The PIK3CA/CEN3 probe is located on chromosome 3. A 680 Kb probe covering the PIK3CA gene region at 3q26.33 is labeled with an orange dye, and part of chromosome 3 (CEN3) is labeled with a green dye.

Gene amplification occurs at a higher frequency in lung squamous cell carcinoma patients. There is a significant difference in EGFR mutation rates compared to those without amplification. Prognosis is worse.