For the three different regions within the luminal layer, the percentage of HER2-positive tumor cells was higher in the lateral (anal and oral) regions than in the central region, although this did not reach statistical significance [median percentage of HER2-positive cells in the luminal anal region of 58.3 % (range 4.3–92.2 %) vs 65.0 % (range 4.2–99.7 %) for the luminal oral region and 57.2 % (range 0.0–95.0 %) for the luminal central region; p = 0.98]. The gene discussed is ERBB2; the disease is neoplasm.