Indian Journal of Cancer
Home  ICS  Feedback Subscribe Top cited articles Login 
Users Online :1095
Small font sizeDefault font sizeIncrease font size
Navigate here
  Search
 
  
Resource links
 »  Similar in PUBMED
 »  Search Pubmed for
 »  Search in Google Scholar for
 »Related articles
 »  Article in PDF (265 KB)
 »  Citation Manager
 »  Access Statistics
 »  Reader Comments
 »  Email Alert *
 »  Add to My List *
* Registration required (free)  

 
  In this article
 »  Abstract
 » Introduction
 »  Materials and Me...
 » Results
 » Discussion
 » Conclusion
 »  References
 »  Article Figures

 Article Access Statistics
    Viewed173    
    Printed21    
    Emailed0    
    PDF Downloaded73    
    Comments [Add]    

Recommend this journal

 


 
  Table of Contents  
ORIGINAL ARTICLE
Year : 2018  |  Volume : 55  |  Issue : 4  |  Page : 372-376
 

The risk of secondary cancer in pediatric medulloblastoma patients due to three-dimensional conformal radiotherapy and intensity-modulated radiotherapy


1 Department of Biophysics, Faculty of Science, Cairo University, Cairo, Egypt
2 Department of Radiotherapy and Nuclear Medicine, National Cancer Institute, Cairo University, Giza; Department of Radiotherapy, Children Cancer Hospital, Cairo, Egypt

Date of Web Publication28-Feb-2019

Correspondence Address:
Reham S Sherif
Department of Biophysics, Faculty of Science, Cairo University, Cairo
Egypt
Login to access the Email id

Source of Support: None, Conflict of Interest: None


DOI: 10.4103/ijc.IJC_410_18

Rights and Permissions

 » Abstract 


BACKGROUND: Craniospinal irradiation (CSI) is the standard radiation therapy treatment for medulloblastoma. The aim of this study was to estimate and compare the lifetime risk of radiation-induced secondary cancer in pediatric medulloblastoma patients using three-dimensional conformal radiotherapy (3D-CRT) and intensity-modulated radiotherapy (IMRT). MATERIALS AND METHODS: 3D-CRT and IMRT plans were performed for 10 CSI pediatric patients. The average absorbed doses for organs at risk (OARs) was calculated from dose-volume histograms on the treatment planning system. The average lifetime risk of radiation-induced secondary cancer was then calculated. RESULTS: Lifetime risk of secondary cancer for CSI pediatric patients treated using IMRT decreases in some OARs compared with those treated using 3D-CRT. This is attributable to the decrease in the average absorbed dose in some OARs when using IMRT technique. CONCLUSION: Follow-up of medulloblastoma pediatric patients should be performed after ending the treatment course in order to diagnose early secondary tumors. IMRT technique is substantially better than 3D-CRT in terms of lifetime risk of radiation-induced secondary cancer, probably due to reduced dose to OARs especially to the thyroid, which is the most sensitive organ to radiation.


Keywords: Lifetime risk, medulloblastoma, pediatric patients, secondary cancer


How to cite this article:
Sherif RS, Elshemey WM, Attalla EM. The risk of secondary cancer in pediatric medulloblastoma patients due to three-dimensional conformal radiotherapy and intensity-modulated radiotherapy. Indian J Cancer 2018;55:372-6

How to cite this URL:
Sherif RS, Elshemey WM, Attalla EM. The risk of secondary cancer in pediatric medulloblastoma patients due to three-dimensional conformal radiotherapy and intensity-modulated radiotherapy. Indian J Cancer [serial online] 2018 [cited 2019 Mar 20];55:372-6. Available from: http://www.indianjcancer.com/text.asp?2018/55/4/372/253293





