Experts are calling for a reassessment of the standard of care for women with ductal carcinoma in situ (DCIS) after a large study has shown no reduction in breast cancer-specific mortality in patients treated aggressively with radiotherapy (RT) following lumpectomy or with unilateral mastectomy.
In patients with DCIS who underwent RT after lumpectomy (n=42,250), the rate of breast cancer-specific mortality at 10 years was 0.8 percent – a nonsignficiant difference compared with 0.9 percent for those who underwent lumpectomy alone (n=19,762) (adjusted hazard ratio [HR], 0.81; p=0.10). [JAMA Oncol 2015, doi: 10.1001/jamaoncol.2015.2510]
In patients who underwent unilateral mastectomy for DCIS (n=19,515), the 10-year rate of breast cancer-specific mortality was 1.3 percent – a nonsignficiant difference compared with lumpectomy (adjusted HR, 1.20; p=0.11).
The findings are surprising because early treatment of DCIS has been presumed to reduce cancer incidence and mortality.
In the observational study on 108,196 women diagnosed with DCIS between 1988 and 2011, aggressive treatment was found to reduce the 10-year risk of ipsilateral invasive recurrence.
“For patients who had a lumpectomy, RT reduced the risk of ipsilateral invasive recurrence at 10 years from 4.9 percent to 2.5 percent [adjusted HR, 0.47; p<0.001],” the investigators reported. “Similarly, patients who underwent unilateral mastectomy had a lower risk of ipsilateral invasive recurrence at 10 years than patients who underwent lumpectomy [1.3 vs 3.3 percent; adjusted HR, 0.81; p<0.001].”
“Surprisingly, the majority of women with DCIS in the cohort who died of breast cancer did not experience an invasive ipsilateral or contralateral recurrence prior to death,” they pointed out.
Overall, the rate of breast cancer-specific mortality was low – 3.3 percent at 20 years. However, patients diagnosed with DCIS before 35 years of age had a higher risk of death from breast cancer at 20 years compared with those diagnosed at an older age (7.8 vs 3.2 percent; HR, 2.58; p<0.001).
“The current analysis fuels a growing concern that we should rethink our strategy for the detection and treatment of DCIS,” wrote editorialists Dr. Laura Esserman and Dr. Christina Yau of the University of California, San Francisco, CA, US. “RT should not be routinely offered after lumpectomy for DCIS lesions that are not high risk because it does not affect mortality.” [JAMA Oncol 2015, doi: 10.1001/jamaoncol.2015.2607]
High-risk cases, including women <40 years of age with symptomatic DCIS and women with hormone receptor-negative or HER2-positive DCIS, should continue to be treated according to today’s aggressive standards, they noted.