Long-term benefits of 5 years of tamoxifen: 10-year follow-up of a large randomized trial in women at least 50 years of age with early breast cancer

J Clin Oncol. 2011 May 1;29(13):1657-63. doi: 10.1200/JCO.2010.32.2933. Epub 2011 Mar 21.

Abstract

Purpose: The Cancer Research UK "Over 50s" trial compared 5 and 2 years of tamoxifen in women with early breast cancer. Results are reported after median follow-up of 10 years.

Patients and methods: Between 1987 and 1997, 3,449 patients age 50 to 81 years with operable breast cancer who had been taking 20 mg of tamoxifen for 2 years were randomly assigned to either stop or continue for an additional 3 years, if they were alive and recurrence free. Data on recurrences, new tumors, deaths, and cardiovascular events were obtained (April 2010).

Results: There were 1,103 recurrences, 755 deaths as a result of breast cancer, 621 cardiovascular (CV) events, and 236 deaths as a result of CV events. Fifteen years after starting treatment, for every 100 women who received tamoxifen for 5 years, 5.8 fewer experienced recurrence, compared with those who received tamoxifen for 2 years. The risk of contralateral breast cancer was significantly reduced (hazard ratio, 0.70; 95% CI, 0.48 to 1.00). Among women age 50 to 59 years, there was a 35% reduction in CV events (P = .005) and 59% reduction in death as a result of a CV event (P = .02); in older women, the effect was much smaller and not statistically significant.

Conclusion: Taking tamoxifen for the recommended 5 years reduces the risk of recurrence or contralateral breast cancer 15 years after starting treatment. It also lowers the risk of CV disease and death as a result of a CV event, particularly among those age 50 to 59 years. Women should therefore be encouraged to complete the full course. Although aromatase inhibitors improve disease-free survival, tamoxifen remains a cheap and highly effective alternative, particularly in developing countries.

Publication types

  • Multicenter Study
  • Randomized Controlled Trial
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Aged
  • Aged, 80 and over
  • Antineoplastic Agents, Hormonal / administration & dosage*
  • Aromatase Inhibitors / administration & dosage*
  • Breast Neoplasms / drug therapy*
  • Breast Neoplasms / mortality
  • Cardiovascular Diseases / epidemiology
  • Cardiovascular Diseases / mortality
  • Chemotherapy, Adjuvant
  • Disease-Free Survival
  • Drug Administration Schedule
  • Female
  • Follow-Up Studies
  • Humans
  • Middle Aged
  • Neoplasms, Second Primary / epidemiology
  • Recurrence
  • Tamoxifen / administration & dosage*

Substances

  • Antineoplastic Agents, Hormonal
  • Aromatase Inhibitors
  • Tamoxifen