Tamoxifen After Surgery/RT Decreases Local Recurrence Risk in DCIS Patients

PITTSBURGH—The addition of tamoxifen (Nolvadex) to lumpectomy plus radiation therapy in women with ductal carcinoma in situ (DCIS) significantly reduces the 5-year cumulative incidence of recurrent invasive ipsilateral breast tumors, Norman Wolmark, MD, chairman of the National Surgical Adjuvant Breast and Bowel Project (NSABP), said at the San Antonio Symposium.

Dr. Wolmark reported the results of protocol B-24, in which 1,804 patients with DCIS treated with breast-conserving surgery and radiation therapy were randomized to receive either tamoxifen or placebo for 5 years.

Results at average follow-up of 62 months show a significant decrease in the incidence of invasive ipsilateral breast cancer recurrence with use of tamoxifen (2.1% vs 3.4% with placebo) and a significant 5% reduction of all first breast cancer events (including contralateral breast cancer) (8.8% vs 13% with placebo) (see Table).

Dr. Wolmark told Oncology News International that “the results of this study should come as no surprise. Tamoxifen has been shown to decrease the incidence of ipsilateral breast tumor recurrence in invasive breast cancer, and the observation that tamoxifen lowers the incidence of contralateral disease is consistent with the findings from the NSABP chemoprevention trial.”

He added that “tamoxifen is expected to become a standard adjunct for the treatment of DCIS.”

A Word of Caution

In an interview, Melvin Silverstein, MD, director of the Lee Breast Center at the Norris Cancer Center of the University of Southern California, cautioned that, in his opinion, the study has not determined that all DCIS patients should receive adjuvant tamoxifen. In his opinion, patients who achieve wide margins (“greater than 10 mm in every direction”) may not benefit from additional treatment.

“When the NSABP states that there is a significant benefit from use of tamoxifen plus radiation therapy in DCIS—regardless of margin sta-tus—they are using their definition of clear margins (margins that are not transected),” he said.

Prognostic Index

Dr. Silverstein has long been an advocate of using a prognostic index incorporating tumor grade, size, and margin width to determine which DCIS patients can safely have lumpectomy without radiation and which patients might be better served by mastectomy.

“It’s clear that tamoxifen and radiation therapy, plus lumpectomy, worked overall in protocol B-24,” he said, “but the study didn’t measure margins, and we would like to fine tune which patients really need tamoxifen therapy based on margin width.”

Nonetheless, Dr. Silverstein said he was “excited” with the preliminary results of B-24. “The study continues to show just how remarkable tamoxifen is in preventing both breast cancer recurrences and new breast cancers,” he commented.