PITTSBURGHThe 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
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 DCISregardless of
margin sta-tusthey are using their definition of clear margins
(margins that are not transected), he said.
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.
Its clear that tamoxifen and radiation therapy, plus
lumpectomy, worked overall in protocol B-24, he said, but
the study didnt 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.