 » Introduction Top


Medulloblastoma is considered as one of the most common pediatric tumors of the central nervous system (CNS).[1] Craniospinal irradiation (CSI) is an important radiotherapy technique to control the cancer of the CNS.[2] Most of the patients requiring CSI treatment are children,[3],[4] so it is very important to study the long-term effects of cancer treatment. Developing a second cancer is one of the most serious possible late complications of cancer treatment. The risk of developing secondary cancer is greatly associated with the age of the patient at the time of exposure to radiotherapy.[5],[6],[7],[8] Pediatric patients are associated with an increased risk of a secondary cancer compared to adults.[9],[10],[11],[12],[13]

Three-dimensional conformal radiotherapy (3D-CRT) is the main radiotherapy technique used for the treatment of medulloblastoma in pediatric patients in some treatment centers worldwide.[14] Patients are treated in the supine position and carefully the junctions developed between opposed lateral cranial fields and a posterior spinal field are taken into consideration. It is a fact that in 3D-CRT large areas of normal tissue and organs at risk (OARs) nearer to the target receive considerable dose of radiation.[15],[16],[17],[18],[19] On the contrary, intensity-modulated radiotherapy (IMRT) technique increases the ability to maximize the dose to the tumor and spare normal tissues. Unfortunately, it may increase the risk of secondary cancers due to radiation leakage from the linear accelerator due to the increase in the number of beams and the number of monitor units (MUs).[3] Hall and Wuu [20] reported that IMRT may double the incidence of second malignancies compared with 3D-CRT. On the other hand, the results of Studenski et al.,[21] Brodin et al.,[22] and Suntornpong [23] suggest that IMRT potentially reduces the incidence of secondary cancer in pediatric patients.

Since 3D-CRT is routinely used for the treatment of pediatric medulloblastoma patients in some treatment centers worldwide,[14] it is extremely important to calculate the lifetime risk of secondary cancer for those patients to figure out if they are possibly facing higher lifetime risk compared with those treated using IMRT as reported by some of the previous studies.[20],[21],[22],[23]


 » Materials and Methods Top


Patients and treatment planning

Ten pediatric patients of ages between 7 and 13 years undergoing CSI as a part of treatment of medulloblastoma were chosen for this study.

Treatment was carried out using 3D-CRT in the supine position with the help of treatment plans performed on Elekta Monaco version 5.11 treatment planning system (Elekta CMS, Maryland Heights, MO) employing a collapsed cone algorithm.

Two opposed lateral cranial fields (gantry angles of 90° and 270° with collimator angles of 10° and 170°) were used for photon treatment plans in addition to one direct posterior spinal field (gantry angle of 180°) or, in some cases, two posterior oblique spinal fields (gantry angles of 160° and 200°) based on the case under treatment. Photon fields of 6 MV were used.

A radiation oncologist carried out the delineation of OARs (thyroid, lungs, stomach, liver, bladder, kidneys, and eyes) on the planning computed tomography images of each patient.

The conventional radiotherapy prescription dose for the treatment of high-risk medulloblastoma (36 Gy delivered in 20 fractions of 1.8 Gy per fraction) was applied to the craniospinal target.

In order to compare the lifetime risk between IMRT and 3D-CRT in medulloblastoma pediatric patients, IMRT planning was performed on the same patients and compared with 3D-CRT. IMRT plans were carried out on Elekta Monaco version 5.11 (Elekta CMS) with Monte Carlo algorithm at gantry angles of 180°, 240°, 310°, 50°, and 120° for cranium and spine.

The lifetime risk of radiation-induced secondary cancer after medulloblastoma treatment due to 3-dimensional conformal radiotherapy and intensity-modulated radiotherapy

To calculate the risk of induced secondary cancer for the OARs, the equivalent dose for these organs should be first calculated using the following equation:[24]

ET = DT × WR(1)

Where ET is the equivalent dose of organ T in Sv, DT is the mean absorbed dose by organ T, and WR is the radiation weighting factor which is equal to 1 for photons.

The lifetime risk of radiation-induced secondary cancer for all OARs was calculated (except for the kidneys and eyes, as there are no nominal risk coefficients [NRC] data available for such organs) using the values of NRCs from ICRP Publication 103[24] given by the following equation [25]:

Risk of radiation-induced secondary cancer (%) = ET × NRC.(2)

Statistical analysis

The mean and standard deviation values were calculated with the help of Microsoft Excel 2007. Duncan multiple range test (in SPSS 19 statistics software (IBM SPSS Statistics for Windows, Armonk, NY: IBM Corp) package) was used to calculate the statistical significance of data.


