Breast Cancer Mortality Risk in Women With a History of Thyroid Cancer
Posted: Wednesday, December 11, 2019
A history of thyroid cancer appears to confer a strong protective effect on breast cancer–specific patient survival, according to a study published in PLOS One. This association seems to be particularly striking in patients younger than age 50 who have breast cancer followed by thyroid cancer; these women have a significantly lower mortality than women with breast cancer alone.
“Breast cancer in these patients may represent a special disease entity that is clinically and biologically unique,” stated Weiwei Cheng, PhD, of Johns Hopkins University School of Medicine, Baltimore, and colleagues. “The results have potentially important clinical and biological implications for breast cancer in this special patient population.”
The researchers performed a population-based analysis of 427,893 patients with breast cancer who were identified in the Surveillance, Epidemiology, and End Results 9 registry database (1973–2013). They found 2,569 patients with a history of both breast and thyroid cancers: 1,200 women with breast cancer and a subsequent diagnosis of thyroid cancer and 1,369 women with thyroid cancer and a subsequent diagnosis of breast cancer.
Less-aggressive breast cancer tumor behaviors were observed in patients with a history of breast and thyroid cancers compared with those who have a history of breast cancer alone; the distant metastasis rate was 3.3% versus 7.0%, respectively (P < .001). In patients with breast cancer followed by thyroid cancer and thyroid cancer followed by breast cancer compared with patients with breast cancer alone, breast cancer–specific mortality rates were 9.9% versus 26.4% and 12.4% versus 16.9%, respectively (all P < .001).
Additionally, estrogen/progesterone receptor expression in breast cancer tumors was significantly higher in patients with breast and thyroid cancers than in a matched group of patients with breast cancer alone, evidence that this disease entity may be determined by an intrinsic biologic background.
Disclosure: The study authors reported no conflicts of interest.
