Primary intrathoracic malignant effusion - A descriptive study

Background: Patients who present with malignant pleural/malignant effusion without a definite primary site are not wed described in the medical litera ture. In the course of our clinical practice, we have observed certain trai ts that are peculiar to patients with such a presentation. We have applied the term primary intrathoracic malignant effusion (PIME) to describe this c ondition. Study objectives: Patients must fulfill the following criteria before a dia gnosis of PIME can be made: clinical presentation dominated by pleural/peri cardial effusion; histologic proof of malignancy obtained from the pleura a nd/or pericardium; no definite primary site in the lungs or elsewhere from CT scan of the chest, chest radiograph, or physical and endoscopic examinat ion; no history of malignancy; and no history of asbestos exposure. Exposur e to environmental tobacco smoke (ETS) among the nonsmokers was examined in a case-control setting, Methods: We conducted a retrospective search of our database of patients wh o were referred to the Department of Medical Oncology with a diagnosis of p leural/pericardial effusion from January 1993 to January 2000, Results: Seventy-one of 200 patients from our database met the 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 the intrathoracic serosal surfaces; the rest had distant metastases involving the lung (50%), bone (27%), liver (19%), brain (8%), and skin (4%), Six patients had two or more sites of distant me tastases. There was a significant association with ETS exposure when compar ed to a control group comprised of patients with colonic cancer, matched fo r sex and age. The median survival was 10 months for patients with disease localized to the pleura/pericardium and 7 months for those with distant met astases. Thirty-eight patients (54%) received chemotherapy, All had platinu m-based chemotherapy, except for three patients, The median survival for pa tients treated or not treated with chemotherapy was 12 months and 5 months, respectively. This difference in survival was statistically significant (p = 0.003), Conclusions: PIME should be viewed as a distinct entity. Its etiology remai ns largely unknown, although exposure to environmental tobacco smoke may pl ay a part. Platinum-based chemotherapy may have a positive biological effec t on this disease. More studies are required to elucidate the epidemiology, possible etiologic factors, and treatment options for this group of patien ts.