Standardization of whole breast radiotherapy is required for safe omission of axillary lymph node dissection in breast cancer patients

The purpose of this study was to assess the dose distribuon and coverage of level I-II axillary lymph nodes during whole breast tangenal field radiotherapy (RT) aer breast-conserving surgery in paents with breast cancer.
The level I-II axillary lymph node volumes were retrospecvely contoured by a single radiaon oncologist based on computed tomography simulaon data from 44 paents who underwent breast-conserving surgery without axillary dissecon and who received postoperave whole breast RT between January and December 2014. The dose distribuons of the whole breast tangenal RT fields were reassessed in relaon to the axillary level I and II lymph node volumes.
: The average doses delivered to level I and I axillary lymph nodes were 49.4% (range, 14.2–94.6) and 30.8% (range, 2.6–71.5) of the prescribed radiaon dose, respecvely. The volumes receiving at least 95% of the prescribed radiaon dose were 12.7% (range, 0–67.4%) for level I and 1.4% (range, 0– 7.7%) for level II nodes. Compared to thin paents, the average doses delivered to axillary lymph node levels I and II were significantly higher in overweight paents.
The radiaon dose coverage of axillary lymph nodes by whole breast tangenal RT varies greatly among paents. To safely omit axillary lymph node dissecon from the treatment of clinically axillary lymph node negave T1-2 breast cancer paents with 1–2 posive sennel lymph nodes, standardizaon and individualizaon of whole breast RT are necessary.