Patients with low H3K79me3 or DOT1L mRNA levels show poorer overall survival. a, b In total, 156 rectal cancer patient biopsy samples from treatment naïve patients were analyzed by immunohistochemistry for H3K79me3. Based on the staining intensity, the nuclei were given the relative score of 0 to 3, with 3 corresponding to highest staining intensity. Moreover, the overall percentage of the stained nuclei corresponding to each score was estimated for each analyzed sample. a Patient tissue samples were then classified based on the staining intensity and overall percentage of the stained nuclei as no staining, or low (5% of the nuclei with low score), medium/heterogeneous (50% of the nuclei stained heterogeneously), or high (100% of the nuclei with high score) staining. Solid arrows indicate positive, gray arrows weak, and white arrows negative staining. b The Kaplan-Meier survival plot for groups of patients with tissue samples classified as “High” (red line) and “Low or Heterogeneous” (blue line; comprising patients with no, low or heterogeneous staining) (p value, 0.051). c Separation of rectal adenocarcinoma patients from The Cancer Genome Atlas into “high” (n = 67) and “low” (n = 92) DOT1L mRNA expression (greater than or less than 4.7 reads per kilobase per million, respectively) displayed in the Kaplan-Meier survival plot revealed better overall survival (p value, 0.018) in patients with higher levels of DOT1L expression