Thyroid function in women after multimodal treatment for breast cancer stage II/III: comparison with controls from a population sample.
OBJECTIVE
A possible association between thyroid diseases (TD) and breast cancer (BC) has been debated. We examined prevalence and development of TD in women after multimodal treatment for Stage II/III BC compared with women from a general population. Secondarily, we explored the impact of two different radiotherapy (RT) techniques (standardized field arrangements vs. computed tomography [CT]-based dose planning) on TD in BC patients examined 35-120 months after primary BC treatment.


METHODS
A total of 403 BC patients completed a questionnaire about TD and had blood samples taken for analyses of thyroid function. All had undergone postoperative RT with or without (2%) adjuvant systemic treatment. The results in the BC patients were compared with a cancer-free, age-matched control group from a general population (CGr).


RESULTS
There was higher prevalence of self-reported hypothyroidism in the BC patients as compared with the CGr (18% vs. 6%, p < 0.001). The raised prevalence was predominantly due to a substantial increase in the development of hypothyroidism after BC diagnosis, whereas the prevalence of hypothyroidism before BC diagnosis was similar to that observed in the CGr. Patients treated with CT-based RT showed a trend for increased post-BC development of hypothyroidism as compared with those treated with standardized field arrangements (p = 0.08).


CONCLUSIONS
Hypothyroidism is significantly increased in women after multimodal treatment for Stage II/III BC. Radiation to the thyroid gland may be a contributing factor. BC patients should be routinely screened for hypothyroidism.
Reinertsen
Kristin Valborg
KV
Department of Clinical Cancer Research, The Norwegian Radium Hospital, Rikshospitalet University Hospital, Oslo, Norway. kvr@radiumhospitalet.no
Cvancarova
Milada
M
Wist
Erik
E
Bjøro
Trine
T
Dahl
Alv A
AA
Danielsen
Turi
T
Fosså
Sophie D
SD
D000328:Adult; D000368:Aged; D000704:Analysis of Variance; D000971:Antineoplastic Combined Chemotherapy Protocols / Q000627:therapeutic use; D001943:Breast Neoplasms / Q000188:drug therapy / Q000473:pathology / Q000503:physiopathology / Q000532:radiotherapy* / Q000601:surgery; D016022:Case-Control Studies; D003131:Combined Modality Therapy / Q000379:methods; D005260:Female; D006801:Humans; D007037:Hypothyroidism / Q000453:epidemiology* / Q000209:etiology; D008875:Middle Aged; D009367:Neoplasm Staging; D015995:Prevalence; D011880:Radiotherapy Planning, Computer-Assisted; D011795:Surveys and Questionnaires; D017741:Survivors; D013961:Thyroid Gland / Q000528:radiation effects; D014057:Tomography, X-Ray Computed