DCIS Life History Reveals Mortality Risk Without Invasive Disease

Ductal carcinoma in situ has a low mortality rate but shares features with invasive breast cancer

medwireNews: Ductal carcinoma in situ (DCIS) has a low rate of breast cancer-specific mortality but the disease shares features with small, invasive breast cancer, suggests research published in JAMA Oncology.

The 20-year breast cancer-specific mortality rate in the Surveillance, Epidemiology, and End Results cohort of 108,196 DCIS patients was just 3.3%, but 54.1% of patients who died from breast cancer did so without developing invasive breast cancer in the ipsilateral or contralateral breast.

“Some cases of DCIS have an inherent potential for distant metastatic spread”, say lead author Steven Narod, from Women’s College Hospital in Toronto, Ontario, Canada, and team.

“It is therefore appropriate to consider these as de facto breast cancers and not as preinvasive markers predictive of a subsequent invasive cancer”, they advise.

Multivariate analysis identified several risk factors for breast cancer-specific mortality, including tumour size and grade.

Black women were significantly more likely to die than non-Hispanic White women (7.0 vs 3.0%, hazard ratio [HR]=2.55), as were women diagnosed with DCIS before the age of 35 years compared with patients aged 60 to 69 years at diagnosis (7.8 vs 3.7%, HR=1.88). By contrast, Oestrogen receptor (ER)-positive patients were significantly less likely die from breast cancer than ER-negative patients (HR=0.61).

DCIS patients who later developed ipsilateral invasive breast cancer were 18.1 times more likely to die from breast cancer than those who did not, Steven Narod et al observe.

But while both mastectomy and lumpectomy, followed by radiotherapy, significantly reduced the risk of breast cancer recurrence, neither treatment significantly reduced the 10-year rate of breast cancer-specific death.

Editorialists Laura Esserman and Christina Yau, both from the University of California, San Francisco, USA, observe that the rates of ipsilateral and contralateral invasive breast cancer after DCIS were comparable, at 5.9% versus 6.2%, suggesting that “we need to think about DCIS as if it were a risk factor like atypia” rather than a local marker.

DCIS may “represent an opportunity to alter the environment of the breast” via changing habits such as diet, alcohol intake, exercise and postmenopausal hormone therapy, they suggest.

Laura Esserman and Christina Yau also recommend that “[g]iven the low breast cancer mortality risk, we should stop telling women that DCIS is an emergency and that they should schedule definitive surgery within 2 weeks of diagnosis.”

Nevertheless, they emphasise the need for further research and testing of targeted approaches for patients with large, high grade, ER-negative, HER2-positive DCIS, especially in Black women and those diagnosed at a young age.

References

Narod SA, Iqbal J, Giannakeas V, et al. Breast cancer mortality after a diagnosis of ductal carcinoma in situ. JAMA Oncol; Advance online publication 20 August 2015. doi:10.1001/jamaoncol.2015.2510

Esserman L, Yau C. Rethinking the standard for ductal carcinoma in situ treatment. JAMA Oncol; Advance online publication 20 August 2015. doi:10.1001/jamaoncol.2015.2607

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