Treatment trends and factors associated with survival in T1aN0 and T1bN0 breast cancer patients.

BACKGROUND

Breast conservation therapy (BCT) and adjuvant hormonal therapy for estrogen-receptor positive breast cancers have become standard of care. Our objectives were to evaluate trends in the surgical management and adjuvant therapy for early-stage breast cancer and to identify factors predicting survival.

METHODS

Using the National Cancer Data Base (NCDB), patients with node-negative breast cancers less than 1 cm (T1aN0M0 and T1bN0M0) from 1993-2004 were identified. The time periods of 1993-1994, 1998-1999, and 2003-2004 were compared to analyze trends in surgical management and adjuvant therapy. Cox Proportional Hazards modeling was used to examine factors predicting survival.

RESULTS

Overall, 123,212 cases of T1aN0M0 or T1bN0M0 breast cancer were identified. The use of breast conservation surgery increased from 61.3% in 1993/1994 to 78.3% in 2003/2004 with a concomitant decrease in the use of mastectomy. The use of radiation therapy also increased from 51.9% in 1993/1994 to 62.0% in 2003/2004. Adjuvant hormonal therapy administration rose sharply from 26.7% in 1993/1994 to 44.7% in 2003/2004. After adjusting for potential confounders, the difference in 5-year survival rates for T1a (94.3%) and T1b (93.1%) tumors was marginal (P = .04). Age, grade, size, and failure of BCS patients to receive radiation therapy and hormonal therapy were independent predictors of a higher likelihood of death.

CONCLUSIONS

BCS utilization increased over time, but mastectomy rates may still be considered high given the small size of tumors in this cohort and the percent of patients eligible for BCT. The use of hormonal therapy increased significantly over the past decade. Further investigation into patient and physician factors affecting treatment choices is needed if BCT and hormonal therapy utilization is to increase.