 » Results Top


Absorbed dose in organs at risks due to 3-dimensional conformal radiotherapy and intensity-modulated radiotherapy

[Figure 1] shows a comparison between the average absorbed dose of OARs (thyroid, right lung, left lung, stomach, liver, bladder, right kidney, left kidney, right eye, and left eye) calculated for 3D-CRT and IMRT. The average absorbed dose for thyroid, stomach, liver, right eye, and left eye is significantly (P < 0.05) lower for patients treated using IMRT (16.70 ± 1.8, 8.50 ± 0.6, 6.78 ± 0.5, 26.90 ± 0.3, and 28.00 ± 0.2 Gy, respectively) compared with those treated using 3D-CRT (30.00 ± 0.6, 10.6 ± 0.9, 8.58 ± 1.0, 33.00 ± 1.0, and 32.94 ± 0.7 Gy, respectively). On the other hand, the average absorbed dose for left lung and bladder is significantly (P < 0.05) higher for patients treated using IMRT compared with those treated using 3D-CRT. The maximum difference in absorbed dose among all OARs between the two techniques is reported for thyroid.
Figure 1: Average absorbed dose of organs at risks for 10 medulloblastoma pediatric patients for 3-dimensional conformal radiotherapy and intensity-modulated radiotherapy. The error bars represent the standard deviation from mean

Click here to view


Lifetime risk of secondary cancer in medulloblastoma pediatric patients due to 3-dimensional conformal radiotherapy and intensity-modulated radiotherapy

[Figure 2] shows a comparison between the average lifetime risk of radiation-induced secondary cancer of some OARs (thyroid, right lung, left lung, stomach, liver, and bladder) due to 3D-CRT and IMRT as calculated using the equation 2. The average lifetime risk of radiation-induced secondary cancer for thyroid, stomach, and liver is significantly (P < 0.05) lower for patients treated using IMRT (5.50 ± 0.6%, 6.70 ± 0.5%, and 2.00 ± 0.1%, respectively) compared with those treated using 3D-CRT (9.90 ± 0.2%, 8.40 ± 0.7%, and 2.6 ± 0.3%, respectively). On the other side, the average lifetime risk of radiation-induced secondary cancer for left lung and bladder is significantly (P < 0.05) higher for patients treated using IMRT compared with those treated using 3D-CRT. This is attributable to the higher average absorbed dose in these two OARs (left lung and bladder) for patients treated using IMRT compared with those treated using 3D-CRT.
Figure 2: Average lifetime risk of induced secondary cancer in various organs at risks for 10 medulloblastoma pediatric patients for 3-dimensional conformal radiotherapy and intensity-modulated radiotherapy. The error bars represent the standard deviation from mean

Click here to view



 » Discussion Top


Children are more susceptible to the risk of radiation-induced secondary cancers than adults due to the radiation sensitivity of their organs and tissues, the proximity of OARs and normal tissues to the treatment fields, the continuing development of their organs, and that they may survive several years after the treatment of the primary cancer.[26],[27],[28] Therefore, calculating the lifetime risk of radiation-induced secondary cancer is very important to understand whether the 3D-CRT technique that is routinely used in some treatment centers worldwide may be causing increased risk of radiation-induced secondary cancer that should be avoided.

Lee et al.[29] described the incidence and characteristics of secondary malignant neoplasms (SMNs) in adolescent and young adult cancer survivors compared with those in younger and older cancer survivors. They concluded that adolescent and young adults who survive after cancer treatment for more than 5 years have a higher relative risk of SMN compared with the general population and have a higher absolute risk of SMN compared with younger or older cancer survivors.

Stavrou et al.[30] also reported a significant increase in subsequent cancer with 4 of 88 patients diagnosed with secondary cancer within 10 years after radiation treatment.

