CCND1 and cancer: After conducting a comprehensive analysis of CCND1 mRNA expression using three different databases (GEPIA, UALCAN, and TIMER), as well as a survival analysis using the GEPIA and Kaplan-Meier plotter databases, the results showed that CCND1 expression was significantly upregulated in six cancer types (HNSC, KIRC, PAAD, STAD, THCA, and UCEC).