Research Of Diagnosis For Early Beast Carcinoma By Surface Enhanced Laser Desorption/Ionization-Time Of Flight-Mass Spectrometry

Background and ObjectiveThe breast cancer is one of the most female common malignant tumors, and the incidence and mortality rate of the female breast cancer achieve the first rank and the second rank during 1995 and 2004[1]. According to the data of Chinese tumor registry office, the breast cancer was the first rank incidence of the female cancer in 2004, and the mortality rate of the breast cancer achieved the forth rank[2]. Because the diease of most of patients had progressed to the medium-term or terminal phase, there were no obvious improvement of the 10-year survial rate of the breast cancer. During the progress of the breast cancer, the pre-clinic phase was the longest, which nearly occupied the two-third of the disease entire course. As a result, the discovery of sensitive early breast cancer diagnosis would be important sense to the therapy of breast cancer, improvement of prognosis and survival quality.By the conventional mammary gland examination, including x-ray, B ultrasonic, infrared ray, selective galactophore canal opacification and cytological examination, 57-85% of the patients with obvious tumeur could be diagnosed exactly. All of these examination was not suitable to the patients with the less than 0.5cm tumeur, especially the early breast cnacer patients without touchable tumeur, because the sensitivity and positive rate and the correct rate of these examination was low. So it is clinic urgent requisition that was high sensitive and specific early diagnosis method of breast cancer. The development of differential proteomics would provide the new research method to the cancer research. During pathological progress, the tumor cell must produce different protein compared with normal tissue cell. If the different proteomics could be analyzed correctly, the new cancer diagnosis method shoud be found. Surface enhanced laser desorption/ionization time of flight mass spectrometry(SEDLI-TOF-MS) was developed recently as a kind of proteomics research method. SELDI protein chip could combine most of protein in sample non-specificity or specificity. During the protein was bombarded, most of combined protein were desorpted and formed gasified ions. According to the different flight time of different mass charge ratio in the electric field, different mass charge ratio and different contents protein could be represented directly as different position and height peaks via acceptance device and digital-analog conversion. By using that technology, many raw biological specimen, such as serum, urine, cell lysate, could be deteced directly with hight sensitivity and high through advantage to reflect the fulll view of protein in the sample, Then any changes of protein would be found to provide possiblity of early diagnosis, prognosis estimation and monitoring recurring or metastatic tumor. In our research, the serum of early breast cancer patients, mammary gland nonmalignant patients and healthy people was detected by SELDI-TOF-MS and IMAC30-Cu+, and it wasa determined whether there was classification model which coμld be used to diagnose the early breast cancer.MethodAll the serum samples(46 breast cancer patients, 40 mammary gland nonmalignant patients and 40 healthy people) were applied to immobilized metal affinity capture (IMAC30-Cu2+) protein chips to generate mass pectra by surface enhanced laser desorption/ionization- time of flight- mass spectrometry (SELDI-TOF-MS). Protein peaks identification dectection and clustering were performed using the Biomarker Wizard software and Biomarker pattern software, and the classification model of early diagnosis breast cancer could be constructed by cross validation method. Then another sample(including 10 healthy people, 10 breast cancer and 10 mammary gland nonmalignant patients) was double-blind tested to verify that classification model.ResultsAccording to the result of Biomarker Wizard software, the contents of 22 protein were different significantly(P<0.05). And all of the 22 protein contents in the early breast cancer serum were lower than that in healthy people serum. Based on the analysis of Biomarker Pattern software, the best classification model was established, which contained 10 protein(M3162.32,M3960.93,M4213.3,M4526.43,M5908.15,M5386.11,M11383.4,M11735.4,M13892.1,M6007.7), achieving a correct classification ratio and specificity of 98.41% and 97.5% respectively. The double-blind test reults showed that sensitivity and specificity to classifying the early breast cancer were 80% and 85%.ConclusionsThere contents of 22 protein in the early breast cancer were significantly lower than that of healthy people. It suggested that these protein maybe inhibited or degraded during the tumorigenesis process, or these protein lower contents directly or indirectly lead to tumorigenesis.The early diagnosis model of breast cancer which was established by using SELDI-TOF-MS was highlier sensitive than the conventional mammary gland examination. If the diagnosis model was verified through large clinic experiment, the SELDI-TOF-MS was expected to be a new diagnosis method. In addition, that diagnosis model woμld be applied to the breast cancer census.