Trial Information

SOLE Estrogen Substudy (SOLE-EST) - Investigating Changes in Estrogen Levels and Grip Strength for Patients Participating in the SOLE Trial

OBJECTIVES:

Primary

- To determine the serum level of estrogens (Estradiol [E2], Estrone [E1], and Estrone
Sulphate [E1S] and sex hormone binding globulin [SHBG]) in postmenopausal women with
prior endocrine-responsive, node-positive, resectable breast cancer completing 4 to 6
years of adjuvant endocrine therapy and enrolled on clinical trial IBCSG-35-07
receiving letrozole.

- To determine the degree of recovery of E2, E1, and E1S during the 3-month letrozole-off
gap.

Secondary

- To determine the association between estrogen level changes and the clinical outcomes
of toxicity and quality of life.

- To determine the effect of prior adjuvant endocrine therapy, age, body mass index, and
type of menopause on estrogen levels.

- To determine the variability of estrogen level changes and its association with
germline single nucleotide polymorphisms.

- To examine changes in grip-strength score.

OUTLINE: This is a multicenter study.

All patients undergo blood sample collection at baseline for the analysis of single
nucleotide polymorphisms, after randomization on clinical trial IBCSG-35-07 and prior to the
beginning treatment on IBCSG-35-07. Patients also undergo serum collection at baseline and
at 9, 10.5, and 12 months for the analysis of estrogen levels and sex hormone binding
globulins. Patients undergo measurement of grip strength at baseline and at 9 and 12 months.
Samples may be banked for future research studies.

Patients complete quality-of-life questionnaires (Breast Cancer Prevention Trial [BCPT]
Symptom Scales on Form 35-PRS and IBCSG Trial 35-07 QL Form) periodically.