Population-based analysis of occult primary breast cancer with axillary lymph node metastasis.
BACKGROUND
Single-institution data suggest that treatment with radiation and axillary lymph node dissection (ALND) may be an appropriate alternative to mastectomy for T0N+ breast cancer. Population-based multi-institutional data supporting this approach are lacking.


METHODS
The cause-specific survival (CSS) and overall survival (OS) of women with T0N+M0 ductal, lobular, or mixed breast cancer in the Surveillance, Epidemiology, and End Results database from 1983 to 2006 were analyzed. Groups were defined as: 1) no ALND, mastectomy, or RT (observation); 2) ALND only; 3) mastectomy plus ALND with or without postmastectomy radiation (Mast); and 4) breast-conserving therapy (BCT) with ALND and radiation (BCT).


RESULTS
In total, 750 of 770,030 patients with breast cancer had T0N+M0 disease (incidence, 0.10%), and 596 of those patients underwent ALND (79.5%). Patients who underwent Mast or BCT (n = 470) had a 10-year OS rate of 64.9% compared with 58.5% for patients who underwent ALND only (n = 126; P = .02) and 47.5% for patients who underwent observation only (n = 94; P = .04). The 10-year CSS rate was 75.7% for patients who underwent BCT versus 73.9% for patients who underwent Mast (P = .55). In multivariate analysis of CSS for patients who underwent Mast or BCT, the following factors were correlated with an unfavorable outcome: positive estrogen receptor status (hazard ratio [HR], 0.48; 95% confidence interval [CI], 0.24-0.96; P = .04), >/=10 positive lymph nodes (HR, 5.7; 95%CI, 2.4-13.4; P </= .01), and <10 resected lymph nodes (HR, 42.9; 95%CI, 1.2-7.1; P = .02). Mast did not improve CSS compared with BCT (HR, 1.09; 95%CI, 0.57-2.1; P = .79).


CONCLUSIONS
Definitive locoregional treatment with either Mast or BCT improved the outcome of patients with T0N+breast cancer, and no difference in survival was observed between the treatments. Cancer 2010. (c) 2010 American Cancer Society.
Walker
Gary V
GV
Department of Radiation Oncology, The University of Texas M. D. Anderson Cancer Center, Houston, Texas 77030, USA.
Smith
Grace L
GL
Perkins
George H
GH
Oh
Julia L
JL
Woodward
Wendy
W
Yu
Tse-Kuan
TK
Hunt
Kelly K
KK
Hoffman
Karen
K
Strom
Eric A
EA
Buchholz
Thomas A
TA
D000328:Adult; D000368:Aged; D001365:Axilla; D001943:Breast Neoplasms / Q000175:diagnosis* / Q000453:epidemiology / Q000401:mortality / Q000473:pathology / Q000628:therapy; D003131:Combined Modality Therapy; D005260:Female; D006801:Humans; D008197:Lymph Node Excision; D008207:Lymphatic Metastasis; D008408:Mastectomy; D008875:Middle Aged; D009376:Neoplasms, Hormone-Dependent / Q000453:epidemiology; D011159:Population Surveillance; D018714:Radiotherapy, Adjuvant; D018426:SEER Program; D016896:Treatment Outcome