Identifying breast cancer patients most likely to benefit from aromatase inhibitor therapy after adjuvant radiation and tamoxifen

Cancer. 2006 Dec 1;107(11):2552-8. doi: 10.1002/cncr.22291.

Abstract

Background: The purpose of the current study was to examine patient selection for an aromatase inhibitor in breast cancer patients who were free from adverse events 5 years after treatment with tamoxifen.

Methods: In all, 471 women were treated with breast-conserving surgery, axillary lymph node dissection, and radiation. Eligibility included T1-2 disease, tamoxifen use, follow-up of >/=5 years, no prior breast cancer, and freedom from all events at 5 years of follow-up. Patients treated with chemotherapy more often had T2 disease and positive lymph nodes, and were aged <60 years compared with patients treated with tamoxifen alone. No patient during the period of the current study (1982-1999) received an aromatase inhibitor. The median follow-up was 8.25 years.

Results: There were 36 events: 10 contralateral breast cancers (CBCs) and 26 recurrences (8 local, 1 regional, and 17 distant). The 10-year risk of locoregional recurrence was 2.5%, the 10-year risk of CBC was 3.6%, and the 10-year risk of distant metastasis was 4.4%. The event-free survival rate for all patients was 93%. Only >/=4 positive lymph nodes and premenopausal status were found to be independent variables for decreased event-free survival on multivariate analysis. The overall survival rate was 89%. Only younger age and lower lymph node status were found to be significant predictors of improved overall survival.

Conclusions: In the current study, a 40% reduction in recurrence/CBC with the addition of an aromatase inhibitor after 5 years of tamoxifen treatment would have had a marginal benefit of 1% to 2%. Women who were premenopausal and patients with >/=4 positive lymph nodes would have the greatest absolute benefit of >3% in the 10-year event-free survival rate from extended therapy. The decision needs to be individualized for patients aged >/=60 years based on their initial lymph node status and the presence of comorbidities that could lower their 5-year life expectancy.

MeSH terms

  • Adult
  • Aged
  • Aged, 80 and over
  • Aromatase Inhibitors / therapeutic use*
  • Breast Neoplasms / drug therapy*
  • Breast Neoplasms / metabolism
  • Breast Neoplasms / radiotherapy
  • Breast Neoplasms / surgery
  • Disease-Free Survival
  • Female
  • Follow-Up Studies
  • Humans
  • Middle Aged
  • Radiotherapy, Adjuvant
  • Receptors, Estrogen / biosynthesis
  • Receptors, Progesterone / biosynthesis
  • Survival Rate
  • Tamoxifen / therapeutic use
  • Treatment Outcome

Substances

  • Aromatase Inhibitors
  • Receptors, Estrogen
  • Receptors, Progesterone
  • Tamoxifen