Abstract P6-09-33: CASCADE study: Rapid survival decline per treatment line in metastatic breast cancer
Authors: García J , De La Haba J , Servitja S , Santaballa A , De Paz L , Plata Y , Garau I , Florián J , Chacón JI , García P , Zamora P , Orcajo L , Rodríguez-Villanueva J , San José B , Martínez E , Seguí MA 
Published: March 2017

BACKGROUND: Appraisal of the impact that current therapeutic strategies of advanced breast cancer (ABC) have on the survival expectancy, is vital to understand the prognosis of this disease. This entails assessing simultaneously the tumour phenotype and the therapeutic approach used per line of treatment. CASCADE is an epidemiological, retrospective, multicenter study aimed to retrieve demographic and clinical information from a representative cohort of ABC patients treated within the Spanish National Healthcare System.

MATERIAL AND METHODS: 13 Spanish public hospitals serving nearly 5M inhabitants (~10% of the national population) identified 422 ABC patients between 01/2007 and 12/2008 who received active treatment for their disease and were followed until death, lost to follow-up, or until December 2013. Overall Survival (OS) was analysed per tumour immunotype and treatment line from the diagnosis until a minimum of 10 patients were still evaluable. OS resulting from the different therapeutic approaches per line was also revised. Data collected included demographical, pathological, diagnostic, and therapeutic information for the entire follow-up. Descriptive statistics were applied (Methods previously described in SABCS 2015 Poster P3-07-39).

RESULTS: Remarkably, by the 2nd line of treatment, on average, one third of the OS is already gone. Tumour type imposes clear differences in this decline rate. As expected, triple-negative patients have the shortest survival expectancy at diagnosis, but their OS attrition rate is the slowest compared to the other subgroups (Table 1).

Table 1. OS per tumour type and line of treatment in ABC.PopulationOS from ABC Diagnosis (months)OS from 1L (months)OS from 2L (months)OS from 3L (months)OS from 4L (months)OS from 5L (months)Whole (N=422)33.532.622.616.613.513.3HER2-/HR+ (N=187)38.637.122.415.612.610.2Triple-negative (N=67)19.016.515.814.110.29.5HER2+/HR+ (N=72)34.433.729.421.620.318.9HER2+/HR- (N=53)36.335.423.113.19.314.1

OS time derived from the five mayor therapeutic approaches used at any given line, could only be registered for chemotherapy, hormone therapy and chemo + anti-HER2 therapy. Regardless of their treatment history, patients treated exclusively with hormone therapy portray a less aggressive behaviour than those treated with chemotherapy only, resembling the natural history of HER2-/HR+ and triple-negative phenotypes (Table 2).

Table 2. OS per pharmacological approach and line of treatment in ABC.Pharmacological treatmentOS from 1L (months)OS from 2L (months)OS from 3L (months)OS from 4L (months)OS from 5L (months)OS from 6L (months)OS from 7L (months)Chemotherapy (N=155)25.012.513.310.88.310.87.2Hormone therapy (N=92)44.030.922.311.214.0--Chemo + Anti-HER2 thp. (N=57)36.927.218.814.125.8--Chemo + Other Targeted thp. (N=44)19.721.014.121.1---Chemo + Hormone thp. (N=38)44.325.0-----Other Targeted thp.: anti-angiogenic antibody, mTOR inhibitor, anti-EGFR antibody, etc.

CONCLUSION: Chances to benefit from effective treatments may be jeopardized if their start is postponed to late lines. Only the most widely used therapies and, ultimately chemotherapy, hold until very late in the treatment of the advanced disease.

Citation Format: García J, De La Haba J, Servitja S, Santaballa A, De Paz L, Plata Y, Garau I, Florián J, Chacón JI, García P, Zamora P, Orcajo L, Rodríguez-Villanueva J, San José B, Martínez E, Seguí MA. CASCADE study: Rapid survival decline per treatment line in metastatic breast cancer [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr P6-09-33.