Primary intrathoracic malignant effusion: a descriptive study.
BACKGROUND
Patients who present with malignant pleural/malignant effusion without a definite primary site are not well described in the medical literature. In the course of our clinical practice, we have observed certain traits that are peculiar to patients with such a presentation. We have applied the term primary intrathoracic malignant effusion (PIME) to describe this condition.


OBJECTIVE
Patients must fulfill the following criteria before a diagnosis of PIME can be made: clinical presentation dominated by pleural/pericardial effusion; histologic proof of malignancy obtained from the pleura and/or pericardium; no definite primary site in the lungs or elsewhere from CT scan of the chest, chest radiograph, or physical and endoscopic examination; no history of malignancy; and no history of asbestos exposure. Exposure 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 who were referred to the Department of Medical Oncology with a diagnosis of pleural/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 metastases. There was a significant association with ETS exposure when compared to a control group comprised of patients with colonic cancer, matched for 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 metastases. Thirty-eight patients (54%) received chemotherapy. All had platinum-based chemotherapy, except for three patients. The median survival for patients 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 remains largely unknown, although exposure to environmental tobacco smoke may play a part. Platinum-based chemotherapy may have a positive biological effect on this disease. More studies are required to elucidate the epidemiology, possible etiologic factors, and treatment options for this group of patients.
Ang
P
P
Department of Medical Oncology, National Cancer Center, Singapore.
Tan
E H
EH
Leong
S S
SS
Koh
L
L
Eng
P
P
Agasthian
T
T
Cheah
F K
FK
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000970:Antineoplastic Agents / Q000627:therapeutic use; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009382:Neoplasms, Unknown Primary; D010490:Pericardial Effusion / Q000175:diagnosis / Q000209:etiology* / Q000401:mortality; D016066:Pleural Effusion, Malignant / Q000175:diagnosis / Q000209:etiology* / Q000401:mortality; D012189:Retrospective Studies; D012907:Smoking; D015996:Survival Rate
D000970:Antineoplastic Agents