AJCC Pathologic Staging of Breast Cancer, 8th Edition, 2018

Pathologic staging of breast cancer involves testing surgically removed breast tissue and lymph nodes to determine where the cancer has grown, its size, and whether it has spread to other sites. Clarifying cancer staging can help doctors decide on the best treatment options and predict a patient’s treatment prognosis.

Pathologic staging is based on anatomic (T,N,M) staging in combination with tumor cell grading, human epidermal growth factor receptor 2 (HER2), estrogen receptor (ER), and progesterone receptor (PR) status.

Tumor (T): size and location of the primary tumor lesion; lymph nodes (N): whether the tumor has spread to the lymph nodes and, if so, the location and number of spread; metastatic lesions (M): whether the tumor has metastasized to other parts of the body and, if so, the location and number of metastases; and breast cancer cell grading (G): the degree of tumor cell differentiation; the higher the number, the less differentiated.

The following table shows the specifics of pathologic staging of breast cancer:

TNM	Grading	Human epidermal growth factor receptor-2 (HER-2)	Estrogen receptor (ER)	Progesterone receptor (PR)	Staging
Tis N0 M0	Any	Any	any	any	0
T1* N0 M0; T0 N1mi M0; T1* N1mi M0	G1	Positive	Positive	Positive	IA
				Negative
			Negative	Positive
				Negative
		Negative	Positive	Positive
				Negative
			Negative	Positive
				Negative
	G2	positive	Positive	Positive
				Negative
			Negative	Positive
				Negative
		Negative	Positive	Positive
				Negative
			Negative	Positive
				Negative	IB
	G3	positive	Positive	Positive	IA
				Negative
			Negative	Positive
				Negative
		Negative	Positive	Positive
				Negative
			Negative	Positive
				Negative	IB

T0  N1** M0; T1  N1** M0; T2  N0 M0	G1	Positive	Positive	Positive	IA
				Negative	IB
			Negative	Positive
				Negative	IIA
		Negative	Positive	Positive	IA
				Negative	IB
			Negative	Positive
				Negative	IIA
	G2	positive	Positive	Positive	IA
				Negative	IB
			Negative	Positive
				Negative	IIA
		Negative	Positive	Positive	IA
				Negative	IIA
			Negative	Positive
				Negative
	G3	positive	Positive	Positive	IA
				Negative	IIA
			Negative	Positive
				Negative
		Negative	Positive	Positive	IB
				Negative	IIA
			Negative	Positive
				Negative

T2  N1*** M0; T3  N0 M0	G1	positive	Positive	Positive	IA
				Negative	IIB
			Negative	Positive
				Negative
		Negative	Positive	Positive	IA
				Negative	IIB
			Negative	Positive
				Negative
	G2	positive	Positive	Positive	IB
				Negative	IIB
			Negative	Positive
				Negative
		Negative	Positive	Positive	IB
				Negative	IIB
			Negative	Positive
				Negative
	G3	positive	Positive	Positive	IB
				Negative	IIB
			Negative	Positive
				Negative
		Negative	Positive	Positive	IIA
				Negative	IIB
			Negative	Positive
				Negative	IIIA

T0  N2  M0; T1*  N2 M0; T2  N2 M0; T3  N1*** M0; T3  N2  M0	G1	positive	Positive	Positive	IB
				Negative	IIIA
			Negative	Positive
				Negative
		Negative	Positive	Positive	IB
				Negative	IIIA
			Negative	Positive
				Negative
	G2	positive	Positive	Positive	IB
				Negative	IIIA
			Negative	Positive
				Negative
		Negative	Positive	Positive	IB
				Negative	IIIA
			Negative	Positive
				Negative	IIIB
	G3	positive	Positive	Positive	IIA
				Negative	IIIA
			Negative	Positive
				Negative
		Negative	Positive	Positive	IIB
				Negative	IIIA
			Negative	Positive
				Negative	IIIC

T4  N0  M0; T4  N1*** M0; T4  N2 M0; Any T  N3  M0	G1	positive	Positive	Positive	IIIA
				Negative	IIIB
			Negative	Positive
				Negative
		Negative	Positive	Positive	IIIA
				Negative	IIIB
			Negative	Positive
				Negative
	G2	positive	Positive	Positive	IIIA
				Negative	IIIB
			Negative	Positive
				Negative
		Negative	Positive	Positive	IIIA
				Negative	IIIB
			Negative	Positive
				Negative	IIIC
	G3	positive	Positive	Positive	IIIB
				Negative
			Negative	Positive
				Negative
		Negative	Positive	Positive
				Negative	IIIC
			Negative	Positive
				Negative
Any T  Any N  M1	Any	any	any	any	IV

Notes:

*T1 includes T1mi.

**N1 excludes N1mi, and T1 N0 M0 breast cancer staging with the same prognostic factor status includes T1 N1mi M0 and T0 N1mi M0.

***N1 includes N1mi, and T2N1,T3N1,T4N1 include T2N1mi, T3N1mi, and T4N1mi, respectively.