Long-term outcomes of non-metastatic breast cancer patients by molecular subtypes.

ABSTRACT

BACKGROUND: Today, with the progress of medical sciences, increasing the cure probability and survival time is an important goal of cancer treatment. This study compared long-term disease-free survival (DFS) of non-metastatic breast cancer patients based on different molecular subtypes. METHODS: This retrospective cohort study consisted of 1287 patients diagnosed with breast cancer and treated at Motamed Cancer Institute from 2000 to 2016 and followed up until 2018. Kaplan-Meier curve was fitted to data based on molecular subtypes. Then the semi-parametric mixture cure model was applied to determine the survival and cure probability of molecular subtypes by adjusting clinical and demographic factors. RESULTS: Among 1287 breast cancer patients, 200 (15.5%) cases died. The mean age of patients was 47.00 ± 10.72 years. Women with the HR+/HER2-subtype had the best 5-year survival rate (84.2%), whereas other subtypes had a lower rate as follows HR+/HER2+ (77.3%), triple-negative (76.5%), and HR-/HER2+ (62.3%). Kaplan-Meier curve calculated a cure rate of about 60% and patients who survived more than 150 months were intuitively considered cured. After adjustment for clinical and demographic variables, the cure probability of HR-/Her2+ patients was substantially lower than HR+/HER2- patients (OR = 0.22), though there were no significant variations in short-term DFS based on molecular subtypes (HR = 0.91). CONCLUSIONS: Our results confirm that the most prevalent breast cancer was HR+/HER2- tumor type which had the best prognosis. It is also concluded that HR-/HER2+ patients had the worst outcomes, with the highest rates of recurrence and metastasis and the lowest overall and disease-free survival rates.