For early-stage breast cancer patients diagnosed with ductal carcinoma in situ (DCIS), radiotherapy treatments following a lumpectomy helped protect against cancer recurrence for at least 15 years, according to a presentation made yesterday at the European Breast Cancer Conference (EBCC) in Vienna.
The addition of radiotherapy reduced ipsilateral breast cancer recurrence by 50% among a group of more than 1,000 patients enrolled in a long-term, multinational, randomized clinical trial. This trial represents one of the longest clinical trials following the outcomes of one of the largest groups of patients with DCIS in the world.
Between1986 and 1996, 1,010 women enrolled in the study, at which time they underwent breast conservation surgery to remove a breast tumor smaller than 5 cm. They were then randomized to receive either 50 Gy of radiotherapy administered in 25 fractions to the whole breast or not to receive any additional treatment. Cancer treatment centers in Belgium, France, Italy, and the Netherlands participated, following the women for a median of 15.8 years.
Almost one in three women who did not receive radiotherapy treatment developed a local recurrence, reported Dr. Mila Donker, a research physician in the department of surgical oncology at the Netherlands Cancer Institute at Antoni van Leeuwenhoek Hospital. The 15-year cumulative incidence for DCIS recurrence in the surgery-only group was 14.9%, compared with 7.5% for the combined treatment group. Invasive cancer recurrence rates were also similar, with the surgery-only group experiencing 15.5% recurrence, compared with 9.8% for the combined group.
"We found that the majority of DCIS recurrences occurred within five years of treatment, and that radiotherapy treatment seemed to have a continuous protective effect on DCIS recurrence in the long term," she said. Radiotherapy treatment only protected women for the first five years of treatment from an invasive breast cancer recurrence, Donker and colleagues noted.
Although no survival difference was identified between the two treatment groups, women who experienced an invasive recurrence had a significantly worse survival prognosis compared to women who either had a DCIS recurrence or no recurrence at all.
DCIS cases in Europe now account for about one-fourth of all new breast cancer diagnoses. The current recommended treatment protocol of breast conservation surgery followed by radiotherapy has been criticized as overtreatment for a lesion that may not have developed into a life-threatening cancer.
"Our study provides convincing evidence that early treatment does work, and that it can help to avoid the more severe therapies that may be needed at a later stage," Donker noted.
