For women with hormone receptor-positive advanced breast cancer, endocrine 
therapies, including the selective estrogen receptor modulator tamoxifen, the 
aromatase inhibitors anastrozole, letrozole, and exemestane, and the selective 
estrogen receptor degrader fulvestrant, are recommended in clinical guidelines. 
The addition of targeted agents such as everolimus or palbociclib to aromatase 
inhibitors are also recommended as treatment options. Chemotherapy remains an 
option, although clinical guidelines have recommended these agents be reserved 
for patients with immediately life-threatening disease or if resistance to 
endocrine therapy is known or suspected. The present review has consolidated the 
tolerability profiles of the agents approved for use in the treatment of hormone 
receptor-positive advanced or metastatic breast cancer based on phase III 
registration trial data. Endocrine therapies are generally well tolerated, 
although the addition of targeted therapies to aromatase inhibitors or 
fulvestrant appears to increase the proportion of patients experiencing adverse 
events, and palbociclib and chemotherapy appear to be more closely associated 
with serious adverse events, including neutropenia.