Rattay et al reported 2 models for predicting acute skin radiation toxicity in patients being treated for breast cancer. One model predicts acute erythema. The authors are from multiple institutions in Europe,
Patient selection: breast cancer treated with radiation from the REQUITE Breast Cohort
Outcome: acute erythema RTOG or 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
(6) tamoxifen therapy
|
Parameter
|
Finding
|
Point
|
|
BMI
|
|
0.049 * (BMI)
|
|
breast size
|
|
0.1
|
|
hypofractionation
|
no
|
0
|
|
|
yes
|
-1.565
|
|
boost
|
no
|
0
|
|
|
yes
|
0.302
|
|
ever smoked
|
no
|
0
|
|
|
yes
|
0.308
|
|
tamoxifen therapy
|
no
|
0
|
|
|
yes
|
0.234
|
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) - 2.265
probability of acute erythema =
= 1 / (1+ EXP((-1) * X))
Performance:
• The area under the ROC curve was 0.65 which is suboptimal.
