This is a Phase I dose escalation study of cisplatin and concurrent radiation in patients with ER negative, PR negative and HER2 negative breast cancer who have undergone breast-conserving surgery or mastectomy. Primary objective: To assess the safety, tolerability, and maximum tolerated dose (MTD) of cisplatin when given concurrently with radiation therapy for participants with Stage II or III breast cancer who have undergone breast conserving surgery or mastectomy