title: Thyroid Function after Postoperative Radiation Therapy in
  Patients with Breast Cancer
abstract: Objective: The aim of this study was to assess thyroid function in breast cancer patients exposed to therapeutic
  external beam radiation. The focus was on possible progressive changes and any relationships between the incidence of
  primary hypothyroidism, the time required to become hypothyroid, and factors such as chemotherapy, hormonotherapy
  and immunotherapy. Materials and Methods: Seventy females undergoing 3D conformal and IMRT radiation therapy
  for breast cancers were enrolled in a non-randomized prospective study. The patients was divided into two groups:
  those after mastectomy or breast conserving surgery (BCS) were irradiated to a scar of the chest wall/breast and the
  ipsilateral supraclavicular and the axillary areas (supraclavicular radiotherapy group - SC-RT group – 32 patients) and
  the control group receiving adjuvant chest wall/breast RT only (BCT group - 38 patients).The total doses were 50.0
  to 70 Gy in 5 to 7 weeks. The median follow-up term was 24 months (range, 1–40 months). Thyroid function was
  evaluated by measuring thyroid stimulating hormone (TSH), free thyroxine (fT4), and free triiodothyronine (fT3) levels.
  The minimum, maximum and mean thyroid gland doses for 20 Gy (V20) were calculated for all patients. Results:
  Statistically significant results were obtained for the SC-RT group. Two yearsa fter the end of RT the chance of an event
  was increased in 6% of the population (p=0.009) in the SC-RT group. In the BCT group no significance was noted. No
  statistically significant differences were found for V20, chemio-, immunotherapy and hormonotherapy or Ki67 values
  (p=0.12). No significant results were obtained for development of hypothyroidism and clinical factors (age, thyroid
  volume, treatment modalities). Conclusion: Radiotherapy is associated with a higher incidence of thyroid toxicity in
  breast cancer patients. Routine thyroid function monitoring should be recommended in such cases.
authors.affiliation: Department of Radiotherapy, Regional Clinical Hospital in Zielona Gora Zyty 26, 65-001 Zielona Gora, Poland |University of Zielona Gora, Faculty of Medicine and Health Sciences, Poland, Email: edyta.wolny@gmail.com.
authors.forename: Edyta
authors.initials: E
authors.lastname: Wolny-Rokicka
authors.forename: Andrzej
authors.initials: A
authors.lastname: Tukiendorf
authors.forename: Jerzy
authors.initials: J
authors.lastname: Wydmański
authors.forename: Danuta
authors.initials: D
authors.lastname: Roszkowska
authors.forename: Bogusław
authors.initials: BS
authors.lastname: Staniul
authors.forename: Agnieszka
authors.initials: A
authors.lastname: Zembroń-Łacny
keywords: Thyroid disorders; external beam radiation; breast cancer; hypothyroidism