Health disparities: genetics plays an important role in cancer detection, prognosis among minorities

Between 2000 and 2002, the rate of invasive breast cancer among Caucasians was stable. The greatest reduction, 2.41 percent per quarter, was seen toward the end of 2003. In the same year, the rate of invasive breast cancer among African-American women increased 0.07 percent per quarter, decreased 0.14 percent per quarter in American Indian/Alaskan Natives and decreased 0.46 percent per quarter in Asian American/Pacific Islanders.

For the rate of in situ breast cancer, an early stage disease, the rate was stable among Caucasians, African Americans and American Indian/Alaskan Natives. Among Asian American/Pacific Islanders, the rate of in situ breast cancer increased slightly from 2000 to mid 2002 by 2.09 percent per quarter, and decreased by the end of 2004 by 3.2 percent per quarter.

Application of nanotechnology for enhanced early detection of prostate cancer in African-American men: Abstract 4741

Once limited to the electronics industry, semiconductor material may hold the key to improving the detection of prostate cancer among African-American men. Nanotechnology using quantum dots made from semiconductor material allowed researchers to detect the presence of six biomarkers associated with prostate cancer.

If proven in clinical studies, the nanotechnology will enable physicians to diagnose prostate cancer at earlier stages, which is particularly important for African-American men.

“African-American men appear to have the highest rate of prostate cancer incidence in the world,” said Catherine M. Phelan, M.D., Ph.D., an assistant professor in cancer prevention and control at H. Lee Moffitt Cancer Center & Research Institute in Tampa, Fla. “ In addition, their prostate cancer mortality rate is twice as high as the rate for white Americans.”

Early detection is crucial. Among African-American men diagnosed with early stage prostate cancer, five-year survival rates are almost 100 percent. For men diagnosed with more advanced disease, five-year survival rates are 29 percent, according to Phelan.

To improve early detection, Phelan and her colleagues investigated quantum dot antibody conjugates. Quantum dots (QD) measure 5-20 nanometers in diameter. For comparison, a human hair measures 100,000 nm in diameter. The small size of the QDs results in new optical properties that allow observers to determine the size and energy of the QD and where it will emit light along the color spectrum.

“Smaller QDs are higher energy and emit in the blue part of the spectrum, whereas the larger-sized but lower-energy QDs emit light in the red part of the spectrum,” Phelan explained.

“If you want to look at a particular known protein in the blood, such as prostate specific antigen (PSA), you can attach the specific antibody for that protein to the QD and, using a laser, observe where the emission peak lies in the color spectrum. The height of the peak represents the amount of protein in the blood sample,” she said.