Multivariate analysis of prognostic features in malignant pleural effusions from breast cancer patients.

To identify prognostic indicators in breast cancer patients with malignant pleural effusions, we analyzed the cytopathologic features of 57 fluids representing the first pathologic diagnosis of a distant metastasis in these women. The specimens were analyzed prior to reviewing the clinical records. The median survival of 55 patients who died of the disease was five months following the effusion diagnosis (range, 1-114). Univariate analysis identified three cytopathologic features that correlated with relatively prolonged survival: arrangement of tumor cells in spheroids, slight nuclear atypia and low mitotic rate. Women whose tumor cells formed spheroids survived a median of 24.5 months as compared to 4 months for women with all other architectural patterns (P = .004). Multivariate analysis revealed that slight nuclear atypia and low mitotic rate strongly correlated with spheroid formation. Since breast cancers that form spheroids in effusions portend a relatively favorable prognosis, we recommend that cytopathologists comment on this pattern when reporting on metastatic breast carcinoma in pleural fluids.