March 7, 2005
by Emily Carlson

Two men of the same age have been diagnosed with an advanced stage of prostate cancer. Both individuals follow their doctors' advice and undergo surgery to remove the malignant walnut-sized gland, which is involved in male reproduction. Although the patients are similar clinically, they may face different futures because the tests used to detect the cancer are poor predictors of whether the disease will return after removal. However, a close look at a protein present in many types of cancer cells reveals a new tool for forecasting a man's risk of prostate cancer recurrence.

Kun Ping Lu, M.D., Ph.D., of Beth Israel Deaconess Medical Center in Boston, Massachusetts, has spent years studying the protein Pin1, which helps regulate the growth and division of cells. He had previously shown that some types of cancerous tissue contain increased levels of Pin1.

Lu wondered if the Pin 1 levels he found in prostate cancer cells might signal the recurrence of the disease following surgery. To test this idea, he measured the amount of Pin1 contained in the malignant tissue removed by a single surgeon from hundreds of men diagnosed with prostate cancer. Lu then followed up with 580 of the men to find out if they were still cancer-free. This work revealed a link between levels of Pin1 at the time of surgery and prostate cancer recurrence. In fact, the higher the level of Pin1, the more likely it was that the disease would come back.

This finding suggests that doctors could measure Pin1 levels to predict their patients' chances of prostate cancer recurrence and to tailor the treatment plan. The results also indicate that drugs might be developed to suppress Pin1 levels, possibly preventing disease recurrence and further helping doctors manage what is now the most common cancer among American men.