Locoregional recurrence risk for patients with T1,2 breast cancer with 1-3 positive lymph nodes treated with mastectomy and systemic treatment.
OBJECTIVE
Postmastectomy radiation therapy (PMRT) has been shown to benefit breast cancer patients with 1 to 3 positive lymph nodes, but it is unclear how modern changes in management have affected the benefits of PMRT.


METHODS
We retrospectively analyzed the locoregional recurrence (LRR) rates in 1027 patients with T1,2 breast cancer with 1 to 3 positive lymph nodes treated with mastectomy and adjuvant chemotherapy with or without PMRT during an early era (1978-1997) and a later era (2000-2007). These eras were selected because they represented periods before and after the routine use of sentinel lymph node surgery, taxane chemotherapy, and aromatase inhibitors.


RESULTS
19% of 505 patients treated in the early era and 25% of the 522 patients in the later era received PMRT. Patients who received PMRT had significantly higher-risk disease features. PMRT reduced the rate of LRR in the early era cohort, with 5-year rates of 9.5% without PMRT and 3.4% with PMRT (log-rank P=.028) and 15-year rates 14.5% versus 6.1%, respectively; (Cox regression analysis: adjusted hazard ratio [AHR] 0.37, P=.035). However, PMRT did not appear to benefit patients treated in the later cohort, with 5-year LRR rates of 2.8% without PMRT and 4.2% with PMRT (P=.48; Cox analysis: AHR 1.41, P=.48). The most significant factor predictive of LRR for the patients who did not receive PMRT was the era in which the patient was treated (AHR 0.35 for later era, P<.001).


CONCLUSIONS
The risk of LRR for patients with T1,2 breast cancer with 1 to 3 positive lymph nodes treated with mastectomy and systemic treatment is highly dependent on the era of treatment. Modern treatment advances and the selected use of PMRT for those with high-risk features have allowed for identification of a cohort at very low risk for LRR without PMRT.
Department of Radiation Oncology, University of Texas MD Anderson Cancer Center, Houston, Texas; University of Arizona School of Medicine, Phoenix, Arizona.
Andrew
A
McBride
Department of Radiation Oncology, University of Texas MD Anderson Cancer Center, Houston, Texas.
Pamela
P
Allen
Department of Radiation Oncology, University of Texas MD Anderson Cancer Center, Houston, Texas.
Wendy
W
Woodward
Department of Radiation Oncology, University of Texas MD Anderson Cancer Center, Houston, Texas.
Michelle
M
Kim
Department of Surgical Oncology, University of Texas MD Anderson Cancer Center, Houston, Texas.
Henry M
HM
Kuerer
Department of Pathology, University of Texas MD Anderson Cancer Center, Houston, Texas.
Eva Katherine
EK
Drinka
Department of Pathology, University of Texas MD Anderson Cancer Center, Houston, Texas.
Aysegul
A
Sahin
Department of Radiation Oncology, University of Texas MD Anderson Cancer Center, Houston, Texas.
Eric A
EA
Strom
Department of Medical Oncology, University of Texas MD Anderson Cancer Center, Houston, Texas.
Aman
A
Buzdar
Department of Medical Oncology, University of Texas MD Anderson Cancer Center, Houston, Texas.
Vicente
V
Valero
Department of Medical Oncology, University of Texas MD Anderson Cancer Center, Houston, Texas.
Gabriel N
GN
Hortobagyi
Department of Surgical Oncology, University of Texas MD Anderson Cancer Center, Houston, Texas.
Kelly K
KK
Hunt
Department of Radiation Oncology, University of Texas MD Anderson Cancer Center, Houston, Texas. Electronic address: tbuchhol@mdanderson.org.
Thomas A
TA
Buchholz
D000328:Adult; D001943:Breast Neoplasms / Q000188:drug therapy / Q000453:epidemiology / Q000473:pathology / Q000517:prevention & control* / Q000532:radiotherapy / Q000601:surgery; D015331:Cohort Studies; D005260:Female; D006801:Humans; D008198:Lymph Nodes / Q000473:pathology; D008207:Lymphatic Metastasis; D008408:Mastectomy; D009364:Neoplasm Recurrence, Local / Q000453:epidemiology / Q000517:prevention & control*; D009367:Neoplasm Staging; D011182:Postoperative Care; D011878:Radiotherapy / Q000706:statistics & numerical data; D011879:Radiotherapy Dosage; D018714:Radiotherapy, Adjuvant; D012044:Regression Analysis; D012189:Retrospective Studies; D012306:Risk; D021701:Sentinel Lymph Node Biopsy; D013997:Time Factors