Nearly 20% of men with metastatic, castration-resistant prostate cancer had tumors that developed into the treatment-emergent small-cell neuroendocrine (t-SCNC) subtype, which is associated with shorter survival than other subtypes, according to findings from a study published in the Journal of Clinical Oncology.

As drug-resistant prostate cancer progresses, it can sometimes transition to a different subtype. Using samples from 160 men originally diagnosed with adenocarcinoma prostate cancer that had progressed, researchers analyzed metastatic tumors in the bone, lymph nodes, liver, or other soft tissues. They found that in 27 (17%) of the cases, the tumor had developed into the t-SCNC subtype. Twenty of those samples had only the t-SCNC subtype, whereas seven had both adenocarcinoma and t-SCNC subtypes.

Additionally, the researchers developed a gene signature for t-SCNC that correctly distinguished those tumors from adenocarcinoma in a different set of tumor samples. The researchers said that the validated gene signature might help future research identify targeted cancer treatments for t-SCNC’s unique molecular characteristics.