A Lancet Oncology study confirms that radiotherapy provides long-term benefits to women with locally excised ductal carcinoma in situ (DCIS), and provides new evidence that tamoxifen helps prevent recurrence as well.

In the study, conducted in the U.K., Australia, and New Zealand, some 1700 women who’d undergone complete local excision of DCIS were randomized to radiotherapy, tamoxifen, both, or neither. During roughly 13 years’ follow-up, there were 376 breast cancer diagnoses.

Radiotherapy conferred a nearly 60% reduction in diagnoses, compared with no radiotherapy; benefits were limited to decreases in ipsilateral invasive cancer and ipsilateral DCIS, with no effects on contralateral disease. In addition, tamoxifen conferred about a 30% reduction in diagnoses, with benefits seen for ipsilateral DCIS and contralateral disease. Tamoxifen did not appear to benefit women who also received radiotherapy.

A commentator, however, says we may be overtreating DCIS, given that larger, higher-grade tumors pose the greatest recurrence risk. He suggests that for lower-risk disease, “the best course might be to monitor for recurrence and offer adjuvant treatment only as needed.”

source: lancet oncology