For men older than about 60, an enlarged prostate means feeling the urge to make a pit stop way too often throughout the day.

But a new study shows that if these men also happen to have prostate cancer, the larger prostate actually impedes tumour growth.

The findings suggest that it might be a bad idea to downsize an enlarged prostate through surgery or drugs, as doing so could lead to faster growth of prostate cancer.

While the five-year survival rate for prostate cancer is generally very high, it is still one of the leading causes of death among men in the U.S. - according to the Prostate Cancer Foundation.

Computer simulations of patient data offer a possible explanation of why an enlarged prostate might be a lifesaver - because a prostate can only grow so much within a confined space, force accumulates and exerts pressure on the tumour which effectively keeps it small. 

"It's already known that forces and stresses have an impact on tumour growth and that patients with enlarged prostates tend to have slower cancer growth, but it wasn't known why," said Hector Gomez, associate professor of mechanical engineering at Purdue University, who builds models and simulations for understanding tumour growth, cellular migration and blood flow.

The study, which has been published in the Proceedings of the National Academy of Sciences, is the first to simulate the possible effects of benign prostatic hyperplasia - a disease that causes the prostate to enlarge progressively on the tumours of prostate cancer.

Guillermo Lorenzo, a former doctoral student of Gomez who is now a postdoctoral researcher at the University of Pavia in Italy, performed most of the research and ran the simulations.

Alessandro Reali and Pablo Dominguez-Frojan also participated in the study and are coauthors of the paper.

Gomez and Thomas Hughes, a professor of aerospace engineering and engineering mechanics at The University of Texas at Austin, began the project as part of their work on using computer simulations to improve the diagnosis and prognosis of prostate cancer.

"Current diagnosis and prognosis methods have had a hard time differentiating between patients who are under serious risk of prostate cancer and those who aren't," Gomez said. "This has led to people getting overtreated or undertreated."

Looking at the relationship between prostate enlargement and prostate cancer could bring new insights.

The study looked at data from patients in medical studies who had a history of both an enlarged prostate and prostate cancer.

To perform the simulations, Lorenzo extracted a three-dimensional anatomy of the prostate and locations of the tumours from MRI images.

At the end of a one-year period, the simulations showed that the tumour of a patient with a history of an enlarged prostate barely grew at all.

When the researchers removed the history of an enlarged prostate in the program, the tumour had grown to be over six times larger at the end of the same time period.

"But now we know that the mechanical stresses that originate as prostates enlarge impede tumour growth," Hughes said.

Realistically, these findings would need to be clinically validated in humans through a long-term observational study before doctors take action.

In the meantime, the researchers plan to extend their model to incorporate the effects of drugs that downsize the prostate, as well as use the model's information on the deformation of the prostate to help detect cancer.

Source: Purdue University

Photo credit: Guillermo Lorenzo, University of Pavia