Early increase in tamoxifen dose in CYP2D6 poor metaboliser breast cancer patients and survival: A propensity score matching analysis

 

by Isabel Blancas, Marina Linares-Rodríguez, Eduardo Martínez de Dueñas, Carmen Herrero-Vicent, María D. Molero-Mir, José M. Garrido, Fernando Rodríguez-Serrano 

 

The Breast: Published: March 23, 2023

 

Purpose

Tamoxifen is a drug used for hormone receptor-positive breast cancers, primarily metabolised by the CYP2D6 enzyme into active metabolites such as endoxifen. CYP2D6 displays varying degrees of activity depending on its genotype. This study aims to analyse the effect of an early increase in tamoxifen dose in poor metabolisers (PM) on survival.

Methods

We enrolled 220 patients diagnosed with breast cancer who were treated with tamoxifen. CYP2D6 polymorphisms were determined, and the phenotype was estimated according to the Clinical Pharmacogenetics Implementation Consortium. Disease-free survival (DFS) and overall survival (OS) were analysed considering the entire patient group, and a subgroup of 110 patients selected by Propensity Score Matching (PSM). All women were treated with 20 mg/day of tamoxifen for 5 years, except PM, who initially received 20 mg/day for 4 months, followed by 40 mg/day for 4 months and 60 mg/day for 4 months before returning to the standard dose of 20 mg/day until completing 5 years of treatment.

Results

The analysis of the influence of CYP2D6 polymorphisms in the complete group and in the PSM subgroup revealed no significant differences for DFS or OS. Furthermore, DFS and OS were analysed in relation to various covariates such as age, histological grade, nodal status, tumour size, HER-2, Ki-67, chemotherapy, and radiotherapy. Only age, histological grade, nodal status, and chemotherapy treatment demonstrated statistical significance.

Conclusion

An early increase in tamoxifen dose in PM patients is not associated with survival differences among CYP2D6 phenotypes.

 

 

 

Breast Surgery Bulletin: Feb 2023

 

Factors associated with weight gain after breast cancer: Results from a community-based survey of Australian women

 

by Carolyn Ee, Adele Cave, Vaishnavi Vaddiparthi, Dhevaksha Naidoo, John Boyages 

 

The Breast: Published: January 25, 2023

 

Purpose

Weight gain after breast cancer is common. The aim of this study was to determine factors associated with weight gain after breast cancer in Australian women.

Methods

A cross-sectional online survey was conducted between November 2017 and January 2018. Women living in Australia who self-identified as having breast cancer or ductal carcinoma in-situ were eligible. We created stepwise linear and logistic regression models to evaluate predictors for absolute and clinically significant (≥5%) weight gain respectively.

Results

Data from 276 women were analysed. Most were Caucasian and 92% had been diagnosed with Stage 0-III breast cancer. Absolute weight gain was associated with hot flushes, being in the menopausal transition at diagnosis, being less physically active than at diagnosis, lower eating self-efficacy when watching television or using a computer, and higher self-efficacy when anxious or nervous (F-ratio = 3.26, R2-adjusted = 0.16, p < .001). Clinically significant weight gain was associated with tamoxifen use (OR 2.7), being less physically active than at diagnosis (OR 3.1), and lower eating self-efficacy when watching television or using a computer (OR 0.82) (Chi-square 64.94, df = 16, p < .001). Weight gain was not associated with chemotherapy, radiotherapy, aromatase inhibitor use, number of lymph nodes removed, or body mass index at diagnosis.

Conclusions

Interventions to prevent weight gain after breast cancer, particularly aiming to maintain physical activity, should be targeted at women receiving tamoxifen. The role of eating self-efficacy, especially attentive eating, in managing weight after breast cancer should be explored.

 

The impact of medication side effects on adherence and persistence to hormone therapy in breast cancer survivors: A quantitative systematic review

 

by Leanne Fleming, Sommer Agnew, Nicola Peddie, Megan Crawford, Diane Dixon, Iain MacPherson 

 

The Breast: VOLUME 64, P63-84, AUGUST 01, 2022 (Published: May 13, 2022)

 

 Background

Hormone Therapy (HT) is recommended for most women with HR-positive primary breast cancer. When taken as intended, HT reduces breast cancer recurrence by 40% and mortality by one-third. The recommended duration of treatment ranges from 5 to 10 years depending on risk of recurrence and the specific HT regimen. However, recent data indicates that rates of HT non-adherence are high and research suggests this may be due to the impact of HT side effects. The contribution of side effects to non-adherence and non-persistence behaviours has rarely been systematically explored, thereby hindering the implementation of targeted intervention strategies. Our aim is to identify, evaluate and summarise the relationship between HT side effects and patterns of adherence and persistence.

Methods

Electronic searches were conducted from inception and were completed by September 2021, utilising Cochrane CENTRAL, Medline, Embase, Web of Science and PsycINFO databases. Searches included a combination of terms related to breast cancer, adherence, hormone therapy and side effects.

Results

Sixty-two eligible papers were identified and study quality varied by study type. Most observational and cross-sectional studies were rated good quality, whereas most controlled intervention studies were rated fair quality. Three studies were rated poor quality. The most frequently measured side effects were pain, low mood, hot flashes, insomnia, anxiety, fatigue, weight gain, concentration/memory problems.

Conclusions

This review identified a lack of consistency in the measurement of adherence and the definition of persistence across studies. The instruments used to measure side effects also varied significantly. This variation and lack of consistency makes it difficult to evaluate and summarise the role of HT side effects in HT adherence and persistence behaviour.