Radiotherapy After Local Excision for DCIS Reduces Long-Term Risk of Local Recurrence
As reported in Journal of Clinical Oncology, Mila Donker, MD, of the Netherlands Cancer Institute, and colleagues analyzed the effects of adjuvant radiotherapy after local excision for ductal carcinoma in situ (DCIS) on long-term risk for local recurrence and survival in patients from the EORTC 10853 trial. Radiotherapy was associated with reduced 15-year risks for local recurrence overall and invasive local recurrence.
Radiotherapy Reduced Risk of Local Recurrence
In the EORTC 10853 trial, 1,010 women with complete local excision of DCIS < 5 mm were randomly assigned to no further treatment (n = 503) or radiotherapy (n = 507). Median follow-up was 15.8 years. The 15-year local recurrence–free rate was 82% in the radiotherapy group vs 69% in the local excision group (hazard ratio [HR] = 0.52, P < .001). The 15-year pure DCIS local recurrence–free rate was 92% in the radiotherapy group vs 84% in the local excision group (HR = 0.49, P = .003), and invasive local recurrence–free rates were 90% vs 84% (HR = 0.61, P = .007). Radiotherapy was associated with reduced risk of invasive local recurrence in all subgroups examined; in the subgroup with the lowest risk of invasive local recurrence (clinging/micropapillary DCIS group), radiotherapy reduced the risk of invasive local recurrence from 12.4% to 5.1%.
Risk of local recurrence was highest during the first 5 years, with rates of 4.0% per year in the local excision group and 2.0% per year in the radiotherapy group; rates decreased to 2.0% and 1.2% in the next 5 years and to 1.3% and 0.6% from 10 years on. A similar trend was observed for DCIS local recurrence. The highest risk of invasive recurrence was also during the first 5 years with no difference between groups being observed after 5 years.
No Survival Differences
The differences in overall local recurrence between the radiotherapy and local excision groups were not associated with differences in 15-year breast cancer–specific survival (96% vs 95%, HR = 1.07, P = .814) or overall survival (90% vs 88%, HR = 1.02, P = .931).
No differences in breast cancer–specific survival (HR = 0.65; 95% confidence interval = 0.16–2.71) or overall survival (HR = 1.19, 95% CI = 0.59–2.37) were observed for women who developed DCIS recurrence compared with those without recurrence. Patients with invasive local recurrence had significantly worse breast cancer–specific survival (HR = 17.66, 95% CI = 8.86–35.18) and overall survival (HR = 5.17, 95% CI = 3.09–8.66) compared with patients without recurrence.
Patients in the radiotherapy group had a lower overall salvage mastectomy rate after local recurrence (13% vs 19%).
The investigators concluded: “At 15 years, almost one in three nonirradiated women developed a local recurrence after local excision for DCIS. Radiotherapy reduced this risk by a factor of 2. Although women who developed an invasive recurrence had worse survival, the long-term prognosis was good and independent of the given treatment.”
Nina Bijker, MD, of the Academic Medical Center in Amsterdam, is the corresponding author for the Journal of Clinical Oncology article.
The study was supported by a donation from the Kankerbestrijding/KWF from the Netherlands through the EORTC Charitable Trust.
The content in this post has not been reviewed by the American Society of Clinical Oncology, Inc. (ASCO®) and does not necessarily reflect the ideas and opinions of ASCO®.
