Circulating and disseminated tumor cells in ovarian cancer: a systematic review

Objectives: Detecting circulating tumor cells (CTCs) in the peripheral blood and disseminated tumor cells (DTCs) in the bone marrow of cancer patients has proven feasible and of prognostic value in different neoplasms. However, the clinical significance of CTCs and DTCs in ovarian cancer and its association with outcome remains unclear.

Methods: A literature search in PubMed was performed from January 2000 to December 2013 for studies evaluating CTCs and/or DTCs and its association with clinicopathological characteristics and clinical outcome in ovarian cancer. The main outcome measures were progression-free survival (PFS) and overall survival (OS).

Results: Fourteen studies met the inclusion criteria. Median study size was 84 patients (range 43-216). Median follow-up was 19months (range 5-52). Most studies were small case series (n<100; studies; 71%). The majority of studies used an immunophenotyping approach to identify CTCs and/or DTCs, but only 3 studies (21%) used the FDA-approved Cell Search method. Despite the differences in methodology among studies the presence of CTCs and DTCs tended to be associated with higher baseline CA-125 serum levels, higher odds of residual disease after surgery, and worse survival in ovarian cancer across studies. No consistent intra-patient correlation was observed between DTCs detected in the bone marrow and CTCs detected in the blood.

Conclusions: The presence of CTCs and DTCs is associated with adverse clinicopathological characteristics and poor clinical outcomes in ovarian cancer patients. Its implementation as a valuable prognostic tool in the clinical setting requires uniform methodology and prospective validation.