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Purpose
To
deter
mine the value of the intent to inclu
de internal
ma
mmary no
des (IMNs) in the ra
diation therapy (RT) volu
me for patients receiving a
djuvant locoregional (breast or chest wall plus axillary an
d supraclavicular fossa) RT for breast cancer.
Methods and Materials
2413 women with node-positive or T3/4N0 invasive breast cancer, treated with locoregional RT from 2001 to 2006, were identified in a prospectively maintained, population-based database. Intent to include IMNs in RT volume was determined through review of patient charts and RT plans. Distant relapse free survival (D-RFS), breast cancer-specific survival (BCSS), and overall survival (OS) were compared between the two groups. Prespecified pN1 subgroup analyses were performed.
Results
The median follow-up time was 6.2 years. Forty-one percent of study participants received IMN RT. The 5-year D-RFS for IMN inclusion and exclusion groups were 82 % vs. 82 % (m>pm> = 0.82), BCSS was 87 % vs. 87 % (m>pm> = 0.81), and OS was 85 % vs. 83 % (m>pm> = 0.06). In the pN1 subgroup, D-RFS was 90 % vs. 88 % (m>pm> = 0.31), BCSS was 94 % vs. 92 % (m>pm> = 0.18), and OS was 91 % vs. 88 % (m>pm> = 0.01). After potential confounding variables were controlled for, women who received IMN RT did not have significantly different D-RFS (hazard ratio [HR]?= 1.02 (95 % confidence interval [CI], 0.84-1.24; m>pm> = 0.85), BCSS (HR = 0.98 (95 % ?CI, 0.79-1.22; m>pm> = 0.88), or OS (HR = 0.95; 95 % CI, 0.78-1.15; m>pm> = 0.57). In the pN1 subgroup, IMN RT was associated with trends for improved survival that were not statistically significant: D-RFS (HR = 0.87; 95 % CI, 0.63-1.22; m>pm> = 0.42), BCSS (HR = 0.85; 95 % CI, 0.57-1.25; m>pm> = 0.39), and OS (HR = 0.78; 95 % CI, 0.56-1.09; m>pm> = 0.14).
Conclusions
After a median follow-up time of 6.2 years, although intentional IMN RT was not associated with a significant improvement in survival, this population-based study suggests that IMN RT may contribute to improved outcomes in selected patients with N1 disease.