The Influence of a Gene-Expression Signature on the Treatment of Diagnostically Challenging Melanocytic Lesions

Figures & data

Table 1.  Demographic and other baseline characteristics.

Characteristic	Statistic/category	All patients (n = 315)^†	Diagnostically challenging subset (n = 77)
Age (years)	n	315	77
	Mean	49.0	43.9
	SD	18.85	17.32
	Median	51	44
	Min, max	2, 94	5, 81
Gender	Female	166 (52.7%)	42 (54.5%)
	Male	149 (47.3%)	35 (45.5%)
Procedure type	Shave biopsy	274 (87.0%)	72 (93.5%)
	Elliptical excision	23 (7.3%)	3 (3.9%)
	Punch biopsy	17 (5.4%)	1 (1.3%)
	Missing	1 (0.3%)	1 (1.3%)
Anatomical site of lesion	Back/neck	111 (35.2%)	24 (31.2%)
	Extremities	81 (25.7%)	18 (23.4%)
	Abdomen	28 (8.9%)	14 (18.2%)
	Chest	23 (7.3%)	7 (9.1%)
	Face	14 (4.4%)	1 (1.3%)
	Acral	8 (2.5%)	1 (1.3%)
	Scalp	5 (1.6%)	2 (2.6%)
	Other	45 (14.3%)	10 (13.0%)
Pre-test diagnosis	Benign	137 (43.5%)	0
	Malignant	101 (32.1%)	0
	Indeterminate	77 (24.4%)	77 (100.0%)
Gene signature score	N	315	77
	Mean	-3.5	-5.3
	SD	5.37	4.68
	Median	-3.6	-5.2
	Min, max	-16.3, 8.4	-15.6, 4.0
Gene signature result	Benign	214 (67.9%)^‡	64 (83.1%)^‡
	Malignant	92 (29.2%)	13 (16.9%)
	Indeterminate	9 (2.9%)^§	0

^†68/315 (21.6%) patients were tested after the introduction of the indeterminate zone.

^‡Scores between -2.0 and -0.1 were produced by 33 cases prior to the introduction of the indeterminate reporting range, seven of which were in the ‘diagnostically challenging’ subset, and were reported as benign.

^§The small proportion of ‘indeterminate’ test results reflects the incorporation of the indeterminate reporting range during the course of the clinical experience program.

Max: Maximum; Min: Minimum; SD: Standard deviation.

Table 2.  Change between most invasive pre-test treatment recommendations and actual treatment.

Overall change in treatment	All patients (n = 315)		Diagnostically challenging subset (n = 77)
	Fraction	Percentage	Fraction	Percentage
All test results	201/315	63.8	55/77	71.4
Benign test result	136/214	63.6	44/64	68.8
Malignant test result	58/92	63.0	11/13	84.6
Indeterminate test result	7/9	77.8	0	–
Upgrades and downgrades for those who made a change in treatment
All test results^†
Upgrade	93/167	55.7	16/52	30.8
Downgrade	74/167	44.3	36/52	69.2
Benign test result^‡
Upgrade	60/125	48.0	10/43	23.3
Downgrade	65/125	52.0	33/43	76.7
Malignant test result^§
Upgrade	28/37	75.7	6/9	66.7
Downgrade	9/37	24.3	3/9	33.3

^†30 cases were excluded due to selection of ‘other’ under ‘treatment recommendations’ (two in the diagnostically challenging subset) and four cases were lost to follow-up during the course of the study (one in the diagnostically challenging subset).

^‡For benign test results, seven cases were excluded due to selection of ‘other’ under ‘treatment recommendations’ and four cases were lost to follow-up (one in the diagnostically challenging subset).

^§For malignant test results, 21 cases were excluded due to selection of ‘other’ under ‘treatment recommendations’ (two in the diagnostically challenging subset).

Table 3.  Treatment decisions among cases with changes from pre-test recommendations to actual treatment.

All patients^† (n = 201)		Test result
		Benign (n = 136)	Malignant (n = 58)	Total (n = 201)
Pretest treatment recommendation by dermatopathologist	Re-excision	87 (64.0%)	50 (86.2%)	139 (69.2%)
	No re-excision	49 (36.0%)	8 (13.8%)	62 (30.8%)
Actual treatment by dermatologist	Re-excision	42 (30.9%)	27 (46.6%)	71 (35.3%)
	No re-excision	83 (61.0%)	10 (17.2%)	96 (47.8%)
	Other	7 (5.1%)	21 (36.2%)	30 (14.9%)
	Lost to follow-up	4 (2.9%)	0	4 (2.0%)
Diagnostically challenging subset (n = 55)		Benign (n = 44)	Malignant (n = 11)	Total (n = 55)
Pretest treatment recommendation by dermatopathologist	Re-excision	41 (93.2%)	11 (100%)	52 (94.5%)
	No re-excision	3 (6.8%)	0	3 (5.5%)
Actual treatment by dermatologist	Re-excision	9 (20.5%)	6 (54.5%)	15 (27.3%)
	No re-excision	34 (77.3%)	3 (27.3%)	37 (67.3%)
	Other	0	2 (18.2%)	2 (3.6%)
	Lost to follow-up	1 (2.3%)	0	1 (1.8%)

^†Seven lesions with indeterminate test results are only included in total column. None of these lesions were in the diagnostically challenging subset.