Radiotherapy and tamoxifen after mastectomy in postmenopausal women – 20 year follow-up of the South Sweden Breast Cancer group randomised trial SSBCG II:I

Abstract 

Aims

To evaluate long-term effects of radiotherapy and tamoxifen after mastectomy on recurrence and survival in stage II breast cancer.

Methods

A randomised phase III study with three treatment alternatives. (1) Radiotherapy 50Gy/25 fractions to chest wall and regional lymph nodes (RT). (2) Radiotherapy and tamoxifen 30mg/day for one year (RT+tam) and 3. Tamoxifen (tam).

Results

724 postmenopausal women were included between 1978 and 1985 and the trial was close to population based. Follow-up for survival was 23 years. Locoregional recurrences were reduced from 18.5% in the tam arm to 5.3% in the RT+tam arm. Overall mortality at 20 years was 71% in the RT arm, 68% in the RT+tam arm and 62% in the tam arm. The difference between RT+tam and tam was not significant except in the receptor positive subgroup in favour of non-irradiated patients (p=0.047). The cumulative incidence of systemic disease at 20 years was lower in the RT+Tam arm than in the RT arm, 40% versus 50% (p=0.047).

Conclusion

Postmastectomy radiotherapy significantly reduced loco-regional recurrences, but overall survival was not improved. At 20 years, a lower mortality was recorded for non-irradiated patients treated with tam.

Keywords: Breast cancer, Mastectomy, Radiotherapy, Local recurrence, Mortality, Long-term, Tamoxifen