According to a linear dose–response model, a general reduction in absorbed doses (reflected by mean dose to OARs) should be the aim in order to decrease the risk of radiation-induced secondary cancer.[2]

The present results show a significant decrease in the average absorbed dose (mean dose) for some OARs (thyroid, stomach, liver, and eyes) for patients treated using IMRT compared with those treated using 3D-CRT. These results agree with Studenski et al.[21] who compared the dosimetric advantages of IMRT and volumetric-modulated arc therapy (VMAT) with 3D-CRT planning in CSI patients for both cranial and spine fields. They reported that IMRT decreases the dose for OARs (thyroid, stomach, liver, small bowel, heart, esophagus, lungs, and kidneys) compared with each of VMAT or 3D-CRT.

Several models were presented by ICRP to predict the risk of radiation-induced cancer for radiotherapy doses based on the linear approximation of the risks of the atomic bomb survivors using the effective dose (the tissue-weighted sum of the equivalent doses in all specified tissues) for risk estimation. For fractionated dose, basic risk factors are usually modified by a dose and dose-rate effectiveness factor (DDREF, the ratio between the risk per unit effective dose for high dose rates and that for low dose rates).[31] If DDREF value of two is used when dealing with a fractionated dose,[25],[32] the risk of radiation-induced secondary cancer is expected to decrease to one-half of the values presented in [Figure 2], but still the difference between the risk of secondary cancer between IMRT and 3D-CRT remains the same.

Rehman et al.[33] evaluated the lifetime risk of secondary cancer from IMRT and 3D-CRT for spine radiotherapy. Their results indicated that IMRT had lower lifetime risk of secondary cancer than 3D-CRT for OARs (esophagus, lung, and bone surface).

Ardenfors et al.[34] compared the risk of radiation-induced secondary cancer for head and neck tumors due to IMRT and 3D-CRT. Their results indicated that the redistribution of the dose due to IMRT leads to a redistribution of the risks in individual tissues. However, the total levels of risk were similar between the two irradiation techniques.

Elgendy et al.[35] evaluated the risk of secondary cancer in 3D-CRT and IMRT for the infield and out-of-field organs from the primary radiation fields. Their results showed increase in dose for out-of-field OARs with IMRT plan compared with 3D-CRT, where in IMRT larger volume is irradiated to lower doses. This is because the total MUs in IMRT are higher than in 3D-CRT which increases the probability of induction of a second primary cancer in out-of-field OARs in IMRT than in 3D-CRT. The infield OARs receive lower doses with IMRT allowing significant reduction in the doses to infield OARs compared with 3D-CRT.

Contrary to the results by many authors (shown above), which all confirm that the lifetime risk associated with IMRT is considerably lower than 3D-CRT, Hall and Wuu [20] reported that IMRT may double the incidence of second malignancies compared with 3D-CRT.

Despite the fact that IMRT has been reported by several authors (including this study) to have lower lifetime risk compared with 3D-CRT, the latter has been reported by many authors to show lower lifetime risk compared with a number of advanced techniques.

Previous studies showed that the risk of radiation-induced secondary cancer in CSI patients, especially in the breast and lung, was higher in the case of tomotherapy (TOMO) compared with 3D-CRT.[11],[12],[36],[37],[38],[39] Holmes et al.[39] showed that in addition to the breast and lung, they found a significant increase in the risk of colorectal cancer using TOMO CSI compared with 3D-CRT.

Myers et al.[37] made a comparison among TOMO, VMAT, and 3D-CRT for CSI. They found that 3D-CRT plans had the lowest mean dose values compared with TOMO or VMAT.

Zhang et al.[1] compared proton and photon therapies in terms of the predicted risk of second cancers for a 4-year-old male medulloblastoma patient receiving CSI. They found that proton therapy conferred lower predicted risk of second cancer than photon therapy for the pediatric medulloblastoma patient. Athar and Paganetti [40] compared 6-MV IMRT and proton therapy in terms of organ-specific second cancer lifetime attributable risks caused by scattered and secondary out-of-field radiation. They found that for out-of-field risks, IMRT offered advantage close to the primary field. An increasing advantage for passive proton therapy was noticed with increasing distance to the field.

