Metastatic breast cancer with PLD as a new option for anthracycline-treated patients. The meta-analysis conducted by AI-Batran et al. in Germany included 935 patients from four studies, 274 of whom were treated with polyethylene glycol liposomal doxorubicin after multiple anthracycline treatments. The results confirmed that PLD resulted in improved clinical benefit rates in these anthracycline-treated patients; the only independent predictor of CBR was a good Eastern Clinical Oncology Collaborative Group physical status score; however, CBR was independent of factors including whether the patient was anthracycline-resistant, background of prior anthracycline therapy as adjuvant, salvage, or both, cumulative anthracycline dose, and the end of anthracycline therapy to the start of PLD time. An additional option for metastatic breast cancer: adjuvant chemotherapy after breast cancer surgery is now usually applied with anthracycline- and paclitaxel-containing regimens, so treatment after metastatic recurrence has gradually transitioned to regimens based on capecitabine, vincristine, gemcitabine and cisplatin. This study observed that polyethylene glycol liposomal doxorubicin could still achieve a clinical benefit of 32.2% in recurrent metastatic breast cancer with previous anthracyclines, which may be related to its special structure, where the liposomes attached a polyethylene glycol fragment and then wrapped doxorubicin, which could increase the stability of the drug, reduce the recognition and clearance by the mononuclear macrophage system, prolong the drug circulation time and half-life, and increase the local concentration in the tumor. Although this trial concluded that its cumulative dose is not related to anthracyclines, it should also be used with caution in clinical applications, considering that it has a cumulative dose problem itself, which is usually 663.9 mg/m2.