Frequency distribution of second solid cancer locations in relation to the irradiated volume among 115 patients treated for childhood cancer.
OBJECTIVE
To provide better estimates of the frequency distribution of second malignant neoplasm (SMN) sites in relation to previous irradiated volumes, and better estimates of the doses delivered to these sites during radiotherapy (RT) of the first malignant neoplasm (FMN).


METHODS
The study focused on 115 patients who developed a solid SMN among a cohort of 4581 individuals. The homemade software package Dos_EG was used to estimate the radiation doses delivered to SMN sites during RT of the FMN. Three-dimensional geometry was used to evaluate the distances between the irradiated volume, for RT delivered to each FMN, and the site of the subsequent SMN.


RESULTS
The spatial distribution of SMN relative to the irradiated volumes in our cohort was as follows: 12% in the central area of the irradiated volume, which corresponds to the planning target volume (PTV), 66% in the beam-bordering region (i.e., the area surrounding the PTV), and 22% in regions located more than 5 cm from the irradiated volume. At the SMN site, all dose levels ranging from almost zero to >75 Gy were represented. A peak SMN frequency of approximately 31% was identified in volumes that received <2.5 Gy.


CONCLUSIONS
A greater volume of tissues receives low or intermediate doses in regions bordering the irradiated volume with modern multiple-beam RT arrangements. These results should be considered for risk-benefit evaluations of RT.
Diallo
Ibrahima
I
U605 Institut National de la Santé et de la Recherche Médicale, Villejuif, France. ibrahim.diallo@igr.fr
Haddy
Nadia
N
Adjadj
Elisabeth
E
Samand
Akhtar
A
Quiniou
Eric
E
Chavaudra
Jean
J
Alziar
Iannis
I
Perret
Nathalie
N
Guérin
Sylvie
S
Lefkopoulos
Dimitri
D
de Vathaire
Florent
F
D000293:Adolescent; D002648:Child; D002675:Child, Preschool; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D009369:Neoplasms / Q000532:radiotherapy*; D009381:Neoplasms, Radiation-Induced / Q000473:pathology*; D016609:Neoplasms, Second Primary / Q000473:pathology*; D011879:Radiotherapy Dosage; D017741:Survivors