Yoon et al.[36] evaluated the dosimetric benefits of advanced radiotherapy techniques (3D-CRT, TOMO, and proton beam treatment [PBT]) for CSI in pediatric patients. Dosimetric benefits and organ-specific radiation-induced cancer risks were based on comparisons of dose-volume histograms and on the application of organ equivalent doses (OEDs), respectively. They found that PBT showed improvements in most dosimetric parameters for CSI patients, with lower OEDs to OARs compared with photon techniques. Eaton et al.[41] compared the long-term disease control and overall survival between children treated with proton and photon radiotherapies for standard risk medulloblastoma. They found that disease control with proton and photon radiotherapy appeared equivalent for standard risk medulloblastoma.

Kirsch and Tarbell [42] compared the long-term side effects of treatment due to high-energy X-rays (photons) and proton radiation therapy for children with brain tumors. They suggested that proton beam radiation therapy might limit the late effects of radiation therapy and therefore offer an advantage over techniques using photons. Yuh et al.[43] reported that proton beam technique for CSI of pediatric medulloblastoma had successfully reduced normal tissue doses and acute treatment-related sequelae. They added that this technique might be especially advantageous in children with a history of myelosuppression, who might not otherwise tolerate irradiation.

St. Clair et al.[44] compared treatment plans from standard photon therapy, intensity-modulated X-rays (IMRT), and protons for craniospinal axis irradiation and posterior fossa boost in a patient with medulloblastoma. Their study demonstrated the advantage of conformal radiation methods for the treatment of posterior fossa and spinal column in children with medulloblastoma, when compared with conventional X-rays. They added that between the two conformal treatment methods evaluated, protons were found to be superior to IMRT. Newhauser et al.[45] compared the risk of developing a second cancer after CSI using photon versus proton radiotherapy by means of simulation studies designed to account for the effects of neutron exposures. Simulations revealed that both passively scattered and scanned beam proton therapies conferred significantly lower risks of second cancers than 6-MV conventional and intensity-modulated (IM) photon therapies.

Miralbell et al.[11] assessed the potential influence of improved dose distribution with proton beams compared with conventional or IM X-ray beams on the incidence of treatment-induced secondary cancers in medulloblastoma pediatric patient. They found that proton beams reduced the expected incidence of radiation-induced secondary cancers in the medulloblastoma case by a factor of 8–15 when compared with either IM or conventional X-ray plans.


 » Conclusion Top


Follow-up of pediatric medulloblastoma patients is recommended after the course of their treatment in order to diagnose any secondary cancer at early stages. IMRT technique is recommended in the treatment of medulloblastoma pediatric patients compared with 3D-CRT as it can reduce the dose and consequently the lifetime risk of radiation-induced secondary cancer in some OARs which include the most radiosensitive organ (thyroid). This is very important for pediatric patients because they are more susceptible to the risk of radiation-induced secondary cancer than adults as they are expected to survive several decades after the radiation treatment. It is important to consider the use of proton therapy when available as there is evidence in literature that it may probably offer reduced lifetime risk of radiation-induced secondary cancer compared with the discussed techniques.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.



 
 » References Top

1.
Zhang R, Howell RM, Giebeler A, Taddei PJ, Mahajan A, Newhauser WD, et al. Comparison of risk of radiogenic second cancer following photon and proton craniospinal irradiation for a pediatric medulloblastoma patient. Phys Med Biol 2013;58:807-23.  Back to cited text no. 1
    
2.
Stokkevåg CH, Engeseth GM, Ytre-Hauge KS, Röhrich D, Odland OH, Muren LP, et al. Estimated risk of radiation-induced cancer following paediatric cranio-spinal irradiation with electron, photon and proton therapy. Acta Oncol 2014;53:1048-57.  Back to cited text no. 2
    
