Table 1

Breast cancer in the Million Women Study: percentages of unknown values for tumour grade, estrogen receptor status and nodal status among current users of estrogen therapy, current users of estrogen plus progestogen and never-users of hormone replacement therapy

	ET (n=2131)^*	E+P (n=4292)^*	No HRT (n=6127)^*
Known tumour grade (n)^†	978	1893	3096
Percentage unknown (%)	54.1	55.9	49.5
Known ER status (n)^†	753	1684	1585
Percentage unknown (%)	64.7	60.8	74.1
Known nodal status (n)^†	898	1781	2848
Percentage unknown (%)	57.9	58.5	53.5

↵* Derived from Figure 1 in Reference 24.
↵† Derived from Figure 3 in Reference 24.
E+P, estrogen plus progestogen; ER, estrogen receptor; ET, estrogen therapy; HRT, hormone replacement therapy.