Yes, BREASTS is a Scrabble word!

Letter values in Scrabble US: B 3, R 1, E 1, A 1, S 1, T 1, S 1.

Is it a valid word?

BREASTS is a valid word in the official Scrabble dictionary (US), the UK Scrabble Dictionary and Words with Friends (ENABLE).

the front of the trunk from the neck to the abdomen
either of two soft fleshy milk-secreting glandular organs on the chest of a woman
meat carved from the breast of a fowl
the part of an animal's body that corresponds to a person's chest

Also: white meat.