Researchers at the UCLA Jonsson Comprehensive Cancer Center analysed gene-expression patterns in the most aggressive prostate cancer grade group -known as Gleason grade group 5 - and found that this grade of cancer can actually be subdivided into four subtypes with distinct differences.

The findings, published in European Urology may affect how people are treated for the disease.

One subtype, which accounts for about 15% of the grade group 5 cancers, has highly aggressive features and is associated with much worse outcomes than the other subtypes.

Another, which makes up about 20% of the tumours, appears to be much less aggressive and may not require intensified and aggressive treatments.

Traditionally, all tumours in Gleason grade group 5 have been treated in the same way.

Prostate cancer is the leading solid-tumour cancer among men in the United States and a major cause of morbidity globally.

While early-stage, localised prostate cancer is curable, current treatments don't always work for everyone.

To find out why standard treatment may work for some and not others, the UCLA researchers looked at tumours in the Gleason grade group 5 subset of prostate cancer.

These tumours are at the highest risk to fail standard treatment, leading to metastasis and death.

The researchers thought that studying the gene expression - the unique "signature" - of each cancer cell in these tumours might provide insight into how to make treatments more personalised for each patient.

The researchers first analysed data from more than 2,100 Gleason grade group 5 tumours, looking at how the genetic blueprints differed among the tumours.

They identified distinct clusters of subgroups and validated their findings by analysing an additional cohort of more than 1,900 Gleason grade group 5 prostate cancers.

By using the genetic information from tumours in men with prostate cancer, physicians hope to one day create more personalised treatments based on the actual characteristics of the cancer.

This information will help optimise quality of life and avoid over-treating subgroups of men who may not need aggressive treatments.

Source: University of California - Los Angeles Health Sciences