The invention provides a compound of formula (I) or a pharmaceutically acceptable ester, amide, solvate or salt thereof, including a salt of such an ester or amide, and a solvate of such an ester, amide or salt, wherein W, X, Y, Z, R
1
, R
2
, R
7
, R
8
, R
9
, R
10
, R
11
, R
12
, R
13
, R
14
, R
15
and R
16
are as defined in the specification. The invention also provides also provides the use of such compounds in the treatment or prophylaxis of a condition associated with a disease or disorder associated with estrogen receptor activity.