Breast cancer in NSW women: a shift in tumour size.
OBJECTIVE
To determine whether there has been an increase in the proportion of small (< 1 cm in size) and localised breast cancers in women aged 50-69 (the group actively recruited to mammographic screening) compared with women aged 40-49.


METHODS
Cases of invasive breast cancer in women aged 40-69 notified to the NSW Central Cancer Registry in 1986, 1989 and 1992 were included. Tumour sizes were determined from histopathology reports.


RESULTS
A higher percentage of breast cancers were under 1 cm in size in 1992 (10%) than in 1986 and 1989 (7%). The increase in the percentage of small breast cancers was statistically significant in women aged 50-69 (chi 2 for linear trend, 7.9; P = 0.005) but not in those aged 40-49 (chi 2 for linear trend, 2.5; P = 0.12). Slightly more than half the breast cancers (53%) in 1992 were localised to the breast, representing an increase from 49% in both 1986 and 1989. This increase was also statistically significant in women aged 50-69 (chi 2 for linear trend, 3.9; P = 0.05) but not in those aged 40-49 (chi 2 for linear trend, 1.4; P = 0.24).


CONCLUSIONS
Breast cancers in 1986, 1989 and 1992 showed a moderately strong shift to smaller tumours and localised disease in women aged 50-69. As women of this age group were targeted by mammographic screening, the widespread availability of mammography may explain this shift.
Kricker
A
A
Cancer Epidemiology Research Unit, NSW Cancer Council, Sydney.
Høyer
A P
AP
McCredie
M
M
Porter
L A
LA
D000328:Adult; D017677:Age Distribution; D000368:Aged; D001940:Breast / Q000473:pathology*; D001943:Breast Neoplasms / Q000175:diagnosis / Q000453:epidemiology / Q000473:pathology*; D005260:Female; D006801:Humans; D015994:Incidence; D008327:Mammography; D008875:Middle Aged; D009517:New South Wales / Q000453:epidemiology; D013021:South Australia / Q000453:epidemiology