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WCH study identifies mortality risk factors linked to very early stage breast cancer

Ductal carcinoma in situ (DCIS) – a very early stage of breast cancer sometimes called stage 0 breast cancer – may have more in common with invasive forms of cancer than previously thought, including the potential to spread to other organs.

Despite being diagnosed at such an early stage, a small number of women with DCIS eventually die of breast cancer. A team of Women’s College Hospital (WCH) researchers determined that women with DCIS had almost double the risk of dying of breast cancer as women in the general population. Ten years after diagnosis, about one in 100 women (1.1 per cent) diagnosed with DCIS had died of breast cancer. At 20 years, the number rose to 3.3 per cent.

The researchers, led by Dr. Steven Narod, a scientist at Women’s College Research Institute and professor at the Dalla Lana School of Public Health at the University of Toronto, also identified several factors linked to higher risk of breast cancer death in women with DCIS. These included age at diagnosis, ethnicity, and breast cancer recurrence. Although very few women in the study had DCIS before age 35, those who were diagnosed at that age had significantly higher breast cancer mortality rates: 17 times higher than the general population. The researchers also found that black women with DCIS were at greater risk for dying of breast cancer compared to white women.

Women who develop a second breast cancer in the same breast as their DCIS diagnosis have a much higher risk of dying of breast cancer than those who do not. However, one of the study’s most important findings was that in some cases, women diagnosed with DCIS who never developed a second breast cancer still died of breast cancer. The researchers noted that this suggests DCIS may have more in common with later stage cancers that previously believed, and DCIS can potentially spread to other organs.

The study also found that treatments such as radiation therapy and mastectomy reduced recurrence of breast cancer in DCIS patients, but did not reduce mortality rates.

“Despite being diagnosed at a very early stage, and despite undergoing treatments such as radiation, lumpectomy or mastectomy, a small number of women with DCIS later died of breast cancer,” Dr. Narod said. “This research changes our understanding of this condition. It suggests that some cases of DCIS have the potential to metastasize.” 

DCIS accounts for about one in five breast cancers found through screening mammograms. Dr. Narod’s team studied data on 108,196 women in the United States who were diagnosed with DCIS from 1988 to 2011, following each woman for an average of 7.5 years.

The research was published in JAMA Oncology on August 20, 2015.

 

 

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  • A publication of:
  • Women's College Hospital