Table 2.

ERBB2 and ERBB3 mutations in different stages of lobular neoplastic progression

Study		ERBB2 alteration frequency			ERBB3 alteration frequency			Notes
		Total %	Mut	Amp	Total %	Mut	Amp
In situ	Harrison et al. [27]	94.7%	13/19	6/19	21%	4/19	0/19	17 PLCIS; 2 FLCIS
	Shamir et al. [33]	50%	6/16	2/16	18.7%	3/16	0/16	10 PLCIS; 6 FLCIS; ERBB2 and/or ERBB3 alterations in 60% PLCIS and 50% FLCIS
Primary ILC	Zhu et al. [37]	17.6%	3/17	–	23.5%	4/17	–	PILC
	Rosa-Rosa et al. [36]	26%	7/27	1/27	–	–	–	PILC; association with nuclear grade 3
	Christgen et al. [41]	5%	5/106	–	–	–	–	Grade 3 but no association with solid or pleomorphic
	Cao et al. [42]	19%	–	13/70	–	–	–	Amplification; no mutation assessment
	Deniziaut et al. [43]	15%	6/55	–	0%	0/55	–	Grade 3; positive association with solid presentation
	Ping et al. [44]	6%	6/100	–	–	–	–	CDH1 altered with ERBB2 mutation correlates with poor prognosis
	Lien et al. [31]	52.2%	5/24	8/24	–	–	–	PILC; 2% in classic ILC
mILC	Ma et al. [45]	7.8%	4/51	–	–	–	–	Metastatic ILC; confirmed neratinib efficacy in ERBB2 mutants in phase II trial; detection in ctDNA
	Ross et al. [46]	22.7%	4/22	1/22				Relapsed ILC; ERBB2 mutation enriched in CDH1 mutant tumours; I gene fusion not tabulated (ERBB2–GRB7)

CILC classic ILC, ctDNA circulating tumour DNA, FLCIS florid LCIS, mILC metastatic ILC, PILC pleomorphic ILC, PLCIS pleomorphic LCIS