In a recent publication titled “Comparison of Breast Cancer Recurrence and Outcome Patterns Between Patients Treated From 1986 to 1992 and From 2004 to 2008”, published in the Journal of Clinical Oncology, a team of researchers from the Vancouver Cancer Centre, designed a study to determine if the patterns of relapse in breast cancer, considering the estrogen receptor (ER) and human epidermal growth factor receptor 2 (HER2) phenotype, have been altered throughout time.
As such, the research team analyzed data from women registered in the British Columbia Cancer Agency who had undergone biopsies to diagnose stage I to III breast cancer between the time period of 1986 and 1992 (cohort 1 [C1]) and 2004 and 2008 (cohort 2 [C2]). Furthermore, these patients’ ER and HER2 status were known. After all data were gathered, the team grouped a total of 7,178 C1 and C2 patients according to cancer stage, grade, and ER and HER2 phenotype.
The main outcomes of this study included hazard rate of relapse (HRR) for breast cancer according to biomarker status, stage, grade, and age, along with hazard rate of death (HRD).
The results showed that among all patients, 70.8% were ER positive/HER2 negative, 6.9% were ER positive/HER2 positive, 6.6% were ER negative/HER2 positive, and 15.8% were ER negative/HER2 negative.
The hazard rate of relapse was reduced to half in yearly intervals up to 9 years in the C2 group when compared to C1 and these differences were bigger in the first 5 intervals for HER2-positive and ER-negative/HER2-negative breast cancer patients.
Additionally, the researchers observed that the hazard rate of relapse was consistently lowered in the C2 cohort when compared to C1, for all breast cancer stages and grades.
Importantly, even though at a lower degree, the hazard rate of death was smaller in C2 compared to C1.
The results from this study let the team to conclude that even though there are similarities between the patterns of relapse between the two cohorts analyzed, there have been substantial advances in breast cancer relapse-free survival.
According to the authors, these risk parameters are of great importance when considering treatment decisions, patient consultation and clinical trial design.