- Title
- Participant-reported symptoms and their effect on long-term adherence in the International Breast Cancer Intervention Study I (IBIS-I)
- Creator
- Smith, Samuel George; Sestak, Ivanka; Howell, Anthony; Forbes, John; Cuzick, Jack
- Relation
- NHMRC.401200 http://purl.org/au-research/grants/nhmrc/401200
- Relation
- Journal of Clinical Oncology Vol. 35, Issue 23, p. 2666-2673
- Publisher Link
- http://dx.doi.org/10.1200/JCO.2016.71.7439
- Publisher
- American Society of Clinical Oncology
- Resource Type
- journal article
- Date
- 2017
- Description
- Purpose: To assess the role of participant-reported symptoms on long-term adherence to preventive therapy in the United Kingdom sample of the International Breast Cancer Intervention Study (IBIS-I). IBIS-I was a randomized controlled trial that investigated the effectiveness of tamoxifen in reducing the risk of breast cancer among women at increased risk of the disease. Participants and Methods: Women were randomly assigned to tamoxifen versus placebo (20 mg/day; n = 4,279). After 456 exclusions, 3,823 women were included in this analysis. Adherence (< 4.5 years or ≥ 4.5 years) was calculated using data from six monthly clinical visits. Analyses were adjusted for age, Tyrer-Cuzick risk, smoking, use of hormone replacement therapy, menopausal status, baseline menopausal symptoms, and treatment. Results: Overall, 69.7% of women were adherent for at least 4.5 years (tamoxifen: 65.2% v placebo: 74.0%; P < .001). Differences in adherence between treatment arms were observed from 12 months onward (all P < .01) and were largest at 54 months. Dropout rates were highest in the first 12 to 18 months and decreased thereafter. Women reporting nausea/vomiting were less likely to be adherent in both the tamoxifen (odds ratio [OR], 0.57; 95% CI, 0.37 to 0.86; P = .007) and placebo (OR, 0.58; 95% CI, 0.37 to 0.93; P = .023) arms. Headaches were associated with adherence only in the placebo arm (OR, 0.62; 95% CI, 0.42 to 0.91; P = .016), whereas gynecologic symptoms were significant only in the tamoxifen arm (OR, 0.77; 95% CI, 0.62 to 0.97; P = .024). Effect sizes for each symptom on adherence were not significantly different between the treatment groups (P > .05). In both treatment arms, we observed significant trends for lower adherence with increasing severity for all symptoms (P < .01) except headaches (P = .054). Conclusion: In the IBIS-I trial, experiencing predefined symptoms in the first 6 months reduced long-term adherence. Effects were similar between treatment arms, suggesting that women were attributing age-related symptoms to preventive therapy. Interventions were required to support symptom management.
- Subject
- International Breast Cancer Intervention Study I (IBIS I); United Kingdom; breast cancer; tamoxifen
- Identifier
- http://hdl.handle.net/1959.13/1344884
- Identifier
- uon:29519
- Identifier
- ISSN:0732-183X
- Rights
- Licensed under the Creative Commons Attribution 4.0 License: http://creativecommons.org/licenses/cc-by/4.0/
- Language
- eng
- Full Text
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