Effects of a controlled-release cisplatin delivery system used after resection of mammary carcinoma in mice

Objective-To evaluate efficacy of a controlled-release cisplatin delivery s ystem, used after marginal resection of mammary carcinoma (ie, resection of grossly evident tumor) in mice, to prevent tumor regrowth and metastasis. Animals-42 female C3H-HeJ mice. Procedure-Mice were inoculated with mammary carcinoma cells. Between 2 and 6 days later, tumors were marginally resected and mice were assigned to 1 o f 3 groups: no treatment (control; n = 14), cisplatin administered intraper itoneally (IP cisplatin; 14), and cisplatin delivered by use of an open-cel l polylactic acid system placed within the tumor bed (slow-release cisplati n; 14). Tumor regrowth was measured daily. Mice were euthanatized 14 days a fter surgery, and complete necropsies were performed. Results-Tumor regrowth was not detected in the slow-release cisplatin group ; however, tumor regrowth was detected in 7 of 14 mice in the IP cisplatin group and 14 of 14 mice in the control group, Median (+/- SD) number of day s to tumor regrowth was 13.5 +/- 0.64 and 7.79 +/- 0.87 in the IP cisplatin and control groups, respectively. Mice in the IP cisplatin group had signi ficantly delayed tumor regrowth, compared with control mice. Metastases to lungs were detected in 8 of 14 control mice but were not detected in mice i n either cisplatin treatment group. Conclusions and Clinical Relevance-The open-cell polylactic acid with cispl atin delivery system was successful in delaying local tumor regrowth and me tastasis in mice with marginally resected mammary carcinoma. Use of a contr olled-release cisplatin delivery system may be an effective adjunct treatme nt following excision of mammary carcinoma in humans and other animals.