ABSTRACT
<p><b>OBJECTIVE</b>To investigate ALK genomic rearrangements and expression in prostate cancer, and their clinical implications.</p><p><b>METHODS</b>Two hundred and eighty-one cases of prostate cancer were included. ALK gene rearrangements were assessed by FISH in all cases, and ALK protein expression was assessed by immunohistochemistry in 191 cases.</p><p><b>RESULTS</b>The ALK gene was truncated (mostly 5' deletion) in 18 of 281 (6.4%) cases. EML4-ALK fusion gene was not detected. Genomic rearrangement of ALK gene was not statistically associated with Gleason score, age, TNM or baseline PSA level (P > 0.05). In all 18 cases, there were nuclear expression of ALK protein; in 12 cases, the expression was seen in 5%-30% of the tumor cells, and in the remaining 6 cases, the expression was seen in < 5% of the tumor cells.</p><p><b>CONCLUSIONS</b>ALK gene rearrangements occurred in 6.4%, of prostate cancer, and these may not be associated with disease progressions. The ALK protein expresses in the nucleus. The EML4-ALK fusion gene was not found in prostate cancer.</p>