title: Breast Cancer Survival Analysis Based on Immunohistochemistry Subtypes (ER/PR/HER2): a Retrospective Cohort Study.
abstract: BACKGROUND
  We conducted this study to estimate the prevalence of biomarkers, including estrogen receptor (ER), progesterone receptor (PR), and human epidermal growth factor receptor 2 (HER2) among patients with breast cancer and to explore their effects on disease mortality.
  
  
  METHODS
  We conducted this registry-based retrospective cohort study in Tehran, in 2014, using the data on 1622 patients with breast cancer, diagnosed pathologically and registered with the Comprehensive Cancer Control Center from 1998 to 2013. The outcome of interest was the survival probability of patients with breast cancer based on receptor status along with other prognostic factors such as age, histopathology, stage/grade of tumor, metastatic status, and surgical procedures using the life table, Kaplan-Meier curves, and multivariate Cox proportional hazard model. We generated different subtypes based on expression of ER, PR, and HER2, positive (+) and/or negative (-).
  
  
  RESULTS
  ER+/PR+/HER2- subtype (51.5%) was the most common form of breast cancer cells. Compared to the ER+/PR+/HER- subtype, the hazard ratio (95% confidence interval) of cancer mortality was 2.14 (1.13, 4.03) for ER-/PR-/HER2- subtype, 1.92 (1.03, 3.59) for ER-/PR-/HER2+ subtype and 5.19 (1.51, 17.86) for ER-/PR+/HER2+ subtype.
  
  
  CONCLUSIONS
  In this study, breast cancer cases with ER-/HER2+ tumors had shorter survival than those with ER+/PR+/HER2- tumors. Triple negative tumors were the only other subtype with a statistically significant poorer prognosis. The results of this study in a middle-income country further indicate the importance of receptor status, in particular HER2 status, in the prognosis of breast cancer.
authors.affiliation: Modeling of Noncommunicable Diseases Research Center and Department of Epidemiology, School of Public Health, Hamadan University of Medical Sciences, Hamadan, Iran.
authors.forename: Jalal
authors.initials: J
authors.lastname: Poorolajal
authors.affiliation: Cancer Research Center, Shahid Beheshti University of Medical Sciences, Tehran, Iran.
authors.forename: Nahid
authors.initials: N
authors.lastname: Nafissi
authors.affiliation: Cancer Research Center, Shahid Beheshti University of Medical Sciences, Tehran, Iran.
authors.forename: Mohammad Esmaeil
authors.initials: ME
authors.lastname: Akbari
authors.affiliation: Research Center for Health Sciences and Department of Biostatistics, School of Public Health, Hamadan University of Medical Sciences, Hamadan, Iran.
authors.forename: Hossein
authors.initials: H
authors.lastname: Mahjub
authors.affiliation: Kurdistan Research Center for Social Determinants of Health, School of Medicine, Kurdistan University of Medical Sciences, Sanandaj, Iran.
authors.forename: Nader
authors.initials: N
authors.lastname: Esmailnasab
authors.affiliation: Department of Epidemiology, School of Public Health, hamadan University of Medical Sciences, Hamadan, Iran.
authors.forename: Ebrahim
authors.initials: E
authors.lastname: Babaee
mesh_terms: D000293:Adolescent; D000328:Adult; D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D014408:Biomarkers, Tumor / Q000378:metabolism; D001943:Breast Neoplasms / Q000145:classification / Q000378:metabolism* / Q000401:mortality*; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D007492:Iran / Q000453:epidemiology; D053208:Kaplan-Meier Estimate; D008875:Middle Aged; D015999:Multivariate Analysis; D011379:Prognosis; D016016:Proportional Hazards Models; D018719:Erb-b2 Receptor Tyrosine Kinases / Q000378:metabolism*; D011960:Receptors, Estrogen / Q000378:metabolism*; D011980:Receptors, Progesterone / Q000378:metabolism*; D012189:Retrospective Studies; D055815:Young Adult
chemical_list: D014408:Biomarkers, Tumor; D018719:Erb-b2 Receptor Tyrosine Kinases; D011960:Receptors, Estrogen; D011980:Receptors, Progesterone; C508053:ERBB2 protein, human