In men who have prostate cancer (PCa) with lymph node (LN) involvement, very small tumor size is associated with a higher risk of cancer-specific death compared with men who have some larger tumors, new findings suggest.

Using the Surveillance, Epidemiology and End Results (SEER) database, researchers led by Paul L. Nguyen, MD, of the Dana-Farber Cancer Institute and Brigham and Women’s Hospital in Boston, identified 37,501 patients who underwent radical prostatectomy for PCa from 1988 to 2001. They stratified patients according to tumor size (microscopic focus only or 1 mm; 2–15 mm; 16–30 mm; larger than 30 mm) and regional LN involvement.

Among the 36,561 patients without LN involvement, the 10-year prostate cancer-specific mortality (PCSM) rate increased with increasing tumor size, the investigators reported online ahead of print in BJU International. Among the 940 men with LN involvement, however, those with the smallest tumors had a significantly increased 10-year PCSM rate compared with men who had 2–15 mm tumors (24.7% vs. 11.8%) and 16–30 mm tumors (24.7% vs. 15.5%). In adjusted analyses, these differences translated into a 2.8-fold and 3.1-fold increased risk of 10-year PCSM, respectively, for the patients with the smallest tumors. The latter group had a 10-year PCSM rate similar to that of men with tumors larger than 30 mm (24.7% vs. 24.9%).

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The authors concluded very small tumors in men with LN involvement might be especially aggressive, beyond what is captured by pathologic assessment of tumor grade and stage.