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.
KeywordsAnastrozole Breast cancer Letrozole Quality of life Tamoxifen
Financial support for medical editorial assistance was provided by Novartis Pharmaceuticals. We thank Maria Soushko, PhD, of Phase Five Communications Inc. for medical editorial assistance with this manuscript. Financial support for this study was provided by Novartis Oncology.
- 1.Cazzaniga ME, Mustacchi G, Pronzato P, De Matteis A, Di Costanzo F, Floriani I, on behalf of the NORA Study Group (2007) Adjuvant treatment of early breast cancer: do the St. Gallen recommendations influence clinical practice? Results from the NORA study. Ann Oncol 18:1976–1980CrossRefPubMedGoogle Scholar
- 4.Forbes JF, Cuzick J, Buzdar A, Howell A, Tobias JS, Baum M, Arimidex, Tamoxifen Alone or in Combination (ATAC) Trialists’ Group (2008) Effect of anastrozole and tamoxifen as adjuvant treatment for early-stage breast cancer: 100-month analysis of the ATAC trial. Lancet Oncol 9:45–53CrossRefPubMedGoogle Scholar
- 6.Buzdar A, Howell A, Cuzick J, the Arimidex, Tamoxifen, Alone or in Combination Trialists’ Group et al (2006) Comprehensive side-effect profile of anastrozole and tamoxifen as adjuvant treatment for early-stage breast cancer: long-term safety analysis of the ATAC trial. Lancet Oncol 7:633–643CrossRefPubMedGoogle Scholar
- 12.Jones SE, Seynaeve C, Hasenburg A et al (2009) Results of the first planned analysis of the TEAM (tamoxifen exemestane adjuvant multinational) prospective randomized phase III trial in hormone sensitive postmenopausal early breast cancer. Cancer Res 69(2 suppl):67s (Abstract 15)Google Scholar
- 18.Cella D, Fallowfield L, Barker P, Cuzick J, Locker G, Howell A, ATAC Trialists Group (2006) Quality of life of postmenopausal women in the ATAC (“Arimidex”, tamoxifen, alone or in combination) trial after completion of 5 years’ adjuvant treatment for early breast cancer. Breast Cancer Res Treat 100:273–284CrossRefPubMedGoogle Scholar
- 19.Ohsumi S, Shimozuma K, Ohashi Y, Nomura Y, Aihara T, Takatsuka Y (2009) Health-related quality-of-life and psychological distress of postmenopausal breast cancer patients after surgery during the randomized trial, N-SAS BC 03, comparing further tamoxifen with switching to anastrozole after adjuvant tamoxifen for 1 to 4 years: the final results. Cancer Res 69(2 suppl):145s–146s (Abstract 1136)CrossRefGoogle Scholar
- 21.Abetz L, Barghout V, Thomas S, Arbuckle R (2005) Letrozole did not worsen quality of life relative to placebo in post-menopausal women with early breast cancer: results from the US subjects of the MA-17 study. Breast Cancer Res Treat 94(suppl 1):A100 Abstract 2047Google Scholar
- 23.Takei H, Ohsumi S, Shimozuma K et al (2006) Health-related quality of life and psychological distress of breast cancer patients after surgery during phase III randomized trial comparing tamoxifen, exemestane, and anastrozole: N-SAS BC 04. Breast Cancer Res Treat 100(suppl 1):S189 Abstract A4054Google Scholar
- 24.Coombes RC, Kilburn LS, Snowdon CF, Intergroup Exemestane Study et al (2007) Survival and safety of exemestane versus tamoxifen after 2–3 years’ tamoxifen treatment (Intergroup Exemestane Study): a randomised controlled trial. Lancet 369:559–570 Erratum in: (2007) Lancet 369:906CrossRefPubMedGoogle Scholar
- 27.Thomas R, Godward S, Makris A, Bloomfield D, Moody AM, Williams M (2004) Giving patients a choice improves quality of life: a multi-centre, investigator-blind, randomised, crossover study comparing letrozole with anastrozole. Clin Oncol (R Coll Radiol) 16:485–491Google Scholar