For women with ductal carcinoma in situ (DCIS), adding radiation therapy and/or tamoxifen to treatment lowers the risk of the recurrence of aggressive cancer, doctors at Allegheny General Hospital and the National Surgical Adjuvant Breast Bowel Project revealed in the Journal of the National Cancer Institute.

DCIS is the most common form of breast cancer.

Head researcher, Thomas Julian, MD, said:

"Women with DCIS can be reassured that they are not being overtreated when their doctor prescribes radiation therapy in addition to a lumpectomy. A clear benefit is shown in preventing tumor recurrence. This study, following a group of women over 15 years, provides invaluable information on the progression of this disease."

DCIS currently accounts for approximately 25% of all new breast cancers. Its prevalence has grown over the last twenty years, mainly thanks to increased use of mammography.

DCIS is when abnormal cells multiply and grow within a milk duct. The cancer needs to be treated before it spreads.

Previous trials carried out by the National Surgical Adjuvant Breast Bowel Project (NSABP) revealed similar rates of survival for those who had breast conserving surgery instead of a mastectomy. However, there has been continued concern about the chances of I-IBTR (Ipsilateral Breast Tumor Recurrence), a type of cancer recurrence with a much higher risk of death. There was also concern regarding using additional therapies.

Female participants with DCIS were followed for between 13.5 to 17 years in two previous NSABP trials. I-IBTR went down 52% in those who received a lumpectomy combined with radiotherapy, compared to those who only had the surgery. When tamoxifen was also added to patients with estrogen receptor positive DCIS, I-IBTR risk fell 32% compared to those who had a lumpectomy and radiotherapy only.

Over a 15-year period, I-IBTR incidence was:
  • 19.4% for the lumpectomy only patients
  • 8.9% for those receiving both lumpectomy plus radiotherapy
  • 8.5% for the triple combination - lumpectomy, radiotherapy, and tamixofen
  • 10% for those who received a lumpectomy, radiation, plus a placebo
Dr. Julian said:

"I-IBTR increases the risk of a breast cancer-related death, but the good news is that use of radiation therapy and tamoxifen (in estrogen receptor positive DCIS) reduce that risk for women with DCIS and the overall long-term prognosis is excellent for women who undergo breast-conserving surgery."

"Long-Term Outcomes of Invasive Ipsilateral Breast Tumor Recurrences After Lumpectomy in NSABP B-17 and B-24 Randomized Clinical Trials for DCIS"
Irene L. Wapnir, James J. Dignam, Bernard Fisher, Eleftherios P. Mamounas, Stewart J. Anderson, Thomas B. Julian, Stephanie R. Land, Richard G. Margolese, Sandra M. Swain, Joseph P. Costantino and Norman Wolmark
JNCI J Natl Cancer Inst (2011) doi: 10.1093/jnci/djr027

Written by Christian Nordqvist