Researchers at the Stanford Cancer Institute and the Cancer Prevention Institute of California (CPIC) have laid the groundwork for a comprehensive database that will contribute to earlier detection of cancer through blood tests, through soliciting tens of thousands of blood samples.
More than 50,000 female teachers and school administrators around California were recently approached about submitting blood samples to the database. According to Tina Clarke, a CPIC research scientist and a member of the Stanford Cancer Institute, about 25,000 people are expected to agree to blood sampling.
Clarke said that those willing to participate will be asked to fill out five detailed questionnaires and schedule an appointment to get their blood drawn. Their blood samples will be frozen in a biobank and analyzed over time to see whether there are similarities among the blood samples of those subjects who eventually develop cancer.
“We store samples from women who are healthy, but also at the age where cancer rates are high,” Clarke said. “If they develop cancer later on in life, we can go back to these samples and look for early markers of cancer.”
The effort is part of the California Teachers Study, which collected data on more than 133,000 current and former public school teachers and administrators through questionnaires in 1995 and 1996.
Researchers have stayed in contact with the participants to determine whether or not their answers to questions about their lifestyle, health and medical history correlate with the probability of cancer incidence.
Since the study initially sought to investigate breast cancer, the participants are all female, although researchers hope to use the samples for the early detection of other kinds of cancer as well.
Professor of Urology James Brooks M.D. ‘88, who is also a member of the Stanford Cancer Institute, said that the process of using blood tests for the early detection of cancer is “very challenging,” as it involves finding blood markers that are both sensitive and specific to cancer.
“By sensitive, I mean you need to find the cancer when it’s curable,” Brooks said. “Sometimes that means finding a cancer that is one cubic centimeter—the size of a sugar cube—in order to make a big difference in the number of women dying of ovarian cancer.”
According to Brooks, finding such markers is no easy feat, as many of the proteins that indicate the presence of cancerous cells are also signals of other diseases. Once those markers are identified, researchers can run tests on the biobank’s collection of old blood samples to determine which components predict cancer’s onset.
However, though DNA sequencing technologies capable of finding mutations that signify the presence of certain types of cancer currently exist, the technologies are still too expensive to be used regularly and need refinement before they can be incorporated into reproducible clinical tests.
According to Clarke, it will likely take 15 to 20 years, as well as the right expertise, for the study’s “exciting vision” of allowing early cancer detection through blood tests to be translated to reality.
Researchers nonetheless emphasized the study’s significance, noting that it can be linked to other databases and participants’ information updated as long as they continue to reside in California.
“What CPIC has put together is very valuable, and will get more valuable with the passing of time,” Brooks said. “People underestimate how hard and expensive this is to do.”