When diagnosed I was told that I had a Gleason score of 7, calculated by adding the first number, a descriptor of the most prevalent cancer cells in the biopsy sample, to the second number, a descriptor for the second most prevalent cancer cells. In my case the actual Gleason score was 4+3 or a 7. It would also have been possible to have had a 7, but instead calculated by a 3+4.

As the cells become more differentiated (or more aggressive and progressed) the assigned Gleason number increases, so a 4 reflects a more advanced and aggressive disease pattern than a 3. So, Is there a difference between a 7 calculated from a 4+3 from a 7 calculated from a 3+4? The answer is YES, there is a difference, an important difference.

The Gleason score is an central prognostic tool for clinicians when deciding what treatments are appropriate. Studies have shown that short-term outcomes for prostate cancer differ according to Gleason scores. Now, researchers at Brigham and Women’s Hospital (BWH), in Boston Ma, have shown that Gleason score is a strong predictor of prostate cancer mortality and that mortality rates differ among patients with a Gleason score of seven depending on whether Gleason pattern four is primary or secondary. This research is published in the May 11 issue of Journal of Clinical Oncology.

Tissue samples from prostatectomies and biopsies from men who were diagnosed with prostate cancer between 1984 and 2004 and were enrolled in the Physicians’ Health Study and Health Professionals Follow-up Study. The samples were then assigned primary and secondary Gleason patterns by pathologists. Researchers found that within the group of men with Gleason scores of seven, men with primary and secondary patterns of 4 and 3 respectively had worse long-term outcomes compared to men with a primary pattern of 3 and secondary pattern of 4.

“Four plus three cancers were associated with a three-fold increase in lethal prostate cancer compared to three plus four cancers,” said Jennifer Rider Stark, Post-doctoral research fellow at BWH and the Harvard School of Public Health. “If we are lumping these cancers into one category of Gleason score 7, then we are missing important prognostic information.”

For the purposes of this study lethal prostate cancer was defined by the development of bony metastases or prostate cancer death. Current clinical practice evaluates and treats men with three plus four cancer differently than a man with four plus three cancer, but until now there was no long-term mortality data to support this practice. Clinicians were making these decisions based primarily on surrogate outcomes such as prostate-specific antigen relapse.

“This study provides clinicians with further evidence that men who have Gleason scores of seven should be evaluated based on the predominant Gleason pattern,” Stark said.

This research was funded by grants from the National Cancer Institute.

So pay attention to how your Gleason score is devised. Men with Gleason 7 scores must be aware that all “7’s” are not the same. If your first number is a 4 your risk for developing bone metastases and dieing from your cancer is significantly higher then those with Gleason “7’s” where the first number is a 3.

Joel T Nowak MA, MSW