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Meta-Analysis
. 2023 Apr:68:216-224.
doi: 10.1016/j.breast.2023.02.008. Epub 2023 Feb 18.

Breast cancer, breast cancer-directed radiation therapy and risk of hypothyroidism: A systematic review and meta-analysis

Elisabeth Solmunde  1 , Anne Mette Falstie-Jensen  1 , Ebbe L Lorenzen  2 , Marianne Ewertz  3 , Kristin V Reinertsen  4 , Olaf M Dekkers  5 , Deirdre P Cronin-Fenton  6
Affiliations
Meta-Analysis

Breast cancer, breast cancer-directed radiation therapy and risk of hypothyroidism: A systematic review and meta-analysis

Elisabeth Solmunde et al. Breast. 2023 Apr.

Abstract

Objective: Breast cancer and breast cancer-directed radiation therapy (RT) may increase the risk of late effects, such as hypothyroidism. We conducted a systematic review and meta-analysis to investigate the association between breast cancer, RT, and risk of hypothyroidism in breast cancer survivors.

Methods: Through February 2022, we searched PubMed, EMBASE, and references of relevant articles, to identify papers on breast cancer and breast cancer-directed RT and subsequent risk of hypothyroidism. Articles were screened by title and abstract and reviewed for eligibility. We used a pre-formed data extraction sheet and identified key design elements that could potentially introduce bias. The main outcome was the confounder-adjusted relative risk (RR) of hypothyroidism in breast cancer survivors versus women without breast cancer, and in breast cancer survivors according to the receipt of RT to the supraclavicular lymph nodes. We used a random-effects model to calculate pooled RRs and associated 95% confidence intervals (95% CI).

Results: From 951 papers screened by title and abstract, 34 full-text papers were reviewed for eligibility. We included 20 studies published between 1985 and 2021-19 were cohort studies. Compared with women without breast cancer, the pooled RR of hypothyroidism in breast cancer survivors was 1.48 (95% CI: 1.17, 1.87), with highest risk associated with RT to the supraclavicular region (RR = 1.69, 95% CI: 1.16, 2.46). The most important limitations of the studies were small sample size yielding estimates with low precision, and lack of data on potential confounders.

Conclusion: Breast cancer and radiation therapy to the supraclavicular lymph nodes is associated with an increased risk of hypothyroidism.

Keywords: Breast cancer; Hypothyroidism; Meta-analysis; Radiation therapy; Treatment late effects.

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Conflict of interest statement

Declaration of competing interest The authors declare no conflict of interest.

Figures

Fig. 1
Fig. 1
Study selection process.
Fig. 2a
Fig. 2a
Pooled relative risk and associated 95% CIs for the association between breast cancer and hypothyroidism, ordered according to the magnitude of the relative risk.
Fig. 2b
Fig. 2b
Pooled relative risk and associated 95% CIs for the association between radiation therapy to the supraclavicular lymph nodes and hypothyroidism, ordered according to the magnitude of the relative risk.
See this image and copyright information in PMC

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