It is no secret that breast cancer is dependent on hormones. There are studies that show that thyroid disorders are common in patients with this type of cancer as well as conflicting reports of their connection in literature. Although it has been linked to hyperthyroidism, hypothyroidism, thyroiditis, and nontoxic goiter in the past, no existing evidence has been made over the role of thyroid function in breast carcinoma. However, recent studies show that there is much more going on between the cancer of the breast and thyroid function indeed.
A Possible Connection
The differences in dietary iodine have been known to cause the geographical variations in the incidence of breast and a relationship between cancer of the breast and iodine has been hypothesized by several authors. The probable interconnection between the thyroid gland and breast tissue are based on the ability of the mammary and thyroid gland to concentrate iodine by a membrane transport mechanism. It has also been hypothesized that thyroid antibodies exert an effect on the breast as well as the thyroid, hence, the incidence of these two occurring together.
Another study observed the high incidence of autoimmune hypothyroidism in cases of patients with cancer of the breasts, as confirmed by antibody positivity in patients and a relationship between the two has been reported. The patients were also found to have higher levels of thyroid antibodies. Using specific assays for thyroid peroxidase and thyroglobulin antibodies, patients were observed to have higher levels of thyroid peroxidase antibodies.
It has also been hypothesized that thyroid function may have a hand in the progression of this particular type of cancer. The main observation of this postulation is that patients with higher levels of thyroid peroxidase were most likely to recover from the cancer. Furthermore, it was hypothesized that the immunologic responses of the patient might be directed at both the breast tumor and the thyroid gland or that both the tumor and thyroid gland express the same properties such that the immune response against the tumor will have an effect on the thyroid gland as well. However, there is no consistency on the significance of thyroid peroxidase activity on cancer and a clear agreement between the two has not yet been reached.
There have also been studies of the prevalence of breast carcinoma in patients with chronic thyroiditis. In another study conducted by Ito Maruchi, patients with Hashimoto’s thyroiditis had an increased risk of developing the particular cancer than other people without Hashimoto’s thyroiditis.
Patients were found to have higher levels of thyroid peroxidase antibodies, although their thyroglobulin antibodies were hardly abnormal. Nodular goiter is also a common occurrence in patients with cancer of the breasts. Abnormal thyroid gland characteristics were also observed in the patients.
However, a definite agreement between thyroid disorders and breast cancers is yet to be reached. Yet knowing the statistics and the odds, it would be well for patients with thyroid disorders to be more observant of breast changes. Self breast examinations or SBE and regular checkups are still commendable for women aged 40 and above and even younger for women with a history of cancer, especially of the breast, up in the family tree.