Women diagnosed with ductal carcinoma in situ (DCIS) are at significantly increased risk of being diagnosed with a subsequent invasive breast cancer according to study findings released today by the Australian Institute of Health and Welfare (AIHW) and National Breast and Ovarian Cancer Centre (NBOCC).
The study, Risk of invasive breast cancer in women diagnosed with ductal carcinoma in situ in Australia between 1995 and 2005, provides the first Australian data on the risk of invasive breast cancer following a diagnosis of DCIS.
'DCIS is a non-invasive tumour arising from, and contained entirely within, a milk duct of the breast. About 1,600 women are diagnosed with DCIS each year in Australia,' said Dr Helen Zorbas, CEO NBOCC.
The study found that women diagnosed with DCIS were about four times more likely to develop a subsequent invasive breast cancer compared with other women of similar age in Australia.
'However, this risk was significantly higher for women who were under 40 years of age when they were diagnosed with DCIS. These women were about 20 times more likely than other Australian women in this age range to develop a subsequent invasive breast cancer,' said Christine Sturrock, Head of the AIHW's Cancer and Screening Unit.
While the risk of invasive breast cancer was higher for women diagnosed with DCIS, these women generally had relatively small invasive breast cancers and these cancers were less likely to have spread to the lymph nodes.
'The practice of placing these women under closer medical surveillance may be responsible for earlier diagnosis of subsequent invasive breast cancers,' Ms Sturrock said.
'This study is an important step forward in our understanding of the risk of invasive breast cancer in Australian women following a diagnosis of DCIS and highlights the importance of ongoing medical surveillance after treatment for DCIS,' said Dr Zorbas.
'Determining exactly which types of DCIS are linked to increased risk of developing subsequent invasive breast cancer remains a key question for future research,' said Dr Zorbas.
