Biological characteristics of cancers involving the serosal cavities.

The presence of cancer cells in effusions within the serosal (peritoneal, pleural, and pericardial) cavities is a clinical manifestation of advanced-stage cancer and is associated with poor survival. Tumor cells in effusions most frequently originate from primary carcinomas of the ovary, breast, and lung, and from malignant mesothelioma, a native tumor of this anatomic site. Unlike the majority of solid tumors, particularly at the primary site, cancer cells in effusions are not amenable to surgical removal and failure in their eradication is one of the main causes of treatment failure. In recent years, we have studied the biological characteristics of ovarian carcinoma, breast carcinoma, and malignant mesothelioma cells in effusions and compared it to their counterparts in primary tumors and solid metastases. Our data show that a large number of cancer-associated molecules, including cell adhesion proteins, proteolytic enzymes, growth factor receptors, signaling molecules, and transcription factors, are differentially expressed along tumor progression and have a different prognostic value, depending on the organ sampled. In ovarian carcinoma, several of these molecules are differentially expressed in primary diagnosis (prechemotherapy) and disease recurrence (postchemotherapy) specimens, reflecting the effect of disease progression and chemotherapy, and have different prognostic significance as function of disease progression. The findings presented in this review underscore the need to take into consideration the unique biology of cancer cells in effusions if patient-tailored molecular therapy is to become a successful treatment modality in these malignancies.