Rattay et al reported 2 models for predicting acute skin radiation toxicity in patients being treated for breast cancer. One model predicts acute desquamation. The authors are from multiple institutions in Europe,
Patient selection: breast cancer treated with radiation from the REQUITE Breast Cohort
Outcome: acute desquamation (RTOG >= Grade 2b; CTCAE >= Grade 2)
Parameters:
(1) body mass index (BMI) in kg per square meter
(2) breast size (per sister size)
(3) hypofractionation
(4) boost (photon or electron therapy to tumor bed)
(5) ever smoked
|
Parameter
|
Finding
|
Point
|
|
BMI
|
|
0.111 * (BMI)
|
|
breast size
|
|
0.240
|
|
hypofractionation
|
no
|
0
|
|
|
yes
|
-2.592
|
|
boost
|
no
|
0
|
|
|
yes
|
0.606
|
|
ever smoked
|
no
|
0
|
|
|
yes
|
0.435
|
where:
• Breast size references www.sizechart.com/brasize/sistersize/index.html.
• For the EU classification there are 8 strap sizes and 12 cup sizes for each strap size.
• There are 19 rows in the table from 65AA to 100K. If 65AA is designated as 0, then 100K would be 18. The assumption that the sister size ranges from 0 to 18.
value of X =
= SUM(points for all of the parameters) - 7.226
probability of acute erythema =
= 1 / (1+ EXP((-1) * X))
Performance:
• The area under the ROC curve was 0.7.
