Breast cancer in women after repeated fluoroscopic examinations of the chest
Boice, J.D.; Monson, R.R.
Journal of the National Cancer Institute 59(3): 823-832
1977
ISSN/ISBN: 0027-8874 PMID: 894747 Document Number: 112768
A follow-up study of 1764 female patients, discharged from 2 tuberculosis sanatoria in Massachusetts [USA], between 1930 and 1954, was conducted. In the course of air collapse therapy of the lung (pneumothorax and pneumoperitoneum), 1047 women were fluoroscopically examined an average of 102 times over a period of several years. A comparison group of 717 women with tuberculosis received other treatments that did not require fluorescopic monitoring. A 1975 mailing address or a death certificate was obtained for 93.6% of the study subjects, and 78% of 1146 living patients responded to a mailed questionnaire. An excess of breast cancer (41 observed and 23.3 expected) was seen among the fluoroscopically examined women, whereas no excess (15 observed and 14.1 expected) was apparent among the comparison women. When age was considered, the greatest absolute excess breast cancer risk occurred among exposed women who were first treated between the ages of 15 and 19 yr. Among those women 30 yr of age and older at the time of 1st exposure, no elevated breast cancer risk was detected. The failure to observe an excess may be a matter of sampling variation inasmuch as a 50% increased risk could not be excluded. The concentration of excess breast cancer cases among women initially exposed before the age of 30 yr suggests that young women may be particularly sensitive to radiation injury. Breast cancer excess risk was also seen to increase with increasing radiation dose, and a linear dose-response relationship is consistent with the data. The excess breast cancer risk did not appear until 15 yr after initial exposure and was present at the end of 40 yr of observation. The radiation risk estimate for the women living 10 yr or more after 1st exposure is 6.2 excess breast cancer cases per million woman-year-rad.