3.
Strodtbeck K, Sloan A, Rogers L, Fisher PG, Stearns D, Campbell L, et al. Risk of subsequent cancer following a primary CNS tumor. J Neurooncol 2013;112:285-95.  Back to cited text no. 3
    
4.
Packer RJ, Zhou T, Holmes E, Vezina G, Gajjar A. Survival and secondary tumors in children with medulloblastoma receiving radiotherapy and adjuvant chemotherapy: Results of children's oncology group trial A9961. Neuro Oncol 2013;15:97-103.  Back to cited text no. 4
    
5.
Friedman DL, Whitton J, Leisenring W, Mertens AC, Hammond S, Stovall M, et al. Subsequent neoplasms in 5-year survivors of childhood cancer: The childhood cancer survivor study. J Natl Cancer Inst 2010;102:1083-95.  Back to cited text no. 5
    
6.
MacArthur AC, Spinelli JJ, Rogers PC, Goddard KJ, Phillips N, McBride ML, et al. Risk of a second malignant neoplasm among 5-year survivors of cancer in childhood and adolescence in British Columbia, Canada. Pediatr Blood Cancer 2007;48:453-9.  Back to cited text no. 6
    
7.
Olsen JH, Möller T, Anderson H, Langmark F, Sankila R, Tryggvadóttír L, et al. Lifelong cancer incidence in 47,697 patients treated for childhood cancer in the Nordic countries. J Natl Cancer Inst 2009;101:806-13.  Back to cited text no. 7
    
8.
Reulen RC, Frobisher C, Winter DL, Kelly J, Lancashire ER, Stiller CA, et al. Long-term risks of subsequent primary neoplasms among survivors of childhood cancer. JAMA 2011;305:2311-9.  Back to cited text no. 8
    
9.
Schneider U, Walsh L. Cancer risk estimates from the combined Japanese A-bomb and Hodgkin cohorts for doses relevant to radiotherapy. Radiat Environ Biophys 2008;47:253-63.  Back to cited text no. 9
    
10.
Schneider U, Kaser-Hotz B. Radiation risk estimates after radiotherapy: Application of the organ equivalent dose concept to plateau dose-response relationships. Radiat Environ Biophys 2005;44:235-9.  Back to cited text no. 10
    
11.
Miralbell R, Lomax A, Cella L, Schneider U. Potential reduction of the incidence of radiation-induced second cancers by using proton beams in the treatment of pediatric tumors. Int J Radiat Oncol Biol Phys 2002;54:824-9.  Back to cited text no. 11
    
12.
Mu X, Björk-Eriksson T, Nill S, Oelfke U, Johansson KA, Gagliardi G, et al. Does electron and proton therapy reduce the risk of radiation induced cancer after spinal irradiation for childhood medulloblastoma? A comparative treatment planning study. Acta Oncol 2005;44:554-62.  Back to cited text no. 12
    
13.
Schneider U, Zwahlen D, Ross D, Kaser-Hotz B. Estimation of radiation-induced cancer from three-dimensional dose distributions: Concept of organ equivalent dose. Int J Radiat Oncol Biol Phys 2005;61:1510-5.  Back to cited text no. 13
    
14.
Rembielak A, Woo TC. Intensity-modulated radiation therapy for the treatment of pediatric cancer patients. Nat Clin Pract Oncol 2005;2:211-7.  Back to cited text no. 14
    
15.
Dieckmann K, Widder J, Pötter R. Long-term side effects of radiotherapy in survivors of childhood cancer. Front Radiat Ther Oncol 2002;37:57-68.  Back to cited text no. 15
    
16.
de Graaf SS, van Gent H, Reitsma-Bierens WC, van Luyk WH, Dolsma WV, Postma A, et al. Renal function after unilateral nephrectomy for Wilms' tumour: The influence of radiation therapy. Eur J Cancer 1996;32A: 465-9.  Back to cited text no. 16
    
17.
Paulino AC, Wen BC, Brown CK, Tannous R, Mayr NA, Zhen WK, et al. Late effects in children treated with radiation therapy for Wilms' tumor. Int J Radiat Oncol Biol Phys 2000;46:1239-46.  Back to cited text no. 17
    
