Summary
Incidence and mortality
Australia
Breast cancer was the most common cancer diagnosed in women in Australia in 1990, apart from non-melanocytic skin cancers, and it was the most common cause of cancer death. In1990-1992, an average of 7,516 women were diagnosed annually with breast cancer and, on average, 2,458 women died each year of the disease.
Incidence rates increased between 1982 and 1992 but mortality was stable. In this time period:
- incidence increased by 1.5% annually from 57 per 100,000 woman-years in 1982 to 67 per 100,000 woman-years in 1992
- mortality stayed around 19 to 20 per 100,000 woman-years.
Incidence and mortality increased greatly with age:
- incidence rose steeply to 50 years of age and continued to increase, although more slowly, in women at older ages
- breast cancer was rare in women younger than 40 years of age, 15 per 100,000 woman-years in 1987-1992
- incidence increased nine-fold compared with that in women younger than 40 years of age to 138 per 100,000 in women in their 40s, by another 1.5-fold to 207 per 100,000 at 50-69 years of age and again by 1.3-fold to 267 per 100,000 in women 70 years of age and older
- death from breast cancer was extremely rare in women 40 years of age and younger in 1987-1992 at 3 per 100,000 woman-years
- mortality increased ten-fold compared with that experienced by younger women to 30 per 100,000 in women in their 40s, by another 2-fold to 69 per 100,000 at 50-
- 69 years of age and with close to another doubling to 125 per 100,000 in women 70 years of age and older.
The most substantial increase in age-specific incidence rates between 1982-1986 and
1987-1992 was recorded in women 50 to 69 years of age. The increase in incidence in this age group was:
- from 176 per 100,000 woman-years in 1982-1986 to 207 per 100,000 woman-years in 1987-1982.
Mortality from breast cancer in women in Australia from 1921 to 1994 was consistently higher in older than younger women and relatively stable over time in all age groups.
States and Territories
Age-standardised incidence rates increased in each State and Territory between 1982 and 1992 whereas mortality changed very little. Mortality rates tended to be higher in Victoria than in other States and Territories and lower in Queensland than elsewhere for women 65 years of age and older.
Histopathological types
Most breast cancers (81%) were ductal carcinomas and 8% were lobular carcinomas. The occurrence of these two types differed by age:
- incidence of ductal carcinoma increased steeply with age to an annual rate of 201 per 100,000 women aged 70-74 years, which was seven times the rate in women in their 30s
- incidence of lobular carcinoma was relatively constant at rates between 14 and 20 cases per 100,000 women in all age groups from 45-49 to 80-84 years. ·
Comparisons
Place of birth
Mortality from breast cancer in Australian women differed by country of birth. Compared with Australian-born women:
- mortality was higher in women born in the UK and Ireland
- mortality was lower in women from some countries in eastern and southern Europe and Asia.
A national dataset for breast cancer incidence in overseas-born women was unavailable. In women in NSW, breast cancer incidence was higher in New Zealand born women compared with women born in NSW and lower in women from southern European countries and China.
Regional comparisons
Relatively little information was directly available for estimating variations in breast cancer incidence and mortality by Aboriginality, place of residence or socioeconomic status. Analyses of available data indicated that:
- mortality from breast cancer in rural regions was lower than in urban regions
- the more southerly states had higher mortality rates
- breast cancer incidence increased with increasing socioeconomic status in urban
- NSW and in Melbourne
- mortality from breast cancer showed no relationship to aggregate socioeconomic characteristics of geographical areas
- breast cancer mortality in recent years was as high in Aboriginal and Torres Strait Islander women as in non-Aboriginal women in Western Australia and the Northern Territory
- breast cancer incidence in Aboriginal and Torres Strait Islander women in these areas appeared to be low, although under ascertainment was a likely contributor.
International incidence and mortality
Incidence and mortality varied substantially worldwide during the period under study. For example, compared with Australia:
- incidence and mortality were higher in North America, New Zealand and some parts of western Europe
- incidence and mortality were lower in other Western countries (mainly in eastern Europe), and Asia, and lowest in China.
Survival
Currently there are no national data on survival from breast cancer in women in Australia as a whole. In NSW and South Australia, survival was greatest for localised breast cancers. Overall survival from breast cancer in women in Australia, based on data from NSW and South Australia, may be similar to Canada; lower than in the USA and better than in most western European countries. Briefly:
- relative to survival for all women, around 76-77% of women with breast cancer in South Australia in 1977-1994 and NSW in 1987-1991survived five years after diagnosis of breast cancer
- women aged 75 years or older at diagnosis had poorer survival than women at younger ages
- survival five years after diagnosis is much greater if the cancer is found to be localised to the breast at the time of diagnosis than if it has already spread regionally or further.
- breast cancer mortality in recent years was as high in Aboriginal and Torres Strait Islander women as in non-Aboriginal women in Western Australia and the Northern Territory
- breast cancer incidence in Aboriginal and Torres Strait Islander women in these areas 'appeared to be low, although under ascertainment was a likely contributor.
International incidence and mortality
Incidence and mortality varied substantially worldwide during the period under study. For example, compared with Australia:
- incidence and mortality were higher in North America, New Zealand and some parts of western Europe
- incidence and mortality were lower in other Western countries (mainly in eastern
- Europe), and Asia, and lowest in China.
Survival
Currently there are no national data on survival from breast cancer in women in Australia as a whole. In NSW and South Australia, survival was greatest for localised breast cancers. Overall survival from breast cancer in women in Australia, based on data from NSW and South Australia, may be similar to Canada; lower than in the USA and better than in most western European countries. Briefly:
- relative to survival for all women, around 76-77% of women with breast cancer in South Australia in 1977-1994 and NSW in 1987-1991survived five years after diagnosis of breast cancer
- women aged 75 years or older at diagnosis had poorer survival than women at younger ages
- survival five years after diagnosis is much greater if the cancer is found to be localised to the breast at the time of diagnosis than if it has already spread regionally or further.