The Factors Of The Relative Dose Intensity(RDI) And Its Effect On The Outcome Of Breast Cancer Patients

BackgroundThe current standard of care for breast cancer includes breast surgery,local radiation therapy,systemic adjuvant and neoadjuvant chemotherapy,endocrine therapy and target therapy.Chemotherapy has been shown to improve breast cancer survival.However,chemotherapy can also damage the normal tissue cells of the body when it killing tumor cells,resulting in serious adverse events.Relative dose intensity(RDI)is an indicator used most frequently to measure and monitor the quality of chemotherapy.RDI is the ratio of dose intensity received by patients vs.dose intensity recommended by the standard regimens.The relationship between chemotherapy dose intensity and clinical outcome has been studied in some trials.Most of the trials support the importance of sustaining full dose intensity in neoadjuvant and adjuvant chemotherapy,while others found the same clinical benefit of reducing RDI from the standard RDI for some regimens,but this remains the subject of much controversy.PurposeTo investigate the impact of chemotherapy relative dose intensity(RDI)on disease-free survival(DFS)and overall survival(OS).To identify the optimal RDI cut-off points with TEC regimen for stage Ⅰ-Ⅲ breast cancer patients and the adverse events in these patients.MethodsThis is a retrospective audit of a cohort of breast cancer patients treated in the first affiliated hospital of Chongqing medical university in2011 with TEC regimen for neoadjuvant and adjuvant therapy.Data were retrieved from electronic medical records system of the hospital and telephone follow-up.Women with TEC regimen diagnosed with stage Ⅰ-Ⅲ in 2011 with complete information on RDI were included.The three RDI cut-off points(90%,85%,80%)were evaluated on disease-free and overall survival.The survival time was calculated from the date of treatment to the date of death.The adverse events included hematological and nonhematological toxicity.The distributions of categorical variables between comparison groups were compared by Chi-square test.The survival difference was compared by Cox proportional hazards model and Kaplan-Meier curve.ResultsAmong 293 patients with TEC regimen,80% was the cut-off point at which the high RDI was associated with better overall survival.Among 169HR(+),85% was the cut-off points for DFS(HR = 2.44;95% CI 1.07-5.55;p = 0.03)and OS(HR = 2.48;95% CI 1.13-5.45;p=0.02).Among105 HR(-)patients,80% was the cut-off point for DFS(HR=3.03;95% CI1.03–8.93;p=0.045)and OS(HR=2.72;95% CI 1.01–7.33;p=0.048).Of 293 patients,neutropenia,nuasea,vomiting were found correlations with the level of RDI.ConclusionsHigher RDI of chemotherapy is associated with better survival for both HR(+)and HR(-)patients.To optimize survival benefits,RDI should be maintained ≥ 85% in HR(+)and ≥ 80% in HR(-)patients.Higher RDI of chemotherapy is connected with a higher probability of causing adverse events.