Primary Intrathoracic Malignant Effusion

Patients who present with malignantpleural/malignant effusion without a definite primary site are not welldescribed in the medical literature. In the course of our clinicalpractice, we have observed certain traits that are peculiar to patientswith such a presentation. We have applied the term primaryintrathoracic malignant effusion (PIME) to describe thiscondition. Patients must fulfill thefollowing criteria before a diagnosis of PIME can be made: clinicalpresentation dominated by pleural/pericardial effusion; histologicproof of malignancy obtained from the pleura and/or pericardium; nodefinite primary site in the lungs or elsewhere from CT scan of thechest, chest radiograph, or physical and endoscopic examination; nohistory of malignancy; and no history of asbestos exposure. Exposure toenvironmental tobacco smoke (ETS) among the nonsmokers was examined ina case-control setting. We conducted aretrospective search of our database of patients who were referred tothe Department of Medical Oncology with a diagnosis ofpleural/pericardial effusion from January 1993 to January 2000. Seventy-one of 200 patients from our database metthe criteria. A significant majority of the patients were women (65%)and nonsmokers (72%). All patients had adenocarcinoma shown on biopsy. The majority of patients (63%) had disease localized to theintrathoracic serosal surfaces; the rest had distant metastasesinvolving the lung (50%), bone (27%), liver (19%), brain (8%), andskin (4%). Six patients had two or more sites of distant metastases. There was a significant association with ETS exposure when compared toa control group comprised of patients with colonic cancer, matched forsex and age. The median survival was 10 months for patients withdisease localized to the pleura/pericardium and 7 months for those withdistant metastases. Thirty-eight patients (54%) received chemotherapy. All had platinum-based chemotherapy, except for three patients. Themedian survival for patients treated or not treated with chemotherapywas 12 months and 5 months, respectively. This difference in survivalwas statistically significant (p = 0.003). PIME should be viewed as a distinct entity. Its etiology remains largely unknown, although exposure toenvironmental tobacco smoke may play a part. Platinum-basedchemotherapy may have a positive biological effect on this disease. More studies are required to elucidate the epidemiology, possibleetiologic factors, and treatment options for this group ofpatients.