• Objective cognitive function as measured by the CogState battery
  

• Subjective cognitive function as measured by the Cognitive Failures Questionnaire (CFQ)
  
• Psychological distress as measured by the General Health Questionnaire (GHQ)
  
• Fatigue as measured by the Brief Fatigue Inventory (BFI)
  
• Quality of life as measured by the IBCSG QL Core Form
  

OBJECTIVES:

Primary

• Compare cognitive function in postmenopausal women with breast cancer who have received 5 years of adjuvant tamoxifen vs letrozole on protocol IBCSG-1-98.

Secondary

• Compare cognitive function in patients who have received a single hormonal therapy for 5 years vs those who have received that same hormonal therapy for 3 years, having previously received an alternate hormonal therapy for 2 years.
• Compare improvement in cognitive function 1 year after cessation of adjuvant hormonal therapy.
• Compare changes in cognitive function in patients who have received prior adjuvant chemotherapy vs those who have not received adjuvant chemotherapy.
• Assess the relationship between objective and subjective measures of cognitive function, including specific cognitive domains.
• Assess the relationship between cognitive function and psychological distress, fatigue, and quality of life.

OUTLINE: This is a longitudinal, multicenter study.

Patients undergo cognitive function testing and complete self-reported questionnaires regarding cognitive ability, quality of life, fatigue, and psychosocial status during the fifth year of adjuvant hormonal therapy on protocol IBCSG-1-98 and then during the sixth year* (post randomization on protocol IBCSG-1-98) (i.e., after completion of adjuvant hormonal therapy).

NOTE: *Patients who receive extended letrozole, hormone replacement therapy, or other endocrine therapy beyond 5 years do not undergo the 6-year assessment.

PROJECTED ACCRUAL: A total of 148 patients will be accrued for this study.