Thyroid hormone and breast carcinoma

Abstract

Background It has been a matter of controversy whether there is an increased risk of lung cancer among asbestos‐exposed workers without radiographic asbestosis. A previous study of lung cancer risk among asbestos‐cement workers has been updated with an additional 12 years of follow‐up. Methods Subjects had received radiographic examination at 20 and 25 years from first exposure to asbestos. Radiographs were interpreted by a single National Institute of Safety and Health (NIOSH)‐certified B‐reader using the 1971 International Labor Office (ILO) Classification of the pneumoconioses as reference standard. Asbestosis was defined as an ILO coding of 1/0 or higher. Standardized Mortality Ratios (SMRs) were calculated using the general population of Ontario as reference. Results Among asbestos‐cement workers without radiographic asbestosis at 20 years latency the lung cancer SMR was 3.84 (2.24–6.14). Among workers without asbestosis when examined at 25 years latency the SMR was 3.69 (1.59–7.26). Conclusions Workers from an Ontario asbestos‐cement factory who did not have radiographic asbestosis at 20 or 25 years from first exposure to asbestos continued to have an increased risk of death from lung cancer during an additional 12 years of follow‐up. Am. J. Ind. Med. 53:1065–1069, 2010. © 2010 Wiley‐Liss, Inc.

Thyroid dysfunction and tyrosine kinase inhibitors in renal cell carcinoma

“…Thyroid hormones may be permissive for tumor growth and may reduce survival in recurrent brain tumors (Hercbergs et al 2003) and in head and neck cancer (Nelson et al 2006). Moreover, a relationship between hypothyroidism and reduced incidence and less aggressiveness of breast cancer was demonstrated (Cristofanilli et al 2005). In 2007, Oetting Alexis demonstrated that thyroid hormones play important roles in proliferation and apoptosis (Oetting 2007).…”

Triiodothyronine and breast cancer

“…Postmenopausal BC patients have been reported to have a significant increase in THs, suggesting that an imbalance between estradiol (E2) and T3 fosters the development of BC [44][45][46] . Conversely, hyperthyroidism has been associated with a reduction in the incidence of BC [47] . The literature describes an increase in survival in hyperthyroid patients with BC, suggesting that hyperthyroidism may protect against the development of BC by increasing steroid hormone binding globulin and by reducing estrogen stimulation of the breast tissue [48] .…”

“…A recently conducted meta-analysis found no statistically significant association between TH replacement and BC risk [19] . One of these studies demonstrated primary hyperthyroidism as a strong protective factor against BC after adjusting for clinical parameters including TH replacement therapy [47] . The literature contains a few studies that show a correlation between TH replacement therapy and BC, despite a tendency towards a non-statistical association between the two.…”

“…In addition, other studies reported an increase in survival of BC patients who had high TH levels [48] . Some studies that evaluated thyroid pathology reported that BC rarely occurred in hyperthyroid women [58] , while others reported that primary hyperthyroidism is associated with a reduced incidence of primary BC [47] . TH replacement therapy primarily entails administering doses of levothyroxine sodium ranging from 1.6 to 1.8 μcg/kg per day [59] .…”

“…These postmenopausal women with BC had a significant increase in their thyroid/estradiol ratio, suggesting that an imbalance between E2 and T3 fosters the development of BC [44] . Conversely, hyperthyroidism has been associated with a reduction in the incidence of BC [47] . Many in vitro and in vivo studies have related THs to human cancer since Beatson [57] described the use of thyroid extracts for treating metastatic BC in 1986.…”