Breast joint clinic ( tumor board) May 21 , 2016

Case presentation :  coincidence of breast and thyroid cancer

58 yrs female , history of breast cancer 1392

PMH: right breast cancer 92//7/11 – BCT and axillary dissection

PE: supraclavicular mass

Pathology of BCT and axillary LN: IDC , ER- , PR- , HER2 (2+), Ki67 15% , LN 8/9+

CNB of Rt supraclavicular mass: Positive for malig compatible with Carcinoma

Whole body scan: Hypermetabolic focus in right side of nasopharynx and right lobe of thyroid . right          
                             paratracheal , axillary ,  bilateral hilar and subcarinal adenopathies. Single focus of metabolic
                              activity in right 6th rib.

PET/CT: right paratracheal, hilar, axillary and subcarinal adenopathies. Asymmetric enlargement of right thyroid               lobe with hypermetabolic nodule is seen.

Joint recommendation:   ENT exam, Thyroid biopsy,

 

Discussion:

   Women with a diagnosis of thyroid cancer were reported more likely to develop breast cancer than women without such a diagnosis; this association was first noted in 1966. A study published in 2001 sought to overcome the problem of small sample size that plagued many of the previous studies by using SEER registry data from 1973 to 1994. In this analysis , premenopausal white women who had thyroid carcinoma were more likely to develop breast cancer 5 to 20 days later than women without a diagnosis of thyroid carcinoma(RR=1.41, 95%). No evidence was found of such increase risk among post -menopausal white women.  Point estimates of RR were elevated in both premenopausal and postmenopausal black women, but statistical power was poor because of low numbers. No increased risk was seen of subsequent thyroid cancer following an initial diagnosis of breast cancer, suggesting that a woman’s susceptibility to breast cancer after thyroid cancer may be related to treatment of the thyroid cancer rather than to genetic or environmental susceptibility to these two cancers simultaneously.(1)

Breast cancer survivors are at increased risk of developing thyroid cancer, especially within five years of their breast cancer diagnosis. Recognition of this association between breast and thyroid cancer should prompt vigilant screening for thyroid cancer among breast cancer survivors. Compared with patients with breast cancer alone, women who had breast cancer followed by thyroid cancer were younger on average when diagnosed with their breast cancer. They also were more likely to have had invasive ductal carcinoma, a smaller focus of cancer, and to have received radiation therapy as part of their breast cancer treatment. There was no difference in risk based on whether the breast cancer was hormone receptor positive or had spread to lymph nodes. (2)

Compared with patients who had only thyroid cancer, breast cancer survivors who developed thyroid cancer were more likely to have more aggressive type of thyroid cancer, but the cancers were smaller in size and fewer patients required additional radioactive iodine treatment. According to this study they recommend that every year for the first five years after a breast cancer diagnosis, especially survivors who received radiation therapy should undergo a dedicated thyroid exam.(2)

 Many breast cancers are sensitive to hormons like estrogen, and according to researchers, thyroid hormone has estrogen-like effects at high levels. So, for years, scientists have wondered whether having too much thyroid hormone might promote the development of breast cancer. A new study suggests the answer could be “yes”. (3)

Explanation for these associations include detection bias, shared hormonal risk factors, treatment effect, and genetic susceptibility. (4)  

References:

1-Diseases of the Breast Jay R. Harris

2-The Endocrine Society  March 2015

3-Harvard Health Publications .Apr 2016

4-cancer Epidermiol Biomarders Prev. 2016 Feb;25(2):231-8





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