New marker for prostate cancer gives hope for more accurate
diagnosis than PSA test
18 May 2011
Researchers at Uppsala University have discovered a promising
new marker for diagnosing prostate cancer.
The research team, led by Professor Ulf Landegren of the
University's Department of Immunology, Genetics, and Pathology,
discovered a unique method for detecting prostate cancer that could
lead to more reliable diagnoses and fewer unnecessary operations.
The study has been published in the Proceedings of the National
Academy of Sciences (PNAS),
The PSA test that is currently commonly used for diagnosing
prostate cancer has been criticized for giving false positive
responses, leading to unnecessary operations. There is therefore
great interest in finding new and better biomarkers.
Masood Kamali-Moghaddam, a member of the research team, said, "In
the limited patient material examined in the study, blood levels of
so-called prostasomes seem to correlate more closely with the
severity of the disease than do PSA levels."
The team has previously developed a uniquely specific and
sensitive method, called proximity ligation, for effective
determination of proteins, and the method has now been adapted for
One of the co-authors of the present study, Professor Gunnar
Ronquist, showed 30 years ago that prostate cells pump out large
quantities of a tiny membrane-coated particle in semen, which he
named prostasomes. The hypothesis is that, in cancer, rather than
winding up in semen, prostasomes are pumped out into the surrounding
cancer tissue in invasive cancer. Therefore, prostasomes could be
expected to occur at elevated levels in blood in cases of prostate
It was not possible to detect prostasomes in blood peviously, but
the researchers devised a unique test that requires several
different antibodies to simultaneously recognize proteins on the
surface of the prostasomes, and this allowed them to detect elevated
levels of prostasomes in the blood of patients with prostate cancer.
“We are hopeful that this type of marker will prove valuable not
only for prostate cancer but also in several other common tumor
types,” says Masood Kamali-Moghaddam.
1. Gholamreza Tavoosidana et al. Multiple recognition
assay reveals prostasomes as promising plasma biomarkers for
prostate cancer. PNAS 2011; published ahead of print May 9,