18.
Pötter R, Roes F, Schellong G, Bartenstein P, Brämswig JH, von Lengerke HJ, et al. Subclinical impairment of renal function after radiotherapy for Hodgkin's disease in children. Recent Results Cancer Res 1993;130:259-67.  Back to cited text no. 18
    
19.
Schwartz CL. Long-term survivors of childhood cancer: The late effects of therapy. Oncologist 1999;4:45-54.  Back to cited text no. 19
    
20.
Hall EJ, Wuu CS. Radiation-induced second cancers: The impact of 3D-CRT and IMRT. Int J Radiat Oncol Biol Phys 2003;56:83-8.  Back to cited text no. 20
    
21.
Studenski MT, Shen X, Yu Y, Xiao Y, Shi W, Biswas T, et al. Intensity-modulated radiation therapy and volumetric-modulated arc therapy for adult craniospinal irradiation – A comparison with traditional techniques. Med Dosim 2013;38:48-54.  Back to cited text no. 21
    
22.
Brodin NP, Munck af Rosenschöld P, Blomstrand M, Kiil-Berthlesen A, Hollensen C, Vogelius IR, et al. Hippocampal sparing radiotherapy for pediatric medulloblastoma: Impact of treatment margins and treatment technique. Neuro Oncol 2014;16:594-602.  Back to cited text no. 22
    
23.
Suntornpong N. Intensity modulated radiation therapy in pediatric cancer; clinical outcome and risk of radiation-induced malignancies. Siriraj Med J 2015;67:41-5.  Back to cited text no. 23
    
24.
ICRP. International Commission on Radiological Protection (ICRP) Publication 103: Recommendations of the ICRP. Washington, DC: Elsevier; 2007.  Back to cited text no. 24
    
25.
Sherif RS, Attalla EM, Elshemey WM, Madian NG. The risk of secondary cancer in nasopharyngeal carcinoma paediatric patients due to intensity modulated radiotherapy and mega-voltage cone beam computed tomography. J Med Imaging Radiat Oncol 2017;61:402-9.  Back to cited text no. 25
    
26.
Brenner D, Elliston C, Hall E, Berdon W. Estimated risks of radiation-induced fatal cancer from pediatric CT. AJR Am J Roentgenol 2001;176:289-96.  Back to cited text no. 26
    
27.
Pierce DA, Shimizu Y, Preston DL, Vaeth M, Mabuchi K. Studies of the mortality of atomic bomb survivors. Report 12, part I. Cancer: 1950-1990. Radiat Res 1996;146:1-27.  Back to cited text no. 27
    
28.
UNSCEAR. Report of the United Nations Scientific Committee on the Effects of Atomic Radiation: Sixtieth Session (27-31 May, 2013). New York, USA: UNSCEAR; 2013.  Back to cited text no. 28
    
29.
Lee JS, DuBois SG, Coccia PF, Bleyer A, Olin RL, Goldsby RE, et al. Increased risk of second malignant neoplasms in adolescents and young adults with cancer. Cancer 2016;122:116-23.  Back to cited text no. 29
    
30.
Stavrou T, Bromley CM, Nicholson HS, Byrne J, Packer RJ, Goldstein AM, et al. Prognostic factors and secondary malignancies in childhood medulloblastoma. J Pediatr Hematol Oncol 2001;23:431-6.  Back to cited text no. 30
    
31.
Schneider U. Modeling the risk of secondary malignancies after radiotherapy. Genes (Basel) 2011;2:1033-49.  Back to cited text no. 31
    
32.
Yu CC, Hsu FY, Yu WH, Liu MT, Huang SS. Assessing doses of radiotherapy with the risk of developing cancer in the head and neck. Radiat Measurements 2011;46:1948-51.  Back to cited text no. 32
    
33.
Rehman JU, Tailor RC, Isa M, Afzal M, Chow J, Ibbott GS, et al. Evaluations of secondary cancer risk in spine radiotherapy using 3DCRT, IMRT, and VMAT: A phantom study. Med Dosim 2015;40:70-5.  Back to cited text no. 33
    
