Outcomes of Trastuzumab Therapy for 6 and 12 Months in Indonesian National Health Insurance System Clients with Operable HER2-Positive Breast Cancer

OBJECTIVE: The aim of this study is to determine the outcome of trastuzumab therapy for 6 or 12 months in patients with HER2 positive operable breast cancer who followed the national health insurance system in Indonesia. METHODS: Data were extracted from medical records of Dr. M Djamil General Hospital Padang and Dharmais Cancer Hospital/ National Cancer Center Jakarta for post-operative breast HER-2 positive cancer patients treated with trastuzumab for 6 or 12 months who had been followed up for at least 5 years (January 1st in 2010 until December 31st in 2015). Disease free survival and overall survival rates and their relationship with trastuzumab duration was investigated using survival analysis (the Kaplan-Meier method and log rank test). Data were analyzed using the STATA program. RESULTS: A total of 121 women fulfilled the criteria of the study, 80 who had received trastuzumab for 6 months and 41 patients who received 12 months’ therapy. Disease free survival was 54 months (95% CI 45-63) compared with 63 months (95% CI 54-72), respectively. The log-rank test p value was 0.048 so the 12 months’ treatment regime did result in a significantly lower probability of recurrence compared with the 6 months’ regime (HR = 2.6). Analysis of the overall survival rate revealed median survival of 57 months (95% CI 49-64) for 6 months’ therapy compared to 62 months (95% CI 53-72) for 12 months. However, the log-rank test p value of 0.073 indicated that the extra six months of therapy did not decrease the probability of death (HR = 2.4). CONCLUSION: Trastuzumab therapy for 12 months reduced the recurrence rate in post-operative breast HER-2 positive cancer patients but did not significantly reduce mortality.