Cutting the risk.
Top Line: Lymphedema? That’s all radiation, right?
The Study: Not even close. Study after study has had trouble scape-goating radiation as a major contributor to lymphedema risk in women with breast cancer. This prospective lymphedema screening trial from MGH included over 1800 women treated for invasive breast cancer. Lymphedema here was defined as a 10% increase in arm volume at least 3 months after surgery. Lymphedema risk was compared among patients who had: sentinel node biopsy (SLNB) without regional nodal irradiation (RNI, 74%), SLNB+RNI (7%), axillary lymph node dissection (ALND) without RNI (5%), and ALND+RNI (14%). The cumulative incidence of lymphedema at 5 years for each group was: 8%, 11%, 25%, and 30%. As you can see, once again, the type of axillary surgery—not the addition of axillary radiation—was most strongly associated with developing lymphedema. Looked at another way, radiation increases the relative risk of lymphedema by 20-35% while a full dissection does by >200%. This all poses the provocative question of which therapy offers the best therapeutic ratio in the setting of post-mastectomy sentinel node positivity: completion dissection, adjuvant radiation, or neither?
TBL: Increasing the risk for lymphedema shouldn’t be a huge deterrent to recommending adjuvant radiation and, in fact, should be a big reason to continue forgoing full axillary dissections whenever safe to do so. | Naoum, J Clin Oncol 2020