Top Line: Should we treat axillary lymph node isolated tumor cells and micrometastases like node negative or node positive disease?
The Study: This large study compared treatment outcomes for women with early stage breast cancer treated in British Columbia between 2006 and 2011. Over 10,000 patients were included in the study and they had pT1-2 tumors and pN0 (n=7492), pN0(i+) (n=305), pNmi (n=619), or pN1a (n=1855) nodal disease. Patients with pN0(i+)-N1a disease were more likely to have larger tumors and LVI while those with pN1a disease were more likely to have triple negative or luminal b tumor subtype. Most patients received some form of adjuvant RT with <10% in each nodal group receiving no RT. Locoregional RT (i.e. nodal radiation) was used in 1.1% of those with pN0, 24.3% of those with pN0(i+), 45.7% of those with pN1mi, and 71.1% of those with pN1a disease. Among those treated with RT, 42% received a boost. Remembering this was a retrospective study with obvious clinicopathologic reasons why clinicians chose certain treatments, the rates of locoregional failure were similar among the nodal groups: 3.3% (N0), 6.9% (N0i+), 2.1% (N1mi), and 3.7% (N1a). Univariate analysis showed improved locoregional control with locoregional RT for those with pN1mi, but not pN0(i+) disease. However, that improvement did not remain significant on multivariate analysis (p=0.07). Only chemotherapy was significantly associated with improved locoregional control.
TBL: In this large cohort, the use of nodal radiation was more frequent with increasing burden of low-volume nodal disease, and this resulted in comparable rates of locoregional failure among nodal stages. However, this non-randomized comparison was not able to show a significant difference in outcomes between those who were or were not treated with nodal radiation. | Dosani, Int J Radiat Oncol Biol Phys 2022