To provide a pharmaceutical composition which is effective on the treatments of estrogen-dependent tumors.

This pharmaceutical composition comprises a pharmaceutically acceptable carrier or diluent and a compound which contains a ring system and a sulfamate group of the formula [R1 and R2 are each independently selected from H, an alkyl, an alkenyl, a cycloalkyl, or an aryl, provided that at least one of R1 and R2 is H; the compound is an inhibitor of an enzyme (E.C.3.1.6.2) having a steroid sulfatase activity; and if the sulfamate group of the compound is replaced with a sulfate group to form a sulfate compound and incubated with a steroid sulfatase enzyme (E.C.3.1.6.2) at a pH 7.4 and 37°C, it provides a Km value of less than 50 μM.