In vitro detection of occult bone marrow metastases in patients with colorectal cancer hepatic metastases

Molecular biomarkers for the detection of metastatic colorectal cancer cells

Approximately half of all patients with colorectal cancer develop local recurrence or distant metastasis during the course of their illness. Recently, the molecular detection of metastatic cancer cells in various types of clinical samples, such as lymph nodes, bone marrow, peripheral blood, and peritoneal lavage fluid, has been investigated as a potential prognostic marker. The prognostic value of molecular tumor cell detection was independent of the type of detection method used. As assays become more sensitive and quantitative, a more thorough assessment of the cancer status of patients will be based on molecular markers alone. At present, it is difficult to conclude that one specific molecular marker is superior to others. Comparative analyses are recommended to assess the prognostic impact of molecular analyses in the same patient and determine the biomarkers that provide the most accurate prognostic information.

Disseminated tumour cells in bone marrow in experimental colon cancer: metastatic or resident?

AIM

There are conflicting data on the biological and prognostic significance of disseminated tumour cells (DTCs) in the bone marrow of colorectal cancer patients since bone metastasis is rare in this disease. The study aimed to determine the origin of bone marrow DTCs using human colorectal cancer cells in in vivo and in vitro experimental settings.

METHOD

CD1 nude female mice were xenotransplanted with SW620 cells (a colorectal cancer cell line isolated from a male patient) injected in the colon wall. At autopsy, the presence of SW620 in the bone marrow (BM), colon and other organs/tissues was recognized by detection of the epithelial marker cytokeratin-19 (CK19) and Y chromosome. In addition SW620 cells or their conditioned medium were cultured with human BM cells.

RESULTS

Macroscopically evident CK19+/Y-chromosome-positive tumours developed only in five mice receiving SW620 cells while putative DTCs (CK19+) were found in the bone marrow of all treated mice. Most of these CK19+ cells were Y chromosome negative, only few being Y chromosome positive. In vitro SW620 cells or their conditioned medium induced CK19 expression in cultured human bone marrow cells.

CONCLUSION

Experimental colorectal cancer can induce the appearance of two distinct CK19+ cell populations in the bone marrow, one of metastatic origin and the other of murine origin. These findings suggest that bone marrow cells may undergo phenotypic modifications induced by cancer cells.

Biology and significance of circulating and disseminated tumour cells in colorectal cancer

PURPOSE

More than 130 years ago, circulating tumour cells (CTCs) and disseminated tumour cells (DTCs) have been linked to metastasis. Since then, a myriad of studies attempted to characterise and elucidate the clinical impact of CTCs/DTCs, amongst others in colorectal cancer (CRC). Due to a flood of heterogeneous findings regarding CTCs/DTCs in CRC, this review aims to describe the known facts about CTC/DTC biology and clinical impact.

METHODS

To identify the basic scientific literature regarding the biology and clinical impact of CTCs/DTCs in CRC, we reviewed the literature in the PubMed database. We focused on publications written in English and published until January 2012. As search terms, we used "colorectal cancer (CRC)", "colon cancer (CC)", "CTC", "DTC", "bone marrow (BM)", "lymph node (LN)", "peripheral blood (PB)", "significance" and "prognosis".

RESULTS

CTC detection and quantification under standardised conditions is feasible. Several studies in large patient settings have revealed prognostic impact of CTCs in CRC. CRC-derived DTC detection and analysis in BM exhibits a more heterogeneous picture but also shows clinical value. Furthermore, the presence of DTCs in LN has a strong prognostic impact in CRC.

CONCLUSIONS

Clinical relevance and prognostic significance of CTCs/DTCs in CRC have been clearly demonstrated in many experimental studies. The major challenge in CTC/DTC research is now to harmonise the various identification and detection approaches and consequently to conduct large prospective multi-institutional trials to verify the use of CTCs/DTCs as a valid prognostic and predictive biomarker for clinical routine.

Spontaneous changes in tumour cell dissemination to bone marrow in colorectal cancer

AIM

The study aimed to evaluate the incidence of disseminated tumour cells (DTCs) in bone marrow (BM) preoperatively and during follow up and to correlate these with established risk factors in patients with colorectal cancer.

METHOD

We prospectively studied BM in 57 patients using the anti-cytokeratin antibody A45-B/B3.

RESULTS

The overall detection rate of DTCs was 23% with a similar detection rate through all stages of the disease. No significant association was found between the presence of DTCs and clinicopathological parameters. After a median follow up of 35.4 months, no differences were found in relapse and overall survival between patients with and without DTC preoperatively. In 31 of 45 patients with local disease, we performed a follow-up BM examination after 1 year. In 26% of the patients, the BM status had changed as compared with the preoperative finding.

