Table 1.

Association of B2M expression with the clinico- and histo-pathological features of patients with epithelial-type ovarian tumours

Clinicopathological features	n	B2M expression		P value
		Positive n (%)	Negative n (%)
Age at diagnosis
≤45	41	32 (78.05)	9 (21.95)	0.567
>45	67	49 (73.13)	18 (26.87)
Primary tumour size
≤2 cm	7	6 (85.71)	1 (14.29)	0.498
>2 cm	101	75 (74.26)	26 (25.74)
Benign tumour
Serous	16	12 (68.75)	4 (31.25)	0.326a
Mucinous	18	9 (88.24)	9 (11.76)
Endometrioid	4	2 (50.00)	2 50.00)
Borderline tumour
Serous	14	10 (71.43)	4 (28.57)	0.191b
Mucinous	21	19 (90.48)	2 (9.52)
Clear cell	1	1 (100)	0
Endometrioid	1	1 (100)	0
Transitional cell	1	1 (100)	0
Malignant tumour				>0.999c
Serous
High-grade	12	11 (91.67)	1 (8.33)	0.083d
Low-grade	6	3 (50.00)	3 (50.00)
Mucinous	5	4 (80.00)	1 (20.00)
Clear cell	7	5 (71.43)	2 (28.57)
Endometrioid	1	1 (100)	0
Transitional cell	1	1 (100)	0

The expression of B2M protein was detected by immunohistochemistry. For comparison of B2M expression associated with age, χ² test was applied. For comparison of B2M expression associated with primary tumour size, χ² test with continuity correction was applied. For multiple comparisons of B2M expression associated with the histopathological features, Fisher’s exact test was applied

n number of cases; Positive positive expression; Negative negative expression

^aMultiple comparisons of the histological types (serous, mucinous and endometrioid tumours) in benign tumors

^bComparison between serous and mucinous borderline tumours

^cMultiple comparisons of the histological types (serous, mucinous and clear cell tumours) in malignant tumors

^dComparison between low-grade serous tumour and high-grade serous tumour