Detection Of Circulating Tumor Cells In Breast Cancer Patients By CK19 MRNA

Breast cancer is the No.1 malignancy that threatens women's health. About 1,200,000 new cases of breast cancer are diagnosed each year and nearly 500,000 women died of breast cancer per year. Its morbidity in shanghai is 38/100,000 in 1995, the most common type of cancer among women in Shanghai.Mostly, breast cancer cells originate from mammalian ductal epithelium. Cancer cells can break away from a malignant tumor and enter the bloodstream or the lymphatic system. That is how cancer spreads from the original (primary) cancer site to form new tumors in other organs. The spread of cancer is called metastasis. Once cancer cells have gained access to either the lymph channels or the blood stream, they have the potential to spread to any area of the body. In breast cancer, these areas are typically the bone, the lungs, the liver and the brain. Metastasis is the main reason for death of breast cancer patients. The goal of breast cancer staging is to classify patients by the extent of disease into groups with similar clinical outcomes. Staging facilitates patient management, allowing clinicians to tailor therapies to individual patients. Unfortunately, current staging for breast cancer is invasive, expensive, and lacks sensitivity. Breast cancer staging is based on the AJCC TNM system, which relies heavily on the pathological evaluation of the primary tumor, regional lymph nodes, and distant metastases. Within this framework, the presence of disease in the ALN (axillary lymph nodes) is an important prognostic indicator for breast cancer patients. As a result, staging for newly diagnosed clinical stage Ⅰand II breast cancer patients typically includes an ipsilateral axillary lymph nodes dissection or sentinel lymph node biopsy. Despite the application of this relatively invasive and expensive staging procedure, up to 30% of node-negative patients ultimately develop recurrent disease. This suggests that the tissue being sampled and /or the means of disease detection are inadequate. Additionally, the detection of distant metastatic disease in breast cancer patients is also problematic. Presently, clinicians will obtain a staging evaluation that includes computed tomography of the chest, abdomen, and pelvis and a nuclear medicine bone scan as the clinical situation indicates. However, such an evaluation is limited by expense and low sensitivity.The recent identification of genes overexpressed in breast cancer, combined with advances in molecular biology, provides the opportunity to establish more sensitive, specific, and cost-effective ways of identifying metastatic disease. Among the current possibilities, one of the most compelling is the development of a sensitive molecular diagnostic assay for the detection of breast cancer in the peripheral blood. Such an assay could potentially replace invasive procedures such as ALN dissection and /or be used for breast cancer screening and monitoring treatment responses. Unfortunately, molecular analysis of peripheral blood has proven more challenging than that of other tissue compartments. mRNA is relatively unstable in peripheral blood, and the presence of hemoglobin can inhibit the PCR reaction. Other issues include the relatively low concentration of circulating breast cancer cells and false-positive results in normal blood attributed to contamination with skin cells at venipuncture or to illegitimate transcription in peripheral blood leukocytes.The intermediate filament protein CK19 is a specific epithelial marker that is normally not expressed in lymphoid or hematopoietic tissues. CK19 mRNA detected by RT-PCR has been used as an index of disseminated tumor cells in blood, bone marrow, and lymph nodes in patients with breast cancer and other epithelial cancers including lung, pancreas, and stomach. In preliminary experiment, we used strict precautions to avoid contamination with skin cells at venipuncture and an optimally calibrated assay to eliminate false–positive in control blood samples (0/10). We then applied the assay to blood samples from 77 patients wi...