A molecule that plays a key role in prostate cancer development — and can predict recurrence — has been identified by researchers at the Mayo Clinic in Rochester, Minn.

The report on the B7-H3 molecule appears Wednesday in the journal Cancer Research.

Researchers believe that B7-H3 kills or paralyzes immune cells that are trying to attack the cancer, allowing the prostate tumour to grow.
(CBC)

In the study, Mayo researchers found that almost all normal, pre-malignant and cancerous prostate cells have B7-H3 on their surface.

To date, the only biological markers for prostate cancer have been the prostate-specific antigen (PSA), which Canadian men are screened for beginning at age 50, and the prostate-specific membrane antigen.

Researchers believe that B7-H3 kills or paralyzes immune cells that are trying to attack the cancer. Their findings indicate that B7-H3 may prove to be a diagnostic, prognostic and even therapeutic tool because it is increasingly displayed by tumour cells as prostate cancers develop.

"Because B7-H3 is present in all prostate cancer tumors, and marked levels predict recurrence, we are able to forecast with much greater certainty the likelihood of cancer progression, regardless of therapeutic intervention," said Eugene Kwon, a senior investigator and urologist at Mayo Clinic, in a release.

Researchers examined tissue from 338 men who had cancers confined to the prostate and were treated solely with a radical prostatectomy (surgery to remove the prostate) between 1995 and 1998.

They found that increasing levels of B7-H3 indicated a four-fold increased risk of cancer recurrence after surgery. The estimated cancer survival rates at five years after surgery were 92 per cent for those with tumours that had weak B7-H3 intensity, 86 per cent for those with moderate B7-H3 intensity and 55 per cent for those with high B7-H3 intensity.

The researchers say that the evaluation of B7-H3 levels in prostate biopsies from patients may soon help to determine which patients may benefit from a watchful waiting strategy versus early aggressive treatment.

"This is the way of the future," said Kwon, "We are becoming educated about ways to flesh out the molecular signatures of each patient's cancer. We will soon be able to tailor-make therapies for each person's cancer."