Are there high-risk subgroups for isolated locoregional failure in patients who had T1/2 breast cancer with one to three positive lymph nodes and received mastectomy without radiotherapy?

BACKGROUND: To define the factors associated with increased risk of isolated locoregional failure that may justify postmastectomy radiotherapy in patients with T1/2 breast cancer and 1-3 positive lymph nodes.
METHODS: Between 1990 and 2002, 248 patients who had pT1-2 breast cancer and 1-3 positive lymph nodes were treated with mastectomy without radiotherapy (age 32-84, median 54).
RESULTS: Median follow-up time was 82 months (range 2-189 months). For all patients, the 8-year isolated locoregional failure-free rate was 95 %. In univariate analysis, hormone receptor status and administration of hormone therapy were statistically significant factors, and vascular invasion was the borderline significant factor for isolated locoregional failure-free rates (P = 0.0377, 0.0181, and 0.0555, respectively). The 8-year isolated locoregional failure-free rates were 98 % for patients with positive hormone receptor status and 90 % for patients with negative hormone receptor status, 97 % for patients who received hormone therapy and 89 % for patients who did not receive hormone therapy, 92 % for patients with vascular invasion and 97 % for patients without vascular invasion. In multivariate analysis for hormone receptor status and vascular invasion, the former was statistically significant (P = 0.0491) and the latter was borderline significant (P = 0.0664). When patients had both negative hormone receptor and positive vascular invasion status, the 8-year isolated locoregional failure-free rates decreased to 83 %.
CONCLUSIONS: With regard to patients who had pT1/2 breast cancer and 1-3 positive lymph nodes, isolated locoregional failure was not common in general; however, patients who had both negative hormone receptor status and vascular invasion were comparatively high-risk patients for isolated locoregional failure.