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Cancer mortality after iodine‐131 therapy for hyperthyroidism
Author(s) -
Hall Per,
Berg Gertrud,
Bjelkengren Göran,
Boice John D.,
Ericsson UllaBritt,
Hallquist Arne,
Lidberg Monika,
Lundell GÖRan,
Tennvall Jan,
Wiklund Kerstin,
Holm LarsErik
Publication year - 1992
Publication title -
international journal of cancer
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.475
H-Index - 234
eISSN - 1097-0215
pISSN - 0020-7136
DOI - 10.1002/ijc.2910500611
Subject(s) - medicine , standardized mortality ratio , cancer , thyroid cancer , stomach cancer , breast cancer , leukemia , bladder cancer , confidence interval , epidemiology , gastroenterology , surgery
Cancer mortality was studied in 10,552 Swedish hyperthyroid patients treated with 131 l between 1950 and 1975. The patients were matched with the Swedish Cause‐of‐Death Register and the cases of 977 patients who died from cancer or leukemia were studied. The patients had been followed up for an average of 15 years (range 0 to 35 years), and the overall standardized mortality ratio (SMR) was 1.09 [95% confidence interval (CI) = 1.03 to 1.16], with a higher risk for women. The highest mortality was seen during the first year after exposure (SMR = 1.15) and decreased for the following 9 years (SMR = 1.04). The risk of dying from a cancer in the digestive tract and respiratory organs was significantly elevated more than 10 years after exposure, as was the overall cancer mortality (SMR = 1.14). No increased risk was seen for leukemia, bladder cancer or breast cancer. Younger patients and those receiving 131 I at higher activity had higher SMRs than older patients and those receiving lower activity. Patients with toxic nodular goiter had higher risk than those with Graves' disease. The lack of increasing mortality over time and with increasing activity of 131 I administered argues against a carcinogenic effect of 131 I. However, in the case of cancers of the stomach, the 131 I exposure could have contributed to the excess mortality from these cancers.