Table 1.

Differences of average positive rate of IGκC RNA in situ hybridization in different groups

	n	Average positive rate of IGKC RNA in situ hybridization	χ2	P
Normal breast tissue	43	9.30% (4/43)a	173.317	.000
Breast cystic hyperplasia	46	8.70% (4/46)
Ductal carcinoma in situ	54	27.78% (15/54)b
Primary breast cancer	142	83.10% (118/142)
Lymph‐node metastatic breast cancer	39	97.87% (46/47)c

^aComparison of ductal carcinoma in situ vs normal breast tissue, χ² = 8.791, P = .003.

^bComparison of primary breast cancer vs ductal carcinoma in situ, χ² = 54.894, P = .000.

^cComparison of lymph‐node metastatic breast cancer vs primary breast cancer, χ² = 6.715, P = .010.