Chest acne is treated in a similar manner as facial acne and the treatment options have be quite comprehensively discussed elsewhere in this forum which you can refer to. They include topicals, oral antibiotics and oral isotretinoin.
The main difference is that chest acne tends to respond more slowly than facial acne and may be more prone to cause thickened scar (acne keloids).
Also acne mimics such as Malassezia folliculitis need to be excluded.
Do consult your doctor for a clinical assessment and discussion on which medication is best suited for you based on the severity of your chest acne and previous response or non-response to medications given.