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
Study objectives: 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