34.
Ardenfors O, Josefsson D, Dasu A. Are IMRT treatments in the head and neck region increasing the risk of secondary cancers? Acta Oncol 2014;53:1041-7.  Back to cited text no. 34
    
35.
Elgendy RA, Attalla EM, Elnaggar MA, Kotb MA. Evaluation of the second cancer's risk in conformal therapy and intensity modulated radiotherapy for the organs inside the primary radiation fields. J Appl Phys 2016;8:44-52.  Back to cited text no. 35
    
36.
Yoon M, Shin DH, Kim J, Kim JW, Kim DW, Park SY, et al. Craniospinal irradiation techniques: A dosimetric comparison of proton beams with standard and advanced photon radiotherapy. Int J Radiat Oncol Biol Phys 2011;81:637-46.  Back to cited text no. 36
    
37.
Myers PA, Mavroidis P, Komisopoulos G, Papanikolaou N, Stathakis S. Pediatric cranio-spinal axis irradiation: Comparison of radiation-induced secondary malignancy estimations based on three methods of analysis for three different treatment modalities. Technol Cancer Res Treat 2015;14:169-80.  Back to cited text no. 37
    
38.
Brodin NP, Munck Af Rosenschöld P, Aznar MC, Kiil-Berthelsen A, Vogelius IR, Nilsson P, et al. Radiobiological risk estimates of adverse events and secondary cancer for proton and photon radiation therapy of pediatric medulloblastoma. Acta Oncol 2011;50:806-16.  Back to cited text no. 38
    
39.
Holmes JA, Chera BS, Brenner DJ, Shuryak I, Wilson AK, Lehman-Davis M, et al. Estimating the excess lifetime risk of radiation induced secondary malignancy (SMN) in pediatric patients treated with craniospinal irradiation (CSI): Conventional radiation therapy versus helical intensity modulated radiation therapy. Pract Radiat Oncol 2017;7:35-41.  Back to cited text no. 39
    
40.
Athar BS, Paganetti H. Comparison of second cancer risk due to out-of-field doses from 6-MV IMRT and proton therapy based on 6 pediatric patient treatment plans. Radiother Oncol 2011;98:87-92.  Back to cited text no. 40
    
41.
Eaton BR, Esiashvili N, Kim S, Weyman EA, Thornton LT, Mazewski C, et al. Clinical outcomes among children with standard-risk medulloblastoma treated with proton and photon radiation therapy: A comparison of disease control and overall survival. Int J Radiat Oncol Biol Phys 2016;94:133-8.  Back to cited text no. 41
    
42.
Kirsch DG, Tarbell NJ. New technologies in radiation therapy for pediatric brain tumors: The rationale for proton radiation therapy. Pediatr Blood Cancer 2004;42:461-4.  Back to cited text no. 42
    
43.
Yuh GE, Loredo LN, Yonemoto LT, Bush DA, Shahnazi K, Preston W, et al. Reducing toxicity from craniospinal irradiation: Using proton beams to treat medulloblastoma in young children. Cancer J 2004;10:386-90.  Back to cited text no. 43
    
44.
St. Clair WH, Adams JA, Bues M, Fullerton BC, La Shell S, Kooy HM, et al. Advantage of protons compared to conventional X-ray or IMRT in the treatment of a pediatric patient with medulloblastoma. Int J Radiat Oncol Biol Phys 2004;58:727-34.  Back to cited text no. 44
    
45.
Newhauser WD, Fontenot JD, Mahajan A, Kornguth D, Stovall M, Zheng Y, et al. The risk of developing a second cancer after receiving craniospinal proton irradiation. Phys Med Biol 2009;54:2277-91.  Back to cited text no. 45
    


    Figures

  [Figure 1], [Figure 2]



 

Top
Print this article  Email this article
 

    

  Site Map | What's new | Copyright and Disclaimer
  Online since 1st April '07
  © 2007 - Indian Journal of Cancer | Published by Wolters Kluwer - Medknow