A 70-gene-expression metastatic assay biomarker could change how physicians determine treatment plans for patients with prostate cancer.
Prostate cancer is unique in that some tumors may cause no clinical symptoms and pose little or no risk to a patient’s life. Physicians use active surveillance to monitor these tumors, which require further treatment only if they shows signs of progression. That saves patients from side effects associated with radiation and chemotherapy.
However, the issue is knowing which tumors are likely to progress at what rate. Current techniques do not always make that clear, and if the cancer is more aggressive than physicians initially deduced, patients may have forfeited the benefits of early, aggressive treatment.
A Chance to Improve Diagnosis?
Developed at Queen’s University Belfast, in Northern Ireland, the metastatic assay has been the focus of recent studies aimed at improving prognostic and diagnostic procedures related to prostate cancer.
A study published in European Urology hypothesized that the assay “may improve the ability to detect patients at risk of metastatic recurrence following radical prostatectomy.” Based on these findings, Suneil Jain, MD, PhD, Senior Lecturer at Queen’s University Belfast and Consultant Oncologist at the Belfast Trust, spearheaded a new study.
Published in Annals of Oncology, this study examined the assay’s performance in diagnostic biopsies from patients who had undergone primary radiation therapy and androgen deprivation therapy.
“The current study shows that patients who were biomarker-positive — even when you considered standard clinical variables — were about three times as likely to develop metastatic prostate cancer after primary treatment with radiation therapy and androgen deprivation therapy,” Dr. Jain says. “The rate of metastases-free survival at 10 years from initial treatment was 94 percent in patients who were metastatic assay-negative and 72 percent for patients who were metastatic assay-positive.”
The assay may enhance diagnosis of prostate cancer’s likely aggressiveness if physicians can test for the biomarker early, enabling them to make a more informed decision about whether to pursue active surveillance or more aggressive treatment.
An Uncertain Path
It is too early to say whether metastatic assay will become a common diagnostic tool, however. Existing diagnostic procedures include prostate-specific antigen (PSA) tests and grading the appearance of prostate cancer using a Gleason score.
“You’re always going to have variability for any given grade or number of metastases in predicting the actual survival and response to treatment, but [current methods] are pretty good,” says Ian F. Tannock, MD, PhD, Emeritus Professor of Medical Oncology at Princess Margaret Cancer Centre in Toronto, Ontario. “The grade you find in a biopsy gives you a reasonable angle on aggressiveness. If you have a man you suspect has metastatic prostate cancer and his PSA is high, he will have a bone scan, and likely a CT scan, and a biopsy ... and that should give you a fair bit of information.”
Dr. Jain is cautiously optimistic.
“We want to pick the right patients for intensified treatment,” he says. “If we could develop biomarkers that give us more confidence that a cancer was truly indolent, that would help us pick the right patients for active surveillance.”