Incidental gallbladder cancer diagnosis confers survival advantage irrespective of tumour stage and characteristics

Table 1 Reasons for not proceeding with oncological resection, n (%)

Reason	IGBC (n = 33, 19%)	NIGBC (n = 138, 81%)	Total number (n = 171)1
Locally advanced inoperable disease	0	41 (30)	41 (24)
Metastatic disease	21 (64)	78 (56)	99 (58)
Patient declined surgery	5 (15)	3 (2)	8 (5)
Unfit for surgery	4 (12)	15 (11)	19 (11)
Surgery not required	3 (9)	0	3 (2)

¹Data missing for one patient.

Table 2 Patient and tumour characteristics for the surgical group, n (%)

Variable	IGBC (n = 58)	NIGBC (n = 32)	P value
Median age (range)	63 yr (55.8-71.3)	66 yr (66.0-71.5)	0.302
Gender			0.08
Male	9 (16)	10 (32)
Female	49 (84)	22 (68)
Ethnicity			0.507
Caucasian	39 (67)	23 (72)
Asian	15 (26)	5 (16)
Black	3 (5)	2 (6)
Missing	1 (2)	2 (6)
Median BMI (range)	28.2 (24.3-32.1)	28.2 (24.2-30.7)	0.563
ASA score			0.829
1	4 (7)	2 (6)
2	43 (74)	23 (72)
3	10 (17)	6 (19)
Missing	1 (2)	1 (3)
Median CCI (range)	4 (3-5)	4 (4-6)	0.635
Extent of surgery			< 0.001
Minor resection	57 (98)	24 (75)
Major resection	1 (2)	8 (25)
T stage			< 0.001
CIS	1 (2)	1 (3)
T1a	3 (5)	0
T1b	4 (7)	1 (3)
T2	42 (72)	12 (38)
T3	7 (12)	15 (47)
T4	1 (2)	3 (9)
N status			0.051
N0	41 (71)	16 (50)
N1/2	17 (29)	16 (50)
Histologic type			0.746
CIS	1 (2)	1 (3)
Adenocarcinoma	55 (94)	30 (94)
Adeno-squamous	1 (2)	1 (3)
Mixed	1 (2)	0
Degree of differentiation (CIS excluded)			0.614
Well	7 (12)	4 (13)
Moderate	30 (52)	20 (63)
Poor	12 (21)	5 (16)
Undifferentiated/unclassified	8 (14)	2 (6)
Resection margin			0.169
Negative	53 (91)	26 (81)
Positive	5 (9)	6 (19)
Cystic duct margin on index cholecystectomy	6 (10)	N/A	N/A
Post-operative complications	15 (26)	11 (34)	0.394
Pattern of recurrence			0.628
Local/regional	5 (9)	5 (16)
Distant	6 (10)	5 (16)
Local and distant	2 (3)	1 (3)
Adjuvant chemotherapy	12 (21)	8 (25)	0.502

ASA: American Society of Anesthesiology; CCI: Charlson Comorbidity Index; BMI: Body mass index.

Table 3 Types of surgeries performed in surgically treated patients of the study group, n (%)

Type of surgery	IGBC (n = 58)	NIGBC (n = 32)	Total number (n = 90)
Radical cholecystectomy	0	18 (56)	18 (20)
Radical cholecystectomy +extrahepatic bile duct excision	0	6 (19)	6 (7)
Gallbladder bed resection	36 (62)	0	36 (40)
Gallbladder bed resection + extrahepatic bile duct excision	17 (30)	0	17 (19)
Segment IVb + V liver resection	2 (3)	0	2 (2)
Extrahepatic bile duct excision	2 (3)	0	2 (2)
Extended resections:			4 (4)
Central hepatectomy + caudate lobe resection + extrahepatic bile duct excision	0	1 (3)	1 (1)
Pancreaticoduodenectomy + Gallbladder bed resection + right hemicolectomy	0	1 (3)
Pancreaticoduodenectomy + right hepatectomy	0	1 (3)
Radical cholecystectomy + right hemicolectomy + partial gastrectomy	0	1 (3)

Portal lymphadenectomy performed in all cases.

