The mTOR effectors 4EBP1 and S6K2 are frequently coexpressed, and associated with a poor prognosis and endocrine resistance in breast cancer: a retrospective study including patients from the randomised Stockholm tamoxifen trials

Table 1 Association between high S6K2 and/or 4EBP1 mRNA and clinicopathological parameters in the four cohorts

S6K2 and/or 4EBP1 mRNA (Spearman R, Pvalue)
	Stockholm 2	Van de Vijver	Uppsala	Karolinska
	(n = 93)	(n = 295)	(n = 251)	(n = 159)
Lymph node status	R = -0.11	R = 0.07	R = 0.31	R = -0.07
Lymph node status	P = 0.25	P = 0.21	P = 0.000001	P = 0.36
Tumour size	R = -0.12	N/A	R = 0.32	R = 0.16
Tumour size	P = 0.23		P < 0.0000001	P = 0.040
Grade/proliferation^a	R = 0.23	R = 0.42	R = 0.45	R = 0.41
Grade/proliferation^a	P = 0.034	P < 0.0000001	P <0.0000001	P = <0.0000001
ER status	R = -0.01	R = -0.31	R = -0.26	R = -0.11
ER status	P = 0.91	P <0.0000001	P = 0.000046	P = 0.15
PgR status (protein)	N/A	N/A	R = -0.27	N/A
PgR status (protein)	N/A	N/A	P = 0.000010	N/A
PgR mRNA	N/A	R = -0.29,	R = -0.30	R = -0.16
PgR mRNA	N/A	P <0.0000001	P = 0.000002	P = 0.048

Spearman’s rank-order correlation evaluating the association between high S6K2 and/or 4EBP1 mRNA and clinicopathological parameters in the four cohorts. The variable S6K2 and/or 4EBP1 was defined in three groups as highest quartile mRNA expression of: neither S6K2 nor 4EBP1 (=0), either S6K2 or 4EBP1 (=1), or S6K2 and 4EBP1 (=2). 4EBP1, 4E-binding protein 1; ER, oestrogen receptor alpha; PgR, progesterone receptor; S6K2, p70 ribosomal S6 kinase 2.
^aStockholm 2, S-phase fraction; van de Vijver, cyclin A₂ mRNA expression; Uppsala and Karolinska, Elston grade. N/A, not available.

ISSN: 1465-542X