TABLE 1.

Comparison of HER2 alteration testing methods and recommendation level in NSCLC

Methods	Alterations	Types of alteration	Sample type	Sensitivity	Specificity	TAT	Advantages and disadvantages	Recommendation level
Sanger	Point mutation, small insertions/deletions	Known/unknown alterations	FFPE cytology	Moderate	Moderate	4–5 days	High requirement for sample input and low testing throughput	Recommended
qRT‐PCR	Point mutation, small insertions/deletions, amplification	Known alterations	FFPE cytology liquid	High	High	2–3 days	Widely used platform, relatively fast turnaround time, but unable to detect unknown alterations	Recommended
FISH	Amplification	Known/unknown alterations	FFPE cytology	Moderate	Moderate	2–3 days	Intuitive results, high requirement for sample quality, complicated testing and analysis procedures	Recommended
IHC	Overexpression	Protein level	FFPE	Moderate	Moderate	1–2 days	Cheap, fast, and highly accessible platform, but poor antibody accessibility and risk of false negatives and false positives	Recommended
NGS	Point mutation, small insertions/deletions, fusion, amplification	Known/unknown alterations, dependent on panel coverage	FFPE cytology liquid	High	High	5–7 days	High throughput, cover multiple alteration types, high sensitivity and specificity, but highly dependent on probe design and bioinformatic analysis	Strongly recommended

Abbreviations: HER2, human epidermal growth factor receptor 2; FFPE, formalin‐fixed paraffin‐embedded; FISH, fluorescence in situ hybridization; IHC, immunohistochemistry; NGS, next‐generation sequencing; NSCLC, non–small cell lung cancer; qRT‐PCR, quantitative real time PCR; TAT, turnaround time.