CONCLUSION

This is the first study to report the follow up of DTC in BM in colorectal cancer using the A45-B/B3 antibody. The presence of tumour cells in the preoperative BM had no impact on outcome. The BM status had changed after 12 months in a quarter of patients.

Clinical impact of different detection methods for disseminated tumor cells in bone marrow of patients undergoing surgical resection of colorectal liver metastases: a prospective follow-up study

Background

Large number of patients with colorectal liver metastasis show recurrent disease after curative surgical resection. Identification of these high-risk patients may guide therapeutic strategies. The aim of this study was to evaluate whether the presence of disseminated tumor cells in bone marrow from patients undergoing surgical resection of colorectal liver metastases can predict clinical outcome.

Methods

Sixty patients with colorectal liver metastases were planned for a curative resection between 2001 and 2007. All patients underwent bone marrow aspiration before surgery. Detection of tumor cells was performed using immunocytochemical staining for cytokeratin (CK-ICC) combined with automated microscopy or indirectly using reverse transcription-polymerase chain reaction (RT-PCR).

Results

Disseminated tumor cells were found in 15 of the 46 patients (33%) using CK-ICC and in 9 of 44 of the patients (20%) using RT-PCR. Patients with negative results for RT-PCR had a significant better disease-free survival after resection of their liver metastases (p = 0.02). This group also showed significant better overall survival (p = 0.002). CK-ICC did not predict a worse clinical outcome.

Conclusions

The presence of disseminated tumor cells in bone marrow detected using RT-PCR did predict a worse clinical outcome. The presence of cells detected with CK-ICC did not correlate with poor prognosis.

Review: Biological relevance of disseminated tumor cells in cancer patients

The prognosis of cancer patients is largely determined by the occurrence of distant metastases. In patients with primary tumors, this relapse is mainly due to clinically occult micrometastasis present in secondary organs at primary diagnosis but not detectable even with high resolution imaging procedures. Sensitive and specific immunocytochemical and molecular assays enable the detection and characterization of disseminated tumor cells (DTC) at the single cell level in bone marrow (BM) as the common homing site of DTC and circulating tumor cells (CTC) in peripheral blood. Because of the high variability of results in DTC and CTC detection, there is an urgent need for standardized methods. In this review, we will focus on BM and present currently available methods for the detection and characterization of DTC. Furthermore, we will discuss data on the biology of DTC and the clinical relevance of DTC detection. While the prognostic impact of DTC in BM has clearly been shown for primary breast cancer patients, less is known about the clinical relevance of DTC in patients with other carcinomas. Current findings suggest that DTC are capable to survive chemotherapy and persist in a dormant nonproliferating state over years. To what extent these DTC have stem cell properties is subject of ongoing investigations. Further characterization is required to understand the biology of DTC and to identify new targets for improved risk prevention and tailoring of therapy. Our review will focus on breast, colon, lung, and prostate cancer as the main tumor entities in Europe and the United States.

Detection and clinical implications of minimal residual disease in gastro-intestinal cancer

INTRODUCTION

Metastatic dissemination is an important factor for the prognosis of patients with gastro-intestinal cancer. Exact staging is crucial to determine appropriate multimodal therapeutic strategies. At present, the sensitivity of routinely performed diagnostic techniques is suboptimal for the detection of minimal residual disease (MRD) and occult metastases since the number of disseminated tumour cells (DTCs) is mostly marginal. To amend the verification of DTCs, immunohistochemical and molecular methods were applied to retrieve epithelial cell-specific proteins in non-epithelial tissue of different body compartments or fluids. Many groups have eagerly focussed on the identification of new markers and novel tests, yet specificity and sensitivity of these methods as well as robustness in the clinical setting are frequently missing.

MATERIALS AND METHODS

This review critically evaluates the prognostic impact of MRD in patients with pancreatic, colorectal and gastric cancer by outlining those studies showing diagnostic results of DTC detection in lymph nodes, bone marrow, venous blood and peritoneal lavage, some of which present novel strategies.

CONCLUSION

The analysed data concerning MRD in gastro-intestinal cancers reveal that results are undesirably heterogeneous. From a critical point of view, many clinical studies missed their chance because of small cohort size; moreover, methodological standardisation is generally lacking. On the other hand, the very encouraging results achieved so far, together with the comprehensive analyses of a few research groups, foster the prediction that DTC/MRD issues will soon expand the standard TNM classification.