Prostate tumors that contain more of a specific type of cell are more likely to be life-threatening, a new study has found. The research could lead to a test to differentiate between aggressive and harmless forms of the disease.
Prostate cancer is the most common cancer affecting males in the United States.
According to the American Cancer Society, around 1 in 9 men will receive a diagnosis of the disease in their lifetime. However, only 1 in 41 of those diagnosed will die as a result of it.
In many cases, doctors cannot determine the severity of a person’s cancer.
Every year, this uncertainty affects around 250,000 males newly diagnosed with the disease in Europe and North America.
Doctors and individuals with the disease face a significant dilemma when deciding whether to treat the disease or adopt a “watch and wait” approach.
Professor Colin Cooper, who jointly led the new research at the University of East Anglia’s (UEA) Norwich Medical School in the United Kingdom, explains:
“[Prostate cancer] usually develops slowly, and the majority of cancers will not require treatment in a man’s lifetime. However, doctors struggle to predict which tumors will become aggressive, making it hard to decide on treatment for many men. This means that many thousands of men are treated unnecessarily, increasing the risk of damaging side effects, including impotence from surgery.”
Doctors use the prostate-specific antigen (PSA) test to screen older men for prostate cancer.
Studies suggest that population-wide PSA screening is worthwhile, reducing overall mortality from prostate cancer by 21%.
Nonetheless, the majority of prostate cancers that doctors diagnose as a result of PSA tests progress slowly and do not spread to other parts of the body. As a result, these men will usually die in old age of something else.
Ideally, doctors would reserve the more radical treatments, such as surgery and radiotherapy, for those men with the most aggressive cancers.
In a previous study, the UEA team took a significant step toward addressing this problem by identifying a cell type associated with poor outcomes in prostate cancer.
Their new study, published in the British Journal of Cancer, indicates that tumors with the highest number of these cells are likely to progress more rapidly. This is due to an increased metastatic risk.
The scientists hope that these findings will lead to the development of tests to determine who needs immediate treatment and who requires monitoring.
Prostate tumors contain a variety of cell types, each posing a different level of risk.
The UEA scientists set out to develop a classification system for the most common cell types based on patterns of gene activity, known as “gene expression pattern.”
Their previous research used some complex math called Latent Process Decomposition to identify the unique molecular signature of an aggressive expression pattern they call DESNT.
In their new work, they analyzed patterns of gene expression in 1,785 tumor samples. They then correlated the amount of DESNT in each tumor sample with the outcome of the disease for that individual.
The researchers found that the more DESNT cells a sample contained, the more likely it was that the cancer would metastasize.
At the same time, the researchers identified three other prostate cancer molecular subtypes, making it a total of four categories of gene expression patterns in prostate cancer.
In the future, they hope to develop a classification system based on the four cell types that will not only help identify people whose cancers will metastasize but also predict their response to different drug treatments.
They note that a similar classification system for breast cancer has been developed using the same mathematical technique and is already being used to guide treatment.