Two separate genetic signatures seem to be able to tell how severe a patient’s prostate cancer is going to be, which would dramatically improve prognoses and make it easier for doctors to decide on the most appropriate treatment early on, American and British researchers report in two articles published today in the journal The Lancet Oncology.

The authors explain that unique RNA patterns seem to be able to predict the course of prostate cancer, pointing either towards an aggressive disease or a milder form. RNA (ribonucleic acid) is the genetic material that helps convert DNA into proteins.

Prostate cancer affects patients in many different ways. Some develop the disease and do not know because they have no symptoms, some may respond extremely well to treatment, while others have types that resist all treatment and progress regardless.

Castration-resistant prostate cancer does not respond to standard androgen deprivation therapy. Survival times with this type of cancer vary considerably from patient-to-patient. Nobody really knows why.

Current diagnostic tests can tell, to a certain extent, whether or not a prostate cancer is likely to be an aggressive one. However, their accuracy can only be described as “moderate”.

Not only would an accurate predictor of a prostate cancer help with better prognoses, but it would also improve the quality of clinical trials for new therapies. Patients in the trials themselves could be selected into aggressive cancer groups and mild groups.

Lead scientist, Professor Johann de Bono, at The Institute of Cancer Research, London, and The Royal Marsden NHS Foundation Trust in the UK, and team identified a set of genes which could predict whether a patient had castration-resistant prostate cancer.

A distinctive nine-gene pattern which was linked to castration-resistant prostate cancer patients was accurately detected – those patients survived for an average of 9.2 months after referral for treatment, compared to those without the genetic pattern who survived for 21.6 months.

Research head, Professor William Oh, at the Tisch Cancer Institute of Mount Sinai School of Medicine in the USA, and team found another set of genes that could predict the course of prostate cancer in a similar way to those identified in the first article.

They identified a set of six genes linked to an aggressive form of prostate cancer in 62 patients at the Dana-Farber Cancer Institute, Boston, USA.

The signature accurately divided the patients into the high-risk group with a survival time of 7.8 months, and the low-risk group with 34.9 months survival time. They used a validation cohort of 140 patients to confirm their findings.

The authors explained that genetic signatures have been identified in previous studies, but only to classify types of prostate cancer, rather than make predictions regarding the course of the disease.

These two studies are the first to show that it is possible to make accurate prognoses by using genetic signatures.

In previous studies, genetic tests could only be carried out by taking material from the tumor. Even then, prognosis is not very reliable, because individual patient responses to prostate cancer vary considerably.

In these two latest studies, the genetic signatures were identified from straightforward blood tests.

In a Comment in the same journal, Dr Karina Dalsgaard Sørensen at Aarhus University Hospital in Denmark, wrote:

“Scarcity of prognostic markers presents a major challenge for the clinical management of castration-resistant prostate cancer. These results suggest that a few selected genes in blood samples from patients with castration-resistant prostate cancer can significantly improve the prediction of outcomes.

However, the biological relevance of these prognostic signatures, which are the first of their kind, is largely unknown and further investigation into the underlying biological mechanisms at work here could greatly advance our understanding.”

Written by Christian Nordqvist