Radiation therapy and tamoxifen both reduce the risk of invasive ipsilateral breast tumour recurrence in patients who have received breast-conserving surgery for ductal carcinoma in situ (DCIS), reports the Journal of the National Cancer Institute. The US study showed tht the best outcomes were achieved for patients receiving lumpectomy, radiotherapy and tamoxifen.

The prevalnce of ductal carcnma in situ (DCIS) has increased over the last 20 years largely as a result of increased use of mammographic screening. While satisfactory local control has been reported following lumpectomy with similar survival statistics to mastectomy, there have been concerns over the subsequent risk of ipsilateral breast tumour recurrences with lumpectomy.

In the current study Irene Wapnir and colleagues, from Stanford University School of Medicine (Stanford, CA), evaluated invasive ipsilateral breast tumour recurrence (IBTR) and its influence on survival among participants in two randomised trials for DCIS, the National Surgical Adjuvant Breast and Bowel Project (NSABP) B-17 and B-24 trials. Together these studies represent the largest prospective evaluation of breast conserving therapies for DCIS to date.

In the B-17 trial between October 1985 and December 1990 813 patient with localised DCIS were reandomly assigned to lumpectomy only (n=403) or lumpectomy followed by radiotherapy (n=410).

In the B-24 trial between May 1991 and and April 1994, 1799 patients with localised DCIS were randomly assigned to lumpectomy and radiotherapy plus placebo (n=900) or to lumpectomy and radiotherapy plus tamoxifen (n=899).

Results of the B17 trial show that radiation reduced invasive IBTR by 52% in the group receiving radiotherapy compared to the group receiving lumpectomy only (HR 0.48, 95% CI 0.33-0.69, P<.001).

Results of the B-24 trial show that receiving lumpectomy, radiotherapy and tamoxifen reduced invasive IBTR by 32% compared to lumpectomy, radiotherapy and placebo (HR 0.68, 95% CI 0.49 t0 0.95, P=.025).

The 15 year cumulative incidence of invasive IBTR was 19.4% for patients assigned to lumpectomy, 8.9% for patients assigned to lumpectomy and radiotherapy, 10% for lumpectomy , radiotherapy and placebo, and 8.5% for lumpectomy, radiotherapy and tamoxifen.

The 15 year cumulative incidence of all contralateral breast cancer was 10.3% for patients assigned to lumpectomy only, 10.2% for lumepctomy and radiotherapy, 10.8% for lumpectomy, radiotherapy and placebo, and 7.3% for lumpectomy, radiotherapy and tamoxifen.

Among all the patietns in the study the 15 year cumulative incidence of breast cancer death was 3.1% for lumpectomy, 4.7% for lumpectomy and radiotherapy,, 2.7% for lumpectomy, radiotherapy and placebo, and 2.3% for lumpectomy, radiotherapy and tamoxifen.

"We believe that these long-term findings of NSABP B-17 and B-24 demonstrate that lumpectomy and adjuvant therapies are effective modalities in the treatment of DCIS," conclude the authors, adding that the results suggest strong caution in considering the use of prophylactic surgery as a means to prevent breast cancer mortality among DCIS patients.

"It is highly likely that current breast imaging practices, improvements in margin assessments, and advances in adjuvant treatments will continue to reduce the incidence of invasive recurrences after DCIS."

Article: I L Wapnir JJ Dignam, B Fisher. Long-term outcomes of invasive ipsilateral breast tumor recurrences after lumpectomy in NSABP B-17 and B-24 randomised clinical trials for DCIS. J Natl Cancer Inst 2011; 103:478-488.