Pleural effusions following supervoltage radiation for breast carcinoma.

Abstract

The appearance of a pleural effusion in a patient previously treated for carcinoma of the breast has been almost universally considered to indicate metastatic involvement of the pleura and a serious prognosis, particularly if the neoplasm was originally considered inoperable or showed evidence of recurrence following surgery. In the past, this interpretation was almost invariably correct, whether or not the treatment included radiotherapy to the breast and its adnexal regions. Exceedingly few nonmalignant effusions were noted during the era when 200- to 250-kv therapy was conventionally employed, and the pleura has been considered distinctly radioresistant. In recent years, however, ultrahigh-voltage therapy has permitted considerably larger doses to be delivered to the mediastinal, pleural, and parenchymal regions, as well as to the loci of probable disease. As a result, greater radiation effects on the pleura, lung parenchyma, and mediastinal region have been anticipated and, indeed, already noted in a number of clinics where these higher voltages have been employed. At the Francis Delafield Hospital, 2-million-volt radiotherapy has been directed to the breast, axilla, and supraclavicular and internal mammary regions in the treatment of inoperable breast carcinoma and of certain cases postoperatively. With the employment of this technic, we have observed the development of pleural effusions in a small but significant number of cases in which the course and clinical observations strongly suggested that the fluid did not represent metastases but may well have been the result of irradiation. These patients have remained well for considerable periods of time with their effusions and have shown no other signs of possible metastases. Because super-voltage therapy is assuming an increasing role in the treatment of breast carcinoma, it was thought desirable to report this group of cases. The effects on the lung fields of radiotherapy of regional neoplastic disease have been extensively dealt with in numerous communications since the report by Groover, Christie, and Merritt (1), in 1923, on a series of such cases. Most authors make little or no mention of pleural changes, stressing almost exclusively alterations in the pulmonary parenchyma. Indeed, Engelstad (2, 3), after his thorough investigation of the effects of radiations on the lungs of animals, concludes that the pleura is radioresistant and that pleural changes are seldom encountered in spite of marked parenchymal damage. These findings are in accord with those of Warren and Gates (4, 5), who postulate that the pleura, being composed mainly of inert fibrous tissue, should be the last structure to react.