Radioactive iodine therapy and breast cancer. A follow-up study of hyperthyroid women
A follow-up study of 1762 hyperthyroid women who were treated at the Massachusetts General Hospital Thyroid Unit between 1946 and 1964 was conducted. The average length of follow-up was 17.2 years. A 1978 mailing address or a death certificate was located for 92% of the women, and 88% of 1058 living patients responded to a mail questionnaire. The standardized mortality ratio (SMR) for all causes of death was 1.3 (95% confidence interval (CI) 1.2-1.4). The standardized mortality ratios for all malignant neoplasms and for breast cancer were 0.9 (95% CI 0.7-1.1) and 1.3 (95% CI 0.8-1.9), respectively. More deaths than expected were observed from endocrine and metabolic diseases (SMR = 1.8, 95% CI 1.2-2.7), circulatory system diseases (SMR = 1.4, 95% CI 1.3-1.6), and respiratory system diseases (SMR = 1.9, 95% CI 1.3-2.6). The standardized incidence ratios (SIR) for all malignant neoplasms and for breast cancer were 0.9 (95% CI 0.8-1.1) and 1.2 (95% CI 0.9-1.5), respectively. A nonsignificant excess breast cancer risk was observed 10 years after the onset of thyroid symptoms and was present at the end of 30 years of observation. A statistically significant excess number of pancreatic cancer cases (SIR = 2.0, 95% CI 1.0-3.7) and a nonsignificant excess of brain cancer cases (SIR = 2.3, 95% CI 0.7-5.3) were observed. Eighty per cent of the women were treated with radioactive iodine. When age at treatment and year of treatment were controlled, women who were ever treated with radioactive iodine had a standardized rate ratio for breast cancer of 1.9 (95% CI 0.9-4.1), compared with those who were never treated with radioactive iodine. Women who developed hypothyroidism as a result of their treatment for hyperthyroidism did not have an increased risk of developing breast cancer (SIR = 1.1, 95% CI 0.8-1.6).
- Research Organization:
- Harvard School of Public Health, Boston, MA (USA)
- OSTI ID:
- 7025160
- Journal Information:
- Am. J. Epidemiol.; (United States), Vol. 127:5
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
HYPERTHYROIDISM
RADIOTHERAPY
MAMMARY GLANDS
NEOPLASMS
RADIOINDUCTION
SIDE EFFECTS
DELAYED RADIATION EFFECTS
IODINE 131
POST-IRRADIATION EXAMINATION
SURVIVAL TIME
BETA DECAY RADIOISOTOPES
BETA-MINUS DECAY RADIOISOTOPES
BIOLOGICAL EFFECTS
BIOLOGICAL RADIATION EFFECTS
BODY
DAYS LIVING RADIOISOTOPES
DISEASES
ENDOCRINE DISEASES
GLANDS
INTERMEDIATE MASS NUCLEI
IODINE ISOTOPES
ISOTOPES
MEDICINE
NUCLEAR MEDICINE
NUCLEI
ODD-EVEN NUCLEI
ORGANS
RADIATION EFFECTS
RADIOISOTOPES
RADIOLOGY
THERAPY
560151* - Radiation Effects on Animals- Man