A report on the B7-H3 molecule has been published in the journal Cancer Research.
"This discovery will allow physicians to individualize treatment and observation plans for prostate cancer patients. Being able to tell a patient his specific risk after surgery, and perhaps even prior to surgery, will be a huge step forward," says Dr. Timothy Roth, a Mayo Clinic urology resident and lead author of the study.
The new study attains significance because there were no strongly predictive molecules for prostate cancer to date. It shows that almost all normal, pre-malignant and cancerous prostate cells have B7-H3 on their surface.
Since the molecule stays attached to the surface of prostate cancer cells and does not migrate, it is being considered an attractive target for therapy.
The researchers believe that B7-H3 kills or paralyses immune cells that try to attack the cancer.
The researchers examined tissue from 338 consecutive patients who had cancers confined to the prostate and were treated exclusively with a radical prostatectomy (surgery to remove the prostate) between 1995 and 1998. All tumours and pre-cancerous tissues displayed B7-H3.
It was found that patients with the highest levels of B7-H3 within their prostate tumours (19.8 per cent) were four times more likely to experience cancer progression in comparison with those with weak levels of B7-H3 within their tumours. Moderate levels of B7-H3 also correlated with a slightly higher risk of recurrence (35 per cent).
"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," says Dr. Eugene Kwon, a senior investigator and urologist at Mayo Clinic.
A 'watchful waiting' clinical approach is sometimes used to manage prostate cancer for some patients, prior to resorting to therapy to see if the cancer becomes increasingly aggressive.
The researchers say that the evaluation of B7-H3 levels in prostate biopsies may soon help to determine which patients may benefit from a watchful waiting strategy.
"This is the way of the future," says Dr. Kwon, "We are becoming educated about ways to flesh out the molecular signatures of each patient's cancer. Using such molecular signatures will facilitate, for the first time, a truly individualized approach to prescribing the most appropriate therapy for a given patient. We will soon be able to tailor-make therapies for each person's cancer."