Detectable tumor cells in the blood and bone marrow: smoke or fire?

Liquid biopsy for monitoring of tumor dormancy and early detection of disease recurrence in solid tumors

Cancer is one of the three leading causes of death worldwide. Even after successful therapy and achieving remission, the risk of relapse often remains. In this context, dormant residual cancer cells in secondary organs such as the bone marrow constitute the cellular reservoir from which late tumor recurrences arise. This dilemma leads the term of minimal residual disease, which reflects the presence of tumor cells disseminated from the primary lesion to distant organs in patients who lack any clinical or radiological signs of metastasis or residual tumor cells left behind after therapy that eventually lead to local recurrence. Disseminated tumor cells have the ability to survive in a dormant state following treatment and linger unrecognized for more than a decade before emerging as recurrent disease. They are able to breakup their dormant state and to readopt their proliferation under certain circumstances, which can finally lead to distant relapse and cancer-associated death. In recent years, extensive molecular and genetic characterization of disseminated tumor cells and blood-based biomarker has contributed significantly to our understanding of the frequency and prevalence of tumor dormancy. In this article, we describe the clinical relevance of disseminated tumor cells and highlight how latest advances in different liquid biopsy approaches can be used to detect, characterize, and monitor minimal residual disease in breast cancer, prostate cancer, and melanoma patients.

Natural history and treatment of bone complications in prostate cancer

Bone metastases are highly prevalent in patients with prostate cancer, and they commonly present a therapeutic challenge. The natural history of prostatic bone metastases is characterized by skeletal morbidity, often producing distressing symptoms for individual patients and reducing patient autonomy and mobility. These bone metastases are usually radiologically osteoblastic, but there is also a strong osteolytic component as evidenced by marked increases in bone resorption markers. Malignant bone lesions can reduce the structural integrity of the skeleton, resulting in skeletal complications such as pathologic fracture, spinal cord compression, and severe bone pain, which adversely affect quality of life. Preclinical and clinical studies have provided insight into the pathophysiology of malignant bone disease from prostate cancer and suggest that bone-directed therapies, including radionuclides, endothelin-1 antagonists, and bisphosphonates, may provide both palliative and therapeutic benefits. Clinical investigations with these agents are underway in patients with prostate cancer to gain insight into the pathophysiology of bone metastases and to evaluate the role of bone-specific therapies in treating and preventing bone metastases.

Preliminary study of immunomagnetic quantification of circulating tumor cells in patients with advanced disease

OBJECTIVES

To enumerate the amount of circulating tumor cells (CTCs) in patients with advanced prostate cancer and to investigate the relationship between these numbers, prostate-specific antigen (PSA) and prostate-specific membrane antigen (PSM) expression, and clinical parameters.

METHODS

Whole blood was collected in proprietary CellSave tubes. Mononuclear cell fractions were isolated using epithelial cell antibody-coated magnetic nanoparticles. On one half of each immunomagnetically enriched cell fraction, automated fluorescent microscopy was used to identify the epithelial tumor cells. From the remainder of each sample, RNA extraction, cDNA synthesis, and polymerase chain reaction amplification of PSA and PSM were performed.

RESULTS

Eighty-four patients with advanced prostate cancer submitted 130 samples for analysis. Intact CTCs were identified in 62% of samples; 83.3% of CTC-positive and 0% of CTC-negative samples were reverse transcriptase-polymerase chain reaction positive for PSA and PSM (P = 0.001). A significant positive correlation was found between the CTC number and PSA (r = 0.49), alkaline phosphatase (r = 0.47), and lactate dehydrogenase (r = 0.55) levels, and a significant negative correlation with hemoglobin (r = -0.35). The initial Gleason grade, prior therapy, current therapy, and type of metastasis (bone, soft tissue) did not correlate significantly with the CTC number.

CONCLUSIONS

The presence of intact CTCs and the expression of PSA and PSM demonstrated robust agreement. The tumor cell numbers reflected current disease status and correlated significantly with the clinical disease indicators of PSA, hemoglobin, and liver function tests. These findings warrant further investigation of the diagnostic and prognostic value of enumerating intact CTCs.

Prostate carcinoma: defining therapeutic objectives and improving overall outcomes

The development and progression of a prostate carcinoma from prediagnosis to death can be characterized as a series of clinical states. The states are milestones that can be used to assess prognosis, define therapeutic objectives, and assess outcomes. The antitumor effects of hormone therapies and cytotoxic agents in patients with prostate carcinoma are placed in context along with the bidrectional tumor-host interactions that contribute to the growth and resistance of osseous lesions. Identifying the factors that contribute to the growth of the disease at different points in the illness has lead to novel, systemic approaches. Proving the benefit of these approaches requires a series of unique trials with unique endpoints relevant to the clinical state of the patients and the specific therapy under evaluation.

Correlation of tumor size and survival in patients with stage IA non-small cell lung cancer

OBJECTIVE

The purpose of this study was to determine the relationship between tumor size and survival in patients with stage IA non-small cell lung cancer (non-small cell lung cancer; ie, lesions < 3 cm).

METHOD

Five hundred ten patients with pathologic stage IA (T1N0M0) non-small cell lung cancer were identified from our tumor registry over an 18-year period (from 1981 to 1999). There were 285 men and 225 women, with a mean age of 63 years (range, 31 to 90 years). The Cox proportional model was used to examine the effect on survival. Tumor size was incorporated into the model as a linear effect and as categorical variables. The Kaplan-Meier product limit estimator was used to graphically display the relationship between the tumor size and survival.

RESULTS

The Cox proportional hazards model did not show a statistically significant relationship between tumor size and survival (p = 0.701) as a linear effect. Tumor size was then categorized into quartiles, and again there was no statistically significant difference in survival between groups (p = 0.597). Tumor size was also categorized into deciles, and there was no statistical relationship between tumor size and survival (p = 0.674).

CONCLUSIONS

This study confirms stratifying patients with stage IA non-small cell lung cancer in the same TNM classification, given no apparent difference in survival. Unfortunately, these data caution that improved small nodule detection with screening CT may not significantly improve lung cancer mortality. The appropriate prospective randomized trial appears warranted.