Circulating tumor cells in the bone marrow of patients with metastatic renal cell carcinoma may be prognostic of outcome

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May 8 2006

Circulating tumor cells in the blood and bone marrow have been examined in a variety of malignancies, including colorectal, breast, and head & neck cancers, to determine their prognostic significance.

The cells are detected through cytokeratin (CK) antibody immunohistochemical staining.

In a previous study, 256 patients with renal cell carcinoma (RCC) without evidence of distant metastases were examined for CK+ cells in bone marrow aspirates and no significant correlation with prognosis was found. In this study by Buchner and colleagues, the prognostic significance of CK+ tumor cells in the bone marrow aspirates of 55 patients with metastatic RCC was examined.

Over a 9 year period, bone marrow aspirates from 55 patients were harvested prior to cytoreductive nephrectomy, and then patients went on to receive systemic cytokine therapy with interleukin 2 and interferon. Disease specific survival was then correlated with a quantitative analysis of CK+ tumor cells in the bone marrow. This population was also compared to the 256 patients without metastatic disease. CK+ cells were found in 42% of patients with metastatic RCC which was significantly higher than patients without metastatic disease (p<0.01). The range of CK+ cells in the bone marrow was 1-7 cells. In their multivariate analysis, while the mere presence of CK+ cells in the bone marrow was not prognostic in patients with metastatic disease (p=0.193), patients with ¡Ý 3 CK+ cells had a significantly worse prognosis, with a median survival of 3.3 months (p< 0.001) (Hazard ratio 10.4).

The presence of circulating tumor cells in the blood and bone marrow appears to be associated with more advanced disease, although it is interesting that their presence does not always correlate with outcome. In this study, quantitative assessment of these cells demonstrated a significant association with outcome that could be used to target patients for more aggressive therapeutic approaches.

Reference:

Cancer 106(7); 1514-1520, 2006.