Table 4.

Gastric and esophageal cancer biomarker testing methods and algorithms (HER2)

Characteristic, n = 54	No. %
Methods* and multimethod algorithms†
Concurrent HER2 FISH and IHC	22 (41)
HER2 IHC, reflex test‡ to FISH	21 (39)
Reflex test when result = IHC2+	6 (29)
Reflex test when result = IHC0, 1+ and 2+	6 (29)
Reflex test when result = IHC1+ and 2+	3 (14)
Reflex test when result = IHC2+ and 3+	3 (14)
Reflex test when result = IHC0, 1+, 2+, and 3+	2 (9)
Reflex test when result = IHC0 and 2+	1 (5)
HER2 FISH	7 (13)
Concurrent HER2 CISH and FISH	1 (2)
Concurrent HER2 CISH and IHC	1 (2)
Concurrent HER2 IHC and SISH	1 (2)
HER2 SISH	1 (2)

* Method, type of technology for testing a biomarker. Italicized choices represent various algorithms for reflexing to FISH test based on IHC results (0, 1+, 2+ and/or 3+). CISH = chromogenic in situ hybridization; FISH = fluorescence in situ hybridization; HER2 = human epidermal growth factor receptor 2; IHC = immunohistochemistry; SISH = silver in situ hybridization.

^† Multimethod algorithm, a sequence of methods for testing one biomarker, when multiple methods are used.

^‡ Reflex testing, confirming equivocal or borderline results by another method.