An association between postoperative radiotherapy for primary breast cancer in 11 National Surgical Adjuvant Breast and Bowel Project (NSABP) studies and the subsequent appearance of pleural mesothelioma.
OBJECTIVE
Among the minority of patients with pleural mesothelioma and no known exposure to asbestos, there have been case reports suggesting a possible association with previous radiotherapy. The association between radiotherapy for primary breast cancer and the subsequent occurrence of mesothelioma was investigated in women entered into 11 National Surgical Adjuvant Breast and Bowel Project (NSABP) prospective clinical trials for breast cancer.


METHODS
Follow-up information was obtained on 22,140 patients entered into 11 NSABP clinical trials for treatment of primary breast cancer between 1971 and 1994. Postoperative radiotherapy was administered to 9342 patients, mainly after lumpectomy. Postlumpectomy patients were treated with radiotherapy just to the ipsilateral breast and without regional nodal irradiation. There were 12,798 patients who did not have postoperative radiotherapy, and almost all had mastectomy.


RESULTS
Three pleural mesotheliomas were identified, and all occurred in the ipsilateral thorax of the irradiated patients (P = 0.009). All had received postlumpectomy breast irradiation for ductal carcinoma in situ. None had a known previous exposure to asbestos.


CONCLUSIONS
There appears to be a small but statistically significant increased risk of developing mesothelioma following radiotherapy administered for primary breast cancer. However, in absolute numbers, the risk is too small to be considered a contraindication to administering radiotherapy when indicated.
Deutsch
Melvin
M
UPMC Presbyterian Department of Radiation Oncology, Graduate School of Public Health, University of Pittsburgh, Pittsburgh, PA, USA. deutschm@upmc.edu
Land
Stephanie R
SR
Begovic
Mirsada
M
Cecchini
Reena
R
Wolmark
Norman
N
D000328:Adult; D000368:Aged; D001943:Breast Neoplasms / Q000532:radiotherapy*; D002285:Carcinoma, Intraductal, Noninfiltrating / Q000532:radiotherapy; D005260:Female; D006801:Humans; D008654:Mesothelioma / Q000209:etiology*; D008875:Middle Aged; D010997:Pleural Neoplasms / Q000209:etiology*; D011184:Postoperative Period; D011446:Prospective Studies; D011832:Radiation Injuries / Q000150:complications*; D018714:Radiotherapy, Adjuvant / Q000009:adverse effects