title: Influence of delayed initiation of adjuvant chemotherapy on breast cancer survival is subtype-dependent.
abstract: OBJECTIVE
  The optimal time from surgery to initiation of adjuvant chemotherapy of breast cancer is still controversial. We investigated the influence of time to adjuvant chemotherapy on survival outcomes according to breast cancer subtype.
  
  
  RESULTS
  Longer delay of initiation of adjuvant chemotherapy (≤4 weeks versus >8 weeks)) significantly decreased the DFS (adjusted hazard ratio [HR] of 1.86; 95% confidence interval [CI], 1.19-2.90) and OS (adjusted HR of 2.02; 95% CI, 1.10-3.71). However, a moderate delay (≤4 weeks versus 4-8 weeks) did not significantly influence the survival. We further investigated the effect of time to adjuvant chemotherapy (≤8 versus >8 weeks) on survival according to subtypes. Patients with luminal-A tumors who received delayed chemotherapy had no increased risk of recurrence (HR of 1.15; 95% CI, 0.54-2.43). In contrast, patients with luminal-B, triple-negative, or trastuzumab-untreated HER2-positive tumors would have decreased DFS because of delayed chemotherapy, with HR of 1.93 (95% CI, 1.10-3.34), 2.55 (95% CI, 1.25-5.18), and 2.41 (95% CI, 1.36-4.26), respectively.
  
  
  METHODS
  Operable women with stage I-IIIa breast cancer between 2003 and 2006 in our institution were included. 1,408 patients were divided into 3 groups according to the time to adjuvant chemotherapy: ≤4 weeks, 4-8 weeks, and >8 weeks. Disease-free survival (DFS) and overall survival (OS) were calculated.
  
  
  CONCLUSIONS
  Longer delay of adjuvant chemotherapy was associated with worse survival and early initiation of adjuvant chemotherapy should be performed for patients with aggressive tumor subtypes.
authors.affiliation: Department of Breast Surgery, Shanghai Cancer Center and Cancer Institute, Shanghai Medical College, Fudan University, Shanghai, P.R. China.
authors.forename: Ke-Da
authors.initials: KD
authors.lastname: Yu
authors.affiliation: Department of Breast Surgery, Shanghai Cancer Center and Cancer Institute, Shanghai Medical College, Fudan University, Shanghai, P.R. China.
authors.forename: Lei
authors.initials: L
authors.lastname: Fan
authors.affiliation: Department of Medical Oncology, Shanghai Cancer Center and Cancer Institute, Shanghai Medical College, Fudan University, Shanghai, P.R. China.
authors.forename: Li-Xin
authors.initials: LX
authors.lastname: Qiu
authors.affiliation: Department of Breast Surgery, Shanghai Cancer Center and Cancer Institute, Shanghai Medical College, Fudan University, Shanghai, P.R. China.
authors.forename: Hong
authors.initials: H
authors.lastname: Ling
authors.affiliation: Department of Breast Surgery, Shanghai Cancer Center and Cancer Institute, Shanghai Medical College, Fudan University, Shanghai, P.R. China.
authors.forename: Yi-Zhou
authors.initials: YZ
authors.lastname: Jiang
authors.affiliation: Department of Breast Surgery, Shanghai Cancer Center and Cancer Institute, Shanghai Medical College, Fudan University, Shanghai, P.R. China.
authors.forename: Zhi-Ming
authors.initials: ZM
authors.lastname: Shao
mesh_terms: D000971:Antineoplastic Combined Chemotherapy Protocols / Q000009:adverse effects / Q000627:therapeutic use*; D014408:Biomarkers, Tumor; D001943:Breast Neoplasms / Q000175:diagnosis / Q000188:drug therapy* / Q000401:mortality*; D017024:Chemotherapy, Adjuvant; D003131:Combined Modality Therapy; D005260:Female; D006801:Humans; D009362:Neoplasm Metastasis; D009367:Neoplasm Staging; D011379:Prognosis; D061665:Time-to-Treatment; D016896:Treatment Outcome; D047368:Tumor Burden
chemical_list: D014408:Biomarkers, Tumor
keywords: breast cancer; subtype; survival; timing of adjuvant chemotherapy