Second cancers in children treated with modern radiotherapy techniques.
OBJECTIVE
The scattered radiation from the treatment volume might be more significant for children than for adults and, as a consequence, modern radiotherapy treatment techniques such as IMRT and passive proton therapy could potentially increase the number of secondary cancers. In this report, secondary cancer risk resulting from new treatment technologies was estimated for an adult prostate patient and a child.


METHODS
The organ equivalent dose (OED) concept with a linear-exponential, a plateau and a linear dose-response curve was applied to dose distributions of an adult prostate patient and a child with a rhabdomyosarcoma of the prostate. Conformal radiotherapy, IMRT with 6MV photons and proton therapy were planned. OED (cancer risk) was estimated for the whole body, the rectum and the bladder. In addition, relative cumulative risk was calculated.


RESULTS
Secondary cancer risk in the adult is not more than 15% it increased when IMRT or passive proton therapy was compared to conventional treatment planning. In the child, risk remains practically constant or was even reduced for proton therapy. The cumulative risk in the child relative to that in the adult can be as large as 10-15.


CONCLUSIONS
By a comparison between an adult patient and a child treated for a disease of the prostate, it was shown that modern radiotherapy techniques such as IMRT and proton therapy (active and passive) do not increase the risk for secondary cancers.
Schneider
Uwe
U
Department of Radiation Oncology and Nuclear Medicine, The Triemli Hospital and Vetsuisse Faculty, University of Zürich, Switzerland. uschneider@vetclinics.uzh.ch
Lomax
Antony
A
Timmermann
Beate
B
D019583:Dose Fractionation, Radiation; D004307:Dose-Response Relationship, Radiation; D006801:Humans; D007223:Infant; D008297:Male; D008875:Middle Aged; D009381:Neoplasms, Radiation-Induced / Q000517:prevention & control*; D011471:Prostatic Neoplasms / Q000532:radiotherapy*; D011829:Radiation Dosage; D011878:Radiotherapy / Q000009:adverse effects / Q000379:methods*; D011879:Radiotherapy Dosage; D011880:Radiotherapy Planning, Computer-Assisted; D012007:Rectum / Q000528:radiation effects; D012208:Rhabdomyosarcoma / Q000532:radiotherapy*; D018570:Risk Assessment; D012542:Scattering, Radiation; D001743:Urinary Bladder / Q000528:radiation effects; D014915:Whole-Body Counting