Background/Objectives: Cytochrome 1B1 (CYP1B1) is overexpressed in several cancers, contributing to carcinogenesis, cancer progression, and chemoresistance. Despite its known oncogenic role, its expression in bone sarcomas remains unknown. Methods: This study assessed CYP1B1 expression in osteosarcoma and chondrosarcoma using immunohistochemistry on tissue microarrays and analyzed corresponding transcriptomic profiles from public RNA-seq datasets. Associations with clinicopathological features, survival, drug sensitivity, and protein–protein interaction networks were also investigated. Results: CYP1B1 was overexpressed in 72.3% of bone sarcomas (78% of osteosarcomas and 82.1% of chondrosarcomas) and was significantly underexpressed in normal bone (12.5%, p < 0.001). Importantly, high CYP1B1 expression was found in younger patients (≤34 years; p = 0.013), but no other associations with tumor grade, size, or metastasis were observed. The mean survival rate of CYP1B1-positive patients was insignificantly shorter than that of negative patients (58.8 vs. 62.8 months; p = 0.170). Although not confirmed in the multivariate analysis, CYP1B1-positive patients had poorer survival in the univariate analysis, which may reflect tumor aggressiveness rather than prognostic value. Transcriptomic data showed significantly lower CYP1B1 mRNA in osteosarcoma versus normal bone, suggesting post-transcriptional or translational regulation. Drug sensitivity analysis revealed both positive and negative correlations between CYP1B1 expression and response to various compounds in the GDSC dataset, highlighting potential therapeutic implications. Conclusions: Despite low mRNA levels, CYP1B1 protein is consistently and selectively overexpressed in bone sarcomas, particularly in younger patients. While not prognostic, its expression profile warrants further investigation and evaluation as a therapeutic target or diagnostic biomarker, especially in refractory or advanced cases.

Background: Cytochrome P450 2J2 (CYP2J2) has been implicated in tumor biology, but its expression pattern and clinical significance in prostate and renal cancers remain poorly characterized. Methods: Commercially available tissue microarrays containing 208 renal and 121 prostate tissue specimens were used for immunohistochemical (IHC) characterization of CYP2J2 protein expression. We performed transcriptomic analysis and examined correlations with clinicopathological features and survival using the OncoDB 2.0 platform. Results: CYP2J2 immunoreactivity was mainly cytoplasmic, with minimal protein expression in both cancers. We identified positive staining in 7/100 (7.0%) prostate adenocarcinomas and 2/192 (1.0%) clear cell renal cell carcinoma (ccRCC) specimens, with negative expression in corresponding normal tissues. We detected no significant associations between protein expression and clinicopathological features in either cohort (all p > 0.05). In contrast, transcriptomic analysis revealed elevated CYP2J2 mRNA expression in both malignancies, with a slight increase in prostate adenocarcinoma (log₂ fold change = 1.10) and marked overexpression in ccRCC (log₂ fold change = 5.24) compared with normal tissues. We observed significant associations between CYP2J2 mRNA expression and pathological T stage in prostate adenocarcinoma (p = 0.0019) and pathological M stage in ccRCC (p = 0.0079). Moreover, higher CYP2J2 mRNA expression was associated with longer overall survival in ccRCC (HR = 0.64, 95% CI: 0.47–0.86; log-rank p = 0.0029) but not in prostate adenocarcinoma; however, these findings remain exploratory and do not establish independent prognostic value. Conclusions: Despite elevated transcript expression, CYP2J2 protein expression was infrequent in prostate adenocarcinoma and ccRCC, suggesting limited clinicopathological relevance and warranting further investigation using functional techniques.