The cable should be intended for balanced signals, so it should have three wires (plus, minus, ground).
It should be shielded, and the signal wires should be twisted to reduce interference.
A microphone cable is a good choice for these installations. However, the rubber surface of the cable can make it challenging to pull the cable in for example tubings inside the walls. When choosing a microphone cable, ensure that the cable is shielded to reduce interference.
There may be problems with 'instrument cables' that are often sold in electronics stores because the signal wires inside the cable are not twisted.
Cables suitable for line-level signals are typically 0.22 - 0.5 mm².
Genelec offers a cable designed for installations which can be obtained from Genelec dealers.