(ChemotherapyAdvisor) – Adjuvant radiotherapy after local incision for ductal carcinoma in situ (DCIS) reduced risk of local recurrence by 50%, a protective effect observed after 15 years, results of an international trial presented during the 8th European Breast Cancer Conference in Vienna, Austria, on March 22, has found.
Almost one in three women developed a local recurrence in the absence of radiotherapy, said Mila Donker, MD, of the Netherlands Cancer Institute, Amsterdam, The Netherlands, who worked with colleagues from 13 other countries under the auspices of the European Organisation for the Research and Treatment of Cancer (EORTC), Brussels, Belgium. They randomized 1,010 patients with a complete excision of DCIS <5cm to either no further local treatment or radiotherapy (50Gy in 25 fractions to the whole breast) between 1986 and 1996.
After a median follow up of 15.8 years, radiotherapy continued to reduce the risk of a local recurrence (HR=0.52). The local recurrence-free rate was 69% in the local excision alone arm compared with 82% in the arm that received radiotherapy; comparable reductions in the incidence of a DCIS local recurrence (HR=0.49) and an invasive local recurrence (HR=0.49) were observed.
The 15-year cumulative incidence for DCIS recurrence for local excision alone vs. local excision plus radiotherapy was 14.9% vs. 7.5%; for an invasive local recurrence, this was 15.5% vs. 9.8%, respectively.
Differences in local recurrence in both arms did not lead to a difference in distant metastasis (HR=0.99) or death (HR=1.02). Women with a DCIS local recurrence had a similar survival prognosis after the event compared with those without a local recurrence. However, after an invasive local recurrence, their prognosis was significantly worse than nonrecurring patients: HR=5.2 for overall mortality and HR=17.7 for breast cancer-related mortality.
“We found that the majority of the DCIS recurrences occurred within five years of treatment, and that radiotherapy seemed to have a continuous protective effect on DCIS recurrence in the long term,” says Dr. Donker. “However, the protective effect of radiotherapy on the onset of invasive recurrence seemed to be observed mainly in the first five years after treatment, while the risk of developing a recurrence was more or less continuous over the years.”
She added that the study “provides convincing evidence that early treatment does work, and that it can help to avoid the more severe therapies that might be needed at a later stage.” Prognosis and treatment after recurrence in these patients are now being analyzed to address question such as “whether patients who received radiotherapy during the initial treatment have a higher risk of having to undergo a mastectomy after a local recurrence,” Dr. Donker said.
Abstract (Enter “Donker” in the author box to search for abstract No. 217)