Tamoxifen added to radiotherapy and surgery for the treatment of ductal carcinoma in situ of the breast: a meta-analysis of 2 randomized trials.

BACKGROUND: Surgical excision with adequate margins is the treatment of choice for ductal, in situ carcinoma of the breast (DCIS). The addition of radiotherapy (RT) halved local in situ and invasive recurrence. The purpose of our meta-analysis is to evaluate the reduction in recurrence (in situ or invasive) with the addition of tamoxifen (T), in particular in patients with DCIS treated with surgery+RT.

PATIENTS AND METHODS: The eligible studies (NSABP-B24 and UK ANZ DCIS trials) included prospective, randomized, controlled trials in which the addition of T had been compared with surgery+RT without T in women with DCIS of the breast. Relative risks (RRs) with 95% confidence intervals (CIs) were calculated for both in situ and invasive recurrence (local and controlateral).

RESULTS: Tamoxifen does not reduce breast cancer-specific or overall mortality when added to loco-regional therapy for DCIS of the breast (surgery plus or minus RT). Tamoxifen reduces overall breast cancer recurrence by 29% in all patients and by 33% in those treated with both surgery and RT. Only ipsilateral invasive (RR 0.61 [95% CI 0.41, 0.92]; p=0.02) and controlateral in situ relapses (RR 0.40 [95% CI 0.16, 0.96]; p=0.04) are significantly lowered when T is added to RT. Tamoxifen seems to exert a local synergistic effect with RT. Both young and older women (< and >50 years) achieve some benefit from the addition of T (RR 0.6 and 0.74, respectively).

CONCLUSION: The addition of T to surgery and RT for DCIS of the breast reduces the risk of local invasive and controlateral in situ relapses, but not the survival. The benefit is independent of age. In conclusion, surgery associated with RT and T is the treatment of choice for patients with (estrogen-receptor positive) DCIS of the breast.