NORFOLK, VirginiaUsing an innovative technique called protein chip mass spectrometry, researchers at Eastern Virginia Medical School in Norfolk have identified specific serum protein profiles that may enhance the detection of breast cancer. Lori Wilson, MD, previously research associate at Eastern Virginia Medical School and now surgical oncology fellow at John Wayne Cancer Institute in Santa Monica, California, reported that in early testing, the biomarker profiles have shown a specificity and sensitivity that approaches that of mammography.
Protein chip mass spectrometry searches for multiple differentially expressed proteins to create unique protein profiles. For their study, the researchers used Surface-Enhanced Laser Desorption/Ionization (SELDI)/Time of Flight (TOF) mass spectrometry. They applied the SELDI/TOF technology to sera collected through the division of surgical oncology from both healthy women and women with breast cancer.
"Our samples were prospectively collected and were pretreatment as well as from normal healthy patients," Dr. Wilson said. "We analyzed 139 female sera by our SELDI technology, and the clinicopathologic information was recorded in our breast study data base."
Patient samples were classified as normal/benign or cancer. The median age was 46.5 years in the normal/benign patients and 59.3 years in the patients with breast cancer. The overall age range was 21 to 91 years. Eighty percent of the breast cancer patients were staged as ductal carcinoma in situ (DCIS) or stages I or II. Only 13% were stage III and 7% were stage IV.
Serum Sample Processing
"In serum sample processing for the SELDI analysis, we initially used the IMAC copper chip but decided to use the SAX chip to increase the number of proteins that were resolved with the mass spectrometry. We noted that with two chips there were peaks that were conserved but also peaks that we could isolate on one chip or the other," Dr. Wilson said.
Those samples were similarly processed through denaturing in the presence of urea(Drug information on urea) buffer and were applied onto the chip in duplicate and randomized, she added. The nonspecific proteins were washed away with binding buffer, and then the data analysis and peak labeling were performed with Wizard Biomarker Software.