title: Ten-year locoregional recurrence risks in women with nodal micrometastatic breast cancer staged with axillary dissection.
abstract: OBJECTIVE
  To compare the locoregional recurrence (LRR) rates in patients with nodal mirometastases (pNmic) with those in patients with node-negative (pN0) and macroscopic node-positive (pNmac) breast cancer; and to evaluate the LRR rates according to locoregional treatment of pNmic disease.
  
  
  METHODS
  The subjects were 9,616 women diagnosed between 1989 and 1999 with Stage pT1-T2, pN0, pNmic, or pNmac, M0 breast cancer. All women had undergone axillary dissection. The Kaplan-Meier local recurrence, regional recurrence, and LRR rates were compared among those with pN0 (n=7,977), pNmic (n=490) and pNmac (n=1,149) and according to locoregional treatment. Multivariate analysis was performed to identify the significant factors associated with LRR.
  
  
  RESULTS
  The median follow-up was 11 years. The 10-year Kaplan-Meier recurrence rate in the pN0, pNmic, and pNmac cohorts was 6.1%, 6.8%, and 8.7% for local recurrence; 3.1%, 6.2%, and 10.3% for regional recurrence; and 8.0%, 11.6%, and 15.2% for LRR, respectively (all p<.001). In the pNmic patients, the 10-year regional recurrence rate was 6.4% with breast-conserving surgery plus breast radiotherapy (RT), 5.4% with breast-conserving surgery plus locoregional RT, 4.6% with mastectomy alone, 11.1% with mastectomy plus chest wall RT, and 10.7% with mastectomy plus locoregional RT. In patients with pNmic disease and age<45 years, Grade 3 histologic features, lymphovascular invasion, nodal ratio>0.25, and estrogen receptor-negative disease, the 10-year LRR rates were 15-20%. On multivariate analysis of the entire cohort, pNmic was associated with greater LRR than Stage pN0 (hazard ratio [HR], 1.6; p=.002). On multivariate analysis of pNmic patients only, age<45 years was associated with significantly greater LRR (HR, 1.9; p=.03), and trends for greater LRR were observed with a nodal ratio>0.25 (HR, 2.0; p=.07) and lymphovascular invasion (HR, 1.7; p=.07).
  
  
  CONCLUSIONS
  Women with pNmic had a greater risk of LRR than those with pN0 disease. Patients with pNmic in association with young age, Grade 3 histologic features, lymphovascular invasion, nodal ratio>0.25, and estrogen receptor-negative disease experienced 10-year LRR rates of ∼15-20%, warranting consideration of locoregional RT.
authors.affiliation: Department of Radiation Oncology, British Columbia Cancer Agency, Vancouver Island Centre, Victoria, BC, Canada.
authors.forename: Krystine
authors.initials: K
authors.lastname: Lupe
authors.forename: Pauline T
authors.initials: PT
authors.lastname: Truong
authors.forename: Cheryl
authors.initials: C
authors.lastname: Alexander
authors.forename: Caroline
authors.initials: C
authors.lastname: Speers
authors.forename: Scott
authors.initials: S
authors.lastname: Tyldesley
mesh_terms: D000328:Adult; D000367:Age Factors; D001365:Axilla; D001940:Breast / Q000473:pathology*; D001943:Breast Neoplasms / Q000453:epidemiology / Q000473:pathology* / Q000532:radiotherapy / Q000628:therapy; D003131:Combined Modality Therapy / Q000379:methods; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008197:Lymph Node Excision; D008207:Lymphatic Metastasis; D015412:Mastectomy, Segmental; D008875:Middle Aged; D015999:Multivariate Analysis; D061206:Neoplasm Micrometastasis / Q000473:pathology*; D009364:Neoplasm Recurrence, Local / Q000453:epidemiology; D009367:Neoplasm Staging / Q000379:methods*; D018570:Risk Assessment; D013997:Time Factors