PMID- 29580932
OWN - NLM
STAT- MEDLINE
DCOM- 20190529
LR  - 20190529
IS  - 1873-4022 (Electronic)
IS  - 1873-4022 (Linking)
VI  - 44
IP  - 1
DP  - 2019 Spring
TI  - Postradiation hypothyroidism in head and neck cancers: A Department of Veterans 
      Affairs single-institution case-control dosimetry study.
PG  - 56-60
LID - S0958-3947(18)30019-0 [pii]
LID - 10.1016/j.meddos.2018.02.001 [doi]
AB  - We performed a case-control study to characterize the dose-volume relationship 
      and other variables leading to hypothyroidism after head and neck (H&N) cancer 
      radiation therapy (RT) in a homogenous Veterans Affairs (VA) population. All 
      records of patients receiving RT for various H&N cancers at a single VA medical 
      center between 2007 and 2013 (n = 143) were screened for post-RT thyroid 
      stimulating hormone (TSH) levels (n = 77). The thyroid gland was contoured on 
      each slice of the planning computed tomography scan when available (hypothyroid: 
      n = 18; euthyroid > 2 years: n = 16), and dose-volume histograms based on 
      physical dose and biologically equivalent dose (BED) were compared systematically 
      to find the significant dose-volume thresholds that distinguish the patients who 
      developed clinical hypothyroidism. Dosimetric and clinical variables were 
      considered in univariate and multivariate analysis. Preirradiation prevalence of 
      hypothyroidism was 8 of 143 (5.6%). After RT, 36 of 77 (47%) screened patients 
      had abnormally high TSH, of which 22 of 36 (61%) had clinical hypothyroidism 
      after 1.29 +/- 0.99 years. The median follow-up durations were 3.3 years and 4.7 
      years for euthyroid and hypothyroid patients, respectively. Compared with the 
      euthyroid cohort (n = 41), these hypothyroid patients displayed no significant 
      difference in age, gender, primary tumor site, thyroid volume, hypertension, 
      diabetes, or use of chemotherapy, surgery, or intensity-modulated radiation 
      therapy (IMRT). They were more likely to have had stage 3 or 4 cancer than 
      euthyroid patients (86.5% vs 73.2%, p = 0.01). The odds ratios of hypothyroidism 
      for stage 3 + 4 cancers and V50Gy < 75% were 5.0 and 0.2, respectively 
      (p < 0.05). Equivalent BED threshold of V75Gy(3) < 75% gave an odds ratio of 
      0.156 for developing hypothyroidism (p = 0.02). The prevalence of post-RT 
      clinical hypothyroidism was relatively high for patients with H&N cancers and 
      warrants routine surveillance, especially in those with higher stage malignancy. 
      V50Gy < 75% may be a useful guideline to avoid hypothyroidism. We also show BED 
      data which could be used for unconventionally fractionated schemes, and 
      V75Gy(3) < 75% may be a useful guideline.
CI  - Published by Elsevier Inc.
FAU - Lin, Alexander J
AU  - Lin AJ
AD  - Department of Radiation Oncology, VA Long Beach Healthcare System, Long Beach, 
      CA; Department of Radiation Oncology, University of California, Irvine, CA.
FAU - Zhang, Juying
AU  - Zhang J
AD  - Department of Radiation Oncology, VA Long Beach Healthcare System, Long Beach, 
      CA; Department of Radiation Oncology, University of California, Irvine, CA.
FAU - Cho-Lim, Jennie
AU  - Cho-Lim J
AD  - Department of Radiation Oncology, VA Long Beach Healthcare System, Long Beach, 
      CA; Department of Radiation Oncology, University of California, Irvine, CA.
FAU - Inouye, Warren
AU  - Inouye W
AD  - Department of Radiation Oncology, VA Long Beach Healthcare System, Long Beach, 
      CA; Department of Radiation Oncology, University of California, Irvine, CA.
FAU - Lee, Steve P
AU  - Lee SP
AD  - Department of Radiation Oncology, VA Long Beach Healthcare System, Long Beach, 
      CA; Department of Radiation Oncology, University of California, Los Angeles, CA. 
      Electronic address: SPLee@mednet.ucla.edu.
LA  - eng
PT  - Journal Article
DEP - 20180323
PL  - United States
TA  - Med Dosim
JT  - Medical dosimetry : official journal of the American Association of Medical 
      Dosimetrists
JID - 8908862
SB  - IM
MH  - Aged
MH  - Case-Control Studies
MH  - Female
MH  - Head and Neck Neoplasms/*radiotherapy
MH  - Humans
MH  - Hypothyroidism/*etiology
MH  - Male
MH  - Middle Aged
MH  - Radiometry
MH  - Radiotherapy/*adverse effects
MH  - United States
MH  - United States Department of Veterans Affairs
OTO - NOTNLM
OT  - BED
OT  - Biologically effective dose
OT  - Head and neck radiation
OT  - Hypothyroidism
OT  - Late toxicity
EDAT- 2018/03/28 06:00
MHDA- 2019/05/30 06:00
CRDT- 2018/03/28 06:00
PHST- 2017/09/11 00:00 [received]
PHST- 2017/12/06 00:00 [revised]
PHST- 2018/02/06 00:00 [accepted]
PHST- 2018/03/28 06:00 [pubmed]
PHST- 2019/05/30 06:00 [medline]
PHST- 2018/03/28 06:00 [entrez]
AID - S0958-3947(18)30019-0 [pii]
AID - 10.1016/j.meddos.2018.02.001 [doi]
PST - ppublish
SO  - Med Dosim. 2019 Spring;44(1):56-60. doi: 10.1016/j.meddos.2018.02.001. Epub 2018 
      Mar 23.