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The Study: The axillary lateral thoracic vessel junction (ALTJ) is a region lying just lateral to the pectoralis minor and just below the humeral head that contains the axillary vessels and the branching lateral thoracic vessels. A study in 2019 evaluated whether radiation dose to different parts of the axilla was associated with the risk of lymphedema in breast cancer patients. Among 8 anatomic regions, increasing dose to the ALTJ was associated with the risk of lymphedema. The best cut point was a minimum dose to the ALTJ of 38.6 Gy. More recently, a multivariable NTCP model of lymphedema after breast cancer radiation found that the number of lymph nodes dissected and the volume of the ALTJ receiving 35 Gy were the factors most strongly associated with lymphedema risk. Here we have another large study that sought to validate the association between ALTJ dose and lymphedema risk. The study included 378 patients who received regional nodal irradiation for stage II-III breast cancer. Most had mastectomy (70.9%) and axillary lymph node dissection (81.8%). The cumulative incidence of lymphedema at 5 years was 25.8%, and the median time to development of lymphedema was 18.9 months. The rate of lymphedema was significantly higher after ALND than SLNB (29.5% v 8.7%). The authors retrospectively contoured the ALTJ according to the method described in the original 2019 study. The ALTJ volume typically overlapped the chest wall and axilla PTVs. The mean ALTJ dose was 49.9 Gy (44.6 Gy in the 2019 study), and the median Dmin was 31.9 Gy. None of the ALTJ dose metrics they evaluated were associated with lymphedema risk. Although, they did not specifically evaluate the cut point of Dmin >38.6 Gy nor V35. On multivariable analysis, age, BMI, and extent of ALND were the factors associated with lymphedema risk.
TBL: This large study with longer clinical follow up found no association between dose to the ALTJ and lymphedema risk. Given the proximity of the ALTJ to standard RNI target volumes, the authors felt that target volume coverage should not be compromised just to reduce dose to the ALTJ region. | Healy, Int J Radiat Oncol Biol Phys 2023
The Study: The axillary lateral thoracic vessel junction (ALTJ) is a region lying just lateral to the pectoralis minor and just below the humeral head that contains the axillary vessels and the branching lateral thoracic vessels. A study in 2019 evaluated whether radiation dose to different parts of the axilla was associated with the risk of lymphedema in breast cancer patients. Among 8 anatomic regions, increasing dose to the ALTJ was associated with the risk of lymphedema. The best cut point was a minimum dose to the ALTJ of 38.6 Gy. More recently, a multivariable NTCP model of lymphedema after breast cancer radiation found that the number of lymph nodes dissected and the volume of the ALTJ receiving 35 Gy were the factors most strongly associated with lymphedema risk. Here we have another large study that sought to validate the association between ALTJ dose and lymphedema risk. The study included 378 patients who received regional nodal irradiation for stage II-III breast cancer. Most had mastectomy (70.9%) and axillary lymph node dissection (81.8%). The cumulative incidence of lymphedema at 5 years was 25.8%, and the median time to development of lymphedema was 18.9 months. The rate of lymphedema was significantly higher after ALND than SLNB (29.5% v 8.7%). The authors retrospectively contoured the ALTJ according to the method described in the original 2019 study. The ALTJ volume typically overlapped the chest wall and axilla PTVs. The mean ALTJ dose was 49.9 Gy (44.6 Gy in the 2019 study), and the median Dmin was 31.9 Gy. None of the ALTJ dose metrics they evaluated were associated with lymphedema risk. Although, they did not specifically evaluate the cut point of Dmin >38.6 Gy nor V35. On multivariable analysis, age, BMI, and extent of ALND were the factors associated with lymphedema risk.
TBL: This large study with longer clinical follow up found no association between dose to the ALTJ and lymphedema risk. Given the proximity of the ALTJ to standard RNI target volumes, the authors felt that target volume coverage should not be compromised just to reduce dose to the ALTJ region. | Healy, Int J Radiat Oncol Biol Phys 2023