TP53 and urinary bladder small cell neuroendocrine carcinoma: Compared to NECC, non-silent mutation of TP53 was significantly more frequent in both SCLC (103 of 110 tumors [94%], P < .001, two-sided Fisher exact test) and SCCB (18 of 19 tumors [95%], P < .001, two-sided Fisher exact test).