Table 4 Cox proportional hazard analysis for overall survival

Variable	P value	HR (95%CI)	P value	HR (95%CI)	P value	HR (95%CI)
	Univariable analysis		Multivariable analysis		Multivariable analysis (excluding timing of diagnosis variable)
Age	0.011	1.04 (1.01-1.07)	0.453	1.02 (0.97-1.08)	0.153	1.04 (0.99-1.10)
Gender	0.96	1.01 (0.71-1.44)	-	-	-	-
Race	0.853	1.05 (0.61-1.81)	-	-	-	-
BMI	0.601	0.983 (0.92-1.05)	-	-	-	-
ASA score	0.024	1.96 (1.09-3.52)	0.121	2.26 (0.81-6.31)	0.061	2.53 (0.96-6.66)
CCI score	0.064	1.19 (0.99-1.42)	0.66	0.91 (0.58-1.41)	0.269	0.78 (0.50-1.21)
T stage	< 0.001	2.73 (1.72-4.34)	0.913	1.04 (0.56-1.90)	0.088	1.62 (0.93-2.81)
N stage	< 0.001	5.65 (2.84-11.25)	< 0.001	3.07 (1.72-5.46)	0.001	3.59 (1.72-7.49)
R status	< 0.001	7.35 (3.38-15.95)	< 0.001	5.26 (2.10-13.13)	0.012	3.00 (1.27-7.07)
Post-operative complications	0.885	1.05 (0.53-2.09)	-	-	-	-
Non-incidental diagnosis	0.004	2.41 (1.32-4.38)	0.026	2.25 (1.10-4.58)	Not included in analysis	Not included in analysis
Degree of differentiation	0.443	1.40 (0.61-3.21)	-	-	-	-
Adjuvant chemotherapy	0.87	1.07 (0.47-2.44)	-	-	-	-

ASA: American Society of Anesthesiology; CCI: Charlson Comorbidity Index; BMI: Body mass index.

Table 5 Cox proportional hazard analysis for disease free survival

Variable	P value	HR (95%CI)	P value	HR (95%CI)	P value	HR (95%CI)
	Univariable analysis		Multivariable analysis		Multivariable analysis (excluding timing of diagnosis variable)
Age	0.275	1.02 (0.98-1.06)	-	-	-	-
Gender	0.732	0.85 (0.34-2.13)	-	-	-	-
Race	0.997	1.13 (0.15-8.51)	-	-	-	-
BMI	0.782	0.99 (0.91-1.07)	-	-	-	-
ASA score	0.817	0.91 (0.42-1.98)	-	-	-	-
CCI score	0.842	0.98 (0.76-1.26)	-	-	-	-
T stage	0.021	2.06 (1.12-3.82)	0.504	1.26 (0.64-2.47)	0.21	1.53 (0.79-2.97)
N stage	0.001	4.08 (1.83-9.08)	0.006	3.18 (1.39-7.26)	0.008	3.08 (1.35-7.06)
R status	< 0.001	11.05 (3.31-36.94)	0.006	5.76 (1.67-19.88)	0.002	6.95 (1.98-24.34)
Post-operative complications	0.404	0.63 (0.22-1.85)	-	-	-	-
Non-incidental diagnosis	0.011	2.78 (1.26-6.12)	0.09	2.13 (0.89-5.09)	Not included in analysis	Not included in analysis
Degree of differentiation	0.211	0.65 (0.33-1.28)	-	-	-	-
Adjuvant chemotherapy	0.457	1.42 (0.56-3.58)	-	-	-	-

ASA: American Society of Anesthesiology; CCI: Charlson Comorbidity Index; BMI: Body mass index.