Assessing the Effect of Carcinoembryonic Antigen Tumor Marker Progression on Survival after Mastectomy in Patients With Breast Cancer: A Joint Survival Longitudinal Approach

Background: Breast cancer remains the most prevalent neoplasm in women, with more than 450000 deaths each year, worldwide. In cancer researches, several factors such as serum tumor markers have an important role in screening, treatment, and recurrence of the disease. Carcinoembryonic antigen (CEA) is one of the most widely used serum tumor markers in the clinical evaluation of patients with breast cancer. This study aimed to evaluate whether increasing serum CEA levels is an indicator of breast cancer patient’s survival or not. Materials and Methods: This retrospective study was done at Hematology Department of Shafa Hospital of Ahvaz, southwest of Iran. Only those patients who had mastectomy during 2006-2014 and regularly referred to the hospital were included. The joint survival longitudinal model was applied to analyze the data. JM package in R software was used for joint modeling analysis. Results: The five-year survival rate was 73.0%. Age and follow-up time were associated with CEA tumor marker values. Higher age is associated with higher CEA values over time (P=0.0156). There was a significant linear increasing trend in CEA values over time (P=0.0465). There was a significant difference between patients with and without nodal involvement (HR [95% CI]: 1.880 [1.330- 5.565]; P=0.0298). There was a positive correlation between CEA tumor marker levels and death (HR [95% CI]: 2.770 [1.369-5.603]; P=0.0046). Conclusion: Higher age is associated with higher CEA values over time. The involvement of lymph nodes increases the hazard of death. Death is more likely to occur in patients with higher CEA tumor marker levels.