[Clinical evaluation of anti-cancer or targeted drugs and the optimal timing for changing therapeutics-breast cancer].

Anti-cancer drugs for breast cancer should be continued while they express clinical anti-cancer activity, provided that their side effects are tolerable. With that exception, bisphosphonates and denosumab for bone metastasis are well recognized. Anthracyclines may be categorized as an exception due to their determined maximum tolerable dose. The efficacy of trastuzumab beyond metastatic disease progression has been confirmed by prospective randomized clinical trials, and other drugs may have the same properties. The clinical evaluation of cancer therapeutics should be performed with clinical information, and the RECIST guideline can be flexibly adapted.