Anastrozole and letrozole: an investigation and comparison of quality of life and tolerability.
Previous studies have demonstrated that both anastrozole and letrozole are well tolerated. Letrozole suppresses estrogen to a greater degree than anastrozole in the serum and breast tumor. Concerns have been raised that greater potency may adversely affect patients' quality of life (QOL). One hundred eighty-one postmenopausal women with invasive estrogen receptor-positive breast cancers were randomized to receive either 12 weeks of letrozole followed by 12 weeks of anastrozole or the reverse sequence. One hundred and six received immediate adjuvant aromatase inhibitors (AIs) following surgery, and 75 received extended adjuvant therapy. The Functional Assessment of Cancer Therapy Endocrine Subscale (FACT-B-ES) QOL questionnaires were completed to assess QOL on each drug. Additional side-effect profiles were collected. Each patient completed a patient preference form. Twenty-one patients withdrew before study end, 10/179 (5.6%) while taking letrozole and 4/173 (2.3%) while taking anastrozole (P = 0.12). Tamoxifen-naïve patients had a higher mean ES (endocrine symptoms subscale) score at entry versus those having extended therapy (66.0 vs. 61.9; P = 0.001). There was no significant change in FACT-B-ES (overall) scores or ES scores while patients were taking anastrozole or letrozole and no significant differences between drugs. Nearly 80% of patients reported one or more side effects with either agent. No differences in frequency, grade, or range of side effects were seen between drugs. Of 160 patients, 49 (30.6%) preferred letrozole, 57 (35.6%) preferred anastrozole, and 54 (33.8%) had no preference (P = 0.26, Pearson's Chi-squared test). In conclusion, both AIs are equally well tolerated. There were no significant differences in QOL scores between the two drugs.
Dixon
J Michael
JM
Edinburgh Breast Unit, Western General Hospital, Edinburgh, EH4 2XU, UK. jmd@ed.ac.uk
Renshaw
Lorna
L
Langridge
Carolyn
C
Young
Oliver E
OE
McHugh
Mary
M
Williams
Linda
L
Murray
Juliette
J
Macaskill
E Jane
EJ
McCaig
Fiona
F
Dixon
Oliver M
OM
Fallowfield
Lesley J
LJ
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000077384:Anastrozole; D000970:Antineoplastic Agents / Q000627:therapeutic use*; D018931:Antineoplastic Agents, Hormonal / Q000627:therapeutic use*; D001943:Breast Neoplasms / Q000188:drug therapy*; D018592:Cross-Over Studies; D004703:Endocrine System; D006801:Humans; D000077289:Letrozole; D008875:Middle Aged; D009570:Nitriles / Q000627:therapeutic use*; D011788:Quality of Life; D013629:Tamoxifen / Q000627:therapeutic use*; D016896:Treatment Outcome; D014230:Triazoles / Q000627:therapeutic use*
D000970:Antineoplastic Agents; D018931:Antineoplastic Agents, Hormonal; D009570:Nitriles; D014230:Triazoles; D013629:Tamoxifen; D000077384:Anastrozole; D000077289:Letrozole