Tumour content ratio matters for detecting epidermal growth factor receptor mutation by cobas test in small biopsies; a retrospective study

Table 1 Patient characteristics

	All patients n = 132
Age, year, median (IQR)	69 (61–76)
Male, n (%)	49 (37)
EGFR mutation with PCR clamp, n (%)
19del	65 (49)
L858R	57 (43)
L861Q	4 (3)
G719X	5 (5)
T790 M	1 (1)
Smoking Status, n (%)
Never	84 (64)
Former/Current	48 (36)
Tumour histological type, n (%)
Adenocarcinoma	128 (97)
Squamous cell carcinoma	3 (2)
NSCLC with morphological squamous cell and adenocarcinoma patterns	1 (1)
Stage, n (%)
1	19 (14)
2	8 (6)
3A	8 (6)
3B	7 (5)
4	90 (68)
TKI therapy, n (%)	110 (83)
Gefitinib^a	64 (58)
Erlotinib^a	23 (21)
Afatinib^a	22 (20)
Naquotinib^a	1 (1)
Number of chemotherapies before TKI therapy, n (%) ^a
0 regimen	65 (59)
1 regimen	37 (34)
2 regimens	6 (5)
3 regimens	2 (2)
Response to TKI, n (%)^a
PR/CR	81 (73)
SD	12 (11)
PD	11 (10)
NA	6 (5)
PFS for the first TKI therapy, m, median (95%CI)	12.2 (9.7–13.7)
Tumour content ratio^b, %, median (IQR)	17 (10–31)

Abbreviations: IQR interquartile range, EGFR epidermal growth factor receptor, NSCLC non-small cell carcinoma, TKI tyrosine kinase inhibitors, PR partial response, CR Complete Response, SD Stable Disease, PD Progressive Disease, NA not available, PFS progression free survival
^aAnalysis of 110 patients who received TKI therapy. 23 of the patients showed negative results with the cobas method
^bTumour cell count over the total cell count conducted on a slide-mounted biopsy sample

ISSN: 1471-2407