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Radiotherapy after local excision decreased breast cancer recurrence
Adjuvant radiotherapy after local excision for ductal carcinoma in situ reduced the incidence of in situ and invasive local recurrence, according to study results.
“Although reduction was seen in all subgroups, it did not affect OS,” the researchers wrote. “However, patients with invasive local recurrence had a significantly worse survival compared with patients without local recurrence, and thus, invasive local recurrence should be prevented.”
Researchers set out to assess the long-term risk for developing local recurrence and the impact it may have on survival after local treatment for ductal carcinoma in situ.
The analysis included 1,010 women treated between 1986 and 1996. Of them, 503 underwent local excision and no further treatment. Researchers assigned the other 507 women to receive radiotherapy after local excision.
Median follow-up was 15.8 years.
The use of radiotherapy reduced risk for any local recurrence by 48% (HR=0.52; 95% CI, 0.40-0.68). The 15-year local recurrence-free rate was 82% among patients who underwent radiotherapy compared with 69% among those who did not. The 15-year invasive local recurrence-free rate was 90% among patients who underwent radiotherapy and 84% among those who did not (HR=0.61; 95% CI, 0.42-0.87).
Women with invasive local recurrence demonstrated significantly worse breast cancer-specific survival (HR=17.66; 95% CI, 8.86-35.18) and OS (HR=5.17; 95% CI, 3.09-8.66) compared with women who did not experience local recurrence.
The overall salvage mastectomy rate after local recurrence was lower in women who underwent radiotherapy after local excision (13% vs. 19%).
“Although women who developed an invasive recurrence had worse survival, the long-term prognosis was good and independent of the given treatment,” the researchers wrote. “On the basis of the results of this trial, a subgroup of patients in whom radiotherapy can be withheld could not be identified.”
Disclosure: The researchers report no relevant financial disclosures.Perspective
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The 15-year update of the EORTC 10853 trial was recently published in the Journal of Clinical Oncology.
Between 1986 and 1996, 1,010 women with ductal carcinoma in situ (DCIS) were randomly assigned to local excision (LE) with or without radiation (RT). The 15-year local recurrence-free rate was 69% in the excision alone group and improved to 82% with the addition of radiation. Nearly 1 in 3 patients had a local recurrence with local excision alone, and the rate decreased by 50% with the addition of radiation. This benefit of radiation was seen regardless of age, use of tamoxifen, tumor size, grade, comedonecrosis or margin status.
Although there was no difference in OS between the two groups, the trial was not powered to measure this. Following a local recurrence, more patients underwent a salvage mastectomy if they had been previously radiated. Overall, however, mastectomy rates were lower in the LE plus RT group (13%) vs. LE alone (19%).
Because survival after DCIS is excellent regardless of the type of treatment, in an era of cost containment, the question of overdiagnosis and overtreatment arises. Although there is active ongoing investigation in developing prediction tools that can help identify the subgroup of patients who do not require radiation, the long-term results of EORTC 10853 confirm that the current standard of care for DCIS remains local excision followed by radiation.
Perspective
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Donker and colleagues report 15-year outcomes from the EORTC 10853 randomized, controlled trial for the treatment of ductal carcinoma in situ (DCIS) demonstrating a durable effect of radiotherapy for reducing local invasive and DCIS recurrences when delivered after local excision. The magnitude of local recurrence reduction (HR=0.52) at a median of 15.8 years post-radiotherapy is comparable to that seen at 10.5 years (HR=0.53) and slightly larger than 5 years (HR=0.62). Importantly, there were no excess contralateral breast cancers or non-breast cancer deaths in the radiotherapy arm. The DCIS patients enrolled on the EORTC 10853 trial are "high risk" by today’s standards — about 27% presented with a palpable mass, 36.6% had poor histology, 74.6% had involved/close or unknown surgical margins, and none had tamoxifen. In current practice, even better local control outcomes can be expected with radiotherapy, given the close attention to surgical margins, tamoxifen use and mammographic detection.
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