CASCADE study: pronounced decline in treatment efficacy through the metastatic life of breast cancer patients

Abstract

Background: There is scarce information regarding the actual clinical benefit current therapies have on the general population and per tumour immunotype in advanced and/or metastatic breast cancer (LA/MBC). In this regard, analysis of the response elicited per line of treatment by a given pharmacological strategy will better guide the decision-making process, thus prioritizing most active drugs in earlier lines where they might have more chances of securing a long-lasting survival impact. Methods: 13 Spanish public hospitals serving nearly 5'000'000 inhabitants (>10% of the national population) were selected. 443 patients diagnosed of LA/MBC from 01/ 2007 to 12/2008 were followed until death, lost to follow-up, or until December 2013. Objective response rates (ORR) and clinical benefit rates (CBR) were analysed throughout all treatment lines and per tumour immunotype. Data collected included demographical, pathological, diagnostic, and therapeutic information for each line of treatment during this time. Descriptive statistics were applied (Methods have been previously described in ESMO Congress 2015 Poster no. 1882). Results: Important differences in both efficacy variables were seen according to treatment line and tumour immunotype. First line ORR and CBR were similar in all groups. As of the third line, however, objective responses in Triple-negative were minimal while still averaging 20% (range: 10.6% - 29.6%) for all other tumour types. HER2+ subgroups showed the overall greatest and most sustained responses (Table 1). Conclusions: There is a rapid and progressive reduction of treatment efficacy in LA/ MBC, especially in those patients who do not have or have lost the benefits of hormone and anti-HER2 targeted therapies. Therefore, introduction of the most active agents should not be delayed until very late lines of treatment. (Table Presented).