The Breast-Thyroid Cancer Link: A Systematic Review and Meta-analysis

Abstract

Rates of thyroid cancer in women with a history of breast cancer are higher than expected. Similarly, rates of breast cancer in those with a history of thyroid cancer are increased. Explanations for these associations include detection bias, shared hormonal risk factors, treatment effect, and genetic susceptibility. With increasing numbers of breast and thyroid cancer survivors, clinicians should be particularly cognizant of this association. Here, we perform a systematic review and meta-analysis of the literature utilizing PubMed and Scopus search engines to identify all publications studying the incidence of breast cancer as a secondary malignancy following a diagnosis of thyroid cancer or thyroid cancer following a diagnosis of breast cancer. This demonstrated an increased risk of thyroid cancer as a secondary malignancy following breast cancer [OR = 1.55; 95% confidence interval (CI), 1.44-1.67] and an increased risk of breast cancer as a secondary malignancy following thyroid cancer (OR = 1.18; 95% CI, 1.09-1.26). There is a clear increase in the odds of developing either thyroid or breast cancer as a secondary malignancy after diagnosis with the other. Here, we review this association and current hypothesis as to the cause of this correlation.

Figure 1

Summary of systematic review performed querying both Scopus and PubMed databases

Figure 2

Odds ratio of developing thyroid cancer as a secondary malignancy following diagnosis and treatment for breast cancer. Odds ratio on meta-analysis is 1.55 (95% CI [1.44,1.67])

Figure 3

Odds ratio of developing breast cancer as a secondary malignancy following diagnosis and treatment for thyroid cancer. Odds ratio on meta-analysis is 1.18 (95% CI [1.09,1.26])