361PCisplatin given at three divided doses for three consecutive days in metastatic breast cancer: An alternative schedule for one full dose with comparable efficacy but less CINV and hypomagnesaemia

Abstract Background Cisplatin, a common chemotherapeutic for metastatic breast cancer (MBC), is recommended to be applied at 75 mg/m2 every 3 weeks, but divided doses over several days are commonly used. Toxicity profile difference of these 2 dosing regimens is rarely reported, so we retrospectively compared toxicity of cisplatin at 75mg/m2 one day versus 25mg/m2 for 3 consecutive days repeated every three weeks focusing on nausea/vomiting, abnormalities of serum electrolytes and renal function. Methods Between December 2008 and May 2015, 227 patients underwent 1 day of cisplatin treatment with hydration and magnesium supplementation and 256 patients underwent 3 days of treatment without hydration and magnesium supplementation were retrospectively analyzed. The number of patients with first-line and second-line chemotherapy in 1 day plan group was 99 and 109, and in 3 days plan group was 128 and 147. Results The objective response rate (ORR), progression-free survival (PFS) and overall survival (OS) were similar between the two groups. Grade 1–4 nausea/vomiting differed significantly between the 1-day and 3-day regimen (161[70.9%] vs. 132[51.6%], p  Conclusions In conclusion, toxicity profile of two dosing regimen of cisplatin is different. When cisplatin is given clinically at 75 mg/m2 once every three weeks, more attention should be paid to controlling nausea/vomiting better and strengthening the supplementation of magnesium. Legal entity responsible for the study The authors. Funding Has not received any funding. Disclosure All authors have declared no conflicts of interest.