, the difference between men and women is reducing slightly. Female death rates for lung cancer increased between 1985 and 2002, from 17 deaths per 100,000 women to 24, while the male death rate decreased from 77 deaths per 100,000 men to 53 (table 9.22).

In 1985 there were 36 deaths per 100,000 men as a result of prostate cancer. While there were substantial improvements in the likelihood of surviving prostate cancer between 1985 and 2002, the death rate for this condition stayed much the same over this period (36 deaths per 100,000 men in 2002).

For women there was a decrease in deaths due to colorectal cancer between 1985 and 2002 (from 28 to 20 deaths per 100,000 women). The incidence rate for colorectal cancer remained relatively steady over the period (around 53 new cases per 100,000 women each year), so the reduction in deaths may be due to increased chance of survival. The slight improvement in the survival ratio for cervical cancer combined with the improved ability to prevent cervical cancer through effective screening, resulted in mortality decreasing by more than half.

While the incidence of breast cancer in females increased between 1985 and 2000, the death rates decreased (from 31 to 25 deaths per 100,000 women). This may be attributed to earlier detection and/or improvements in treatment leading to a better chance of surviving the disease for longer.


9.22 DEATH RATES(a) FROM SELECTED CANCERS

Males
Females


Selected cancers
1985
1990
1995
2000
2002
1985
1990
1995
2000
2002

Breast
0.2
0.3
0.4
0.2
0.2
31.3
31.0
29.5
24.7
25.1
Cervical
. .
. .
. .
. .
. .
5.1
4.3
3.8
2.6
2.1
Colorectal
37.9
35.2
33.9
30.5
27.7
28.0
24.3
22.6
20.5
19.6
Lung
77.2
68.5
63.9
54.7
53.3
17.1
19.3
21.9
22.2
23.5
Melanoma skin
6.8
7.6
8.1
7.4
8.0
3.8
3.8
3.6
3.5
3.1
Non-Hodgkin's lymphoma
8.0
10.0
9.9
10.4
9.5
6.2
6.5
7.4
7.0
6.3
Non-melanocytic skin
3.1
3.6
3.8
3.2
3.2
0.7
0.7
1.2
1.0
1.1
Prostate
35.7
39.9
41.4
35.9
35.5
. .
. .
. .
. .
. .
All cancers
287.3
277.7
270.6
246.6
241.3
167.2
162.6
160.3
147.9
150.3

(a) Rate per 100,000 population, age standardised to the 2001 population (persons).

Source: AIHW 2003.


Years of life lost through cancer

Years of potential life lost measures the extent of premature mortality, which is assumed to be any death before the age of 79 years. In 2002 the years of potential life lost through cancer deaths amounted to 189,562 for men and 156,522 for women (table 9.23). For a specific cancer, the number of years of potential life lost reflects not only the incidence and survival rates for that cancer, but the age at which deaths from that cancer commonly occur. For example, although the death rate for non-Hodgkin's lymphoma was higher than for melanoma skin cancer, slightly more years of potential life were lost due to the latter. This indicates that melanoma skin cancer affects people earlier in life, resulting in more premature deaths.

Although death rates due to prostate cancer were the second highest of all the priority cancers in men, this type of cancer resulted in a comparatively low number of years of potential life lost, as it mainly afflicts older men. While a similar number of women died from breast cancer as died from lung cancer in 2002, there were more years of potential life lost through breast cancer (36,684 years) than through lung cancer (22,909), as women with breast cancer are more likely to die at a younger age than women with lung cancer.


9.23 YEARS OF POTENTIAL LIFE LOST(a) FROM SELECTED CANCERS - 2002(b)

Males
Females
Selected cancers
years
years

Breast
221
36,684
Cervical
. .
3,592
Colorectal
22,146
16,299
Lung
40,988
22,909
Melanoma skin
9,178
4,183
Non-Hodgkin's lymphoma
7,730
5,598
Prostate
10,850
. .
All cancers
189,562
156,522

(a) Measures the extent of premature mortality which is assumed to be any death at ages 1-78 years inclusive.
(b) Data are age standardised to the 2001 population (persons).

Source: ABS, Causes of Death Collection.


References

AIHW (Australian Institute of Health and Welfare):
  • 2001, Cancer Survival in Australia, 2001 Part 1: National Summary Statistics, Cancer Series No. 18, 2001, AIHW Cat. No. CAN-13.
  • 2002a, Australia’s Health 2002, AIHW Cat. No. AUS 25, Canberra.
  • 2002b, Australia's Children: Their Health and Wellbeing 2002, AIHW Cat. No. PHE 36, Canberra.
  • 2003, Australian Longterm trends in mortality workbooks, AIHW, Canberra
  • AIHW and ACCR (Australian Institute of Health and Welfare and Australasian Association of Cancer Registries)
  • 2002, Cancer in Australia 1999, AIHW Cat. No. CAN 15, Canberra.
  • 2003, Cancer in Australia 2000, AIHW Cat. No. CAN 18, Canberra.

AIHW, <http://www.aihw.gov.au/cancer/index.cfm>, last viewed October 2004.
Department of Health and Ageing

NCCI, <http://www.health.gov.au/internet/wcms/publishing.nsf/content/cancer-australia-lp1>, last viewed 5 April 2004.

Smith, DP & Armstrong, BK, ‘Prostate-specific antigen testing in Australia and association with prostate cancer incidence in New South Wales’, The Medical Journal of Australia, 1998, vol. 169, pp. 17-20, <http://www.mja.com.au>, last viewed 3 March 2004.

Stricker, PD & Eisinger, DR, ‘Patient preference and prostate cancer screening’, The Medical Journal of Australia 1997, vol. 167, pp. 240-241 <http://www.mja.com.au/>, last viewed 3 March 2004.