Re: “The Early Detection of Breast Cancer Treatment-Related Lymphedema of the Arm” by Vaughan Keeley

Dear Editor:

We read with great interest the article entitled “The Early Detection of Breast Cancer Treatment-Related Lymphedema of the Arm” by Keeley. ¹ This study suggested that limb volume measurements are useful in the early detection and evaluation of lymphedema. Limb volume changes have been used for diagnosis and evaluation of lymphedema for a long time, and it is indisputable that changes of limb volume are essential for following the status of lymphedema. However, limb volume is also greatly affected by weight changes, especially in cases of long-term follow-up; there may be >10% change. For this reason, the effects of weight change would not be negligible. Furthermore, there is also a problem that it is impossible to compare appropriately between cases with different body sizes. Accordingly, we used the lymphedema index to correct for the effects of body weight and size.^2–5

There are two types of lymphedema indices: lower extremity lymphedema (LEL) index for the lower extremities and upper extremity lymphedema (UEL) index for the upper extremities, both of which are calculated from the circumference of the five points of extremities and body mass index (BMI) according to the following formulae: L E L i n d e x = C L 1 2 + C L 2 2 + C L 3 2 + C L 4 2 + C L 5 2 ∕ B M I U E L i n d e x = C U 1 2 + C U 2 2 + C U 3 2 + C U 4 2 + C U 5 2 ∕ B M I ,

where “C” denotes circumference of the limb in centimeters; C_L1 denotes 10 cm above the superior border of the patella, C_L2 at the superior border of the patella, C_L3 10 cm below the inferior border of the patella, C_L4 at the ankle, C_L5 at the foot, C_U1 5 cm above the olecranon, C_U2 at the olecranon, C_U3 5 cm below the olecranon, C_U4 at the wrist, and C_U5 at the hand.^2–5 Since LEL index and UEL index use circumferences of extremities and BMI, which are used in daily medical practice, it can be calculated and used immediately without special measurements. Because they are corrected for body size, comparisons between cases with different body sizes are possible.^2,3 Even if there are weight changes during the follow-up, the condition of lymphedema can be assessed more appropriately because the weight changes will be corrected by those indexes.^4,5

As we have discussed, in addition to measurement error, limb volume measurements have endogenous drawbacks due to body size and weight. If UEL index was used, the study results would be corrected by the body-type-adjusted volume evaluation. It is expected that lymphedema index will be used generally in the future because it can compensate for some of the shortcomings of limb volume measurements.