Risk of secondary cancers from scattered radiation during intensity-modulated radiotherapies for hepatocellular carcinoma

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Abstract

Purpose

To evaluate and compare the risks of secondary cancers from therapeutic doses received by patients with hepatocellular carcinoma (HCC) during intensity-modulated radiotherapy (IMRT), volumetric arc therapy (VMAT), and tomotherapy (TOMO).

Methods

Treatments for five patients with hepatocellular carcinoma (HCC) were planned using IMRT, VMAT, and TOMO. Based on the Biological Effects of Ionizing Radiation VII method, the excess relative risk (ERR), excess absolute risk (EAR), and lifetime attributable risk (LAR) were evaluated from therapeutic doses, which were measured using radiophotoluminescence glass dosimeters (RPLGDs) for each organ inside a humanoid phantom.

Results

The average organ equivalent doses (OEDs) of 5 patients were measured as 0.23, 1.18, 0.91, 0.95, 0.97, 0.24, and 0.20 Gy for the thyroid, lung, stomach, liver, small intestine, prostate (or ovary), and rectum, respectively. From the OED measurements, LAR incidence were calculated as 83, 46, 22, 30, 2 and 6 per 10 ⁴ person for the lung, stomach, normal liver, small intestine, prostate (or ovary), and rectum.

Conclusions

We estimated the secondary cancer risks at various organs for patients with HCC who received different treatment modalities. We found that HCC treatment is associated with a high secondary cancer risk in the lung and stomach.

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Most cited references 33

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Tolerance of normal tissue to therapeutic irradiation

B Emami, Padraic Lyman, A. Brown … (1991)

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Volumetric modulated arc therapy: IMRT in a single gantry arc.

Karl-Otto Bischoff (2007)

In this work a novel plan optimization platform is presented where treatment is delivered efficiently and accurately in a single dynamically modulated arc. Improvements in patient care achieved through image-guided positioning and plan adaptation have resulted in an increase in overall treatment times. Intensity-modulated radiation therapy (IMRT) has also increased treatment time by requiring a larger number of beam directions, increased monitor units (MU), and, in the case of tomotherapy, a slice-by-slice delivery. In order to maintain a similar level of patient throughput it will be necessary to increase the efficiency of treatment delivery. The solution proposed here is a novel aperture-based algorithm for treatment plan optimization where dose is delivered during a single gantry arc of up to 360 deg. The technique is similar to tomotherapy in that a full 360 deg of beam directions are available for optimization but is fundamentally different in that the entire dose volume is delivered in a single source rotation. The new technique is referred to as volumetric modulated arc therapy (VMAT). Multileaf collimator (MLC) leaf motion and number of MU per degree of gantry rotation is restricted during the optimization so that gantry rotation speed, leaf translation speed, and dose rate maxima do not excessively limit the delivery efficiency. During planning, investigators model continuous gantry motion by a coarse sampling of static gantry positions and fluence maps or MLC aperture shapes. The technique presented here is unique in that gantry and MLC position sampling is progressively increased throughout the optimization. Using the full gantry range will theoretically provide increased flexibility in generating highly conformal treatment plans. In practice, the additional flexibility is somewhat negated by the additional constraints placed on the amount of MLC leaf motion between gantry samples. A series of studies are performed that characterize the relationship between gantry and MLC sampling, dose modeling accuracy, and optimization time. Results show that gantry angle and MLC sample spacing as low as 1 deg and 0.5 cm, respectively, is desirable for accurate dose modeling. It is also shown that reducing the sample spacing dramatically reduces the ability of the optimization to arrive at a solution. The competing benefits of having small and large sample spacing are mutually realized using the progressive sampling technique described here. Preliminary results show that plans generated with VMAT optimization exhibit dose distributions equivalent or superior to static gantry IMRT. Timing studies have shown that the VMAT technique is well suited for on-line verification and adaptation with delivery times that are reduced to approximately 1.5-3 min for a 200 cGy fraction.

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Radiation-induced second cancers: the impact of 3D-CRT and IMRT.

Eric Hall, Cheng-Shie Wuu (2003)

Information concerning radiation-induced malignancies comes from the A-bomb survivors and from medically exposed individuals, including second cancers in radiation therapy patients. The A-bomb survivors show an excess incidence of carcinomas in tissues such as the gastrointestinal tract, breast, thyroid, and bladder, which is linear with dose up to about 2.5 Sv. There is great uncertainty concerning the dose-response relationship for radiation-induced carcinogenesis at higher doses. Some animal and human data suggest a decrease at higher doses, usually attributed to cell killing; other data suggest a plateau in dose. Radiotherapy patients also show an excess incidence of carcinomas, often in sites remote from the treatment fields; in addition there is an excess incidence of sarcomas in the heavily irradiated in-field tissues. The transition from conventional radiotherapy to three-dimensional conformal radiation therapy (3D-CRT) involves a reduction in the volume of normal tissues receiving a high dose, with an increase in dose to the target volume that includes the tumor and a limited amount of normal tissue. One might expect a decrease in the number of sarcomas induced and also (less certain) a small decrease in the number of carcinomas. All around, a good thing. By contrast, the move from 3D-CRT to intensity-modulated radiation therapy (IMRT) involves more fields, and the dose-volume histograms show that, as a consequence, a larger volume of normal tissue is exposed to lower doses. In addition, the number of monitor units is increased by a factor of 2 to 3, increasing the total body exposure, due to leakage radiation. Both factors will tend to increase the risk of second cancers. Altogether, IMRT is likely to almost double the incidence of second malignancies compared with conventional radiotherapy from about 1% to 1.75% for patients surviving 10 years. The numbers may be larger for longer survival (or for younger patients), but the ratio should remain the same.

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Author and article information

Contributors

Dong Wook Kim

Kwangzoo Chung

Weon Kuu Chung

Sun Hyun Bae

Dong Oh Shin

Seongeon Hong

Sung Ho Park

Sung-Yong Park

Chae-Seon Hong

Young Kyung Lim

Dongho Shin

Se Byeong Lee

Hyun-ho Lee

Jiwon Sung

Myonggeun Yoon

Journal

Journal ID (nlm-ta): Radiat Oncol

Journal ID (iso-abbrev): Radiat Oncol

Title: Radiation Oncology (London, England)

Publisher: BioMed Central

ISSN (Electronic): 1748-717X

Publication date Collection: 2014

Publication date (Electronic): 8 May 2014

Volume: 9

Page: 109

Affiliations

[1 ]Department of Radiation Oncology, KyungHee University Hospital at Gangdong, Seoul, Korea

[2 ]Deparment of Radiation Oncology, Samsung Medical Center, Seoul, Korea

[3 ]Department of Radiation Oncology, KyungHee University Medical Center, Seoul, Korea

[4 ]Department of Neurosurgery, Ulsan University Hospital, Ulsan, Korea

[5 ]Proton Therapy Center, McLaren Cancer Institute, Flint, USA

[6 ]Proton Therapy Center, National Cancer Center, Ilsan, Korea

[7 ]Department of Radiological Science, College of Health Science, Korea University, Jeongneung 3-dong, Seongbuk-gu, Seoul, Korea

Article

Publisher ID: 1748-717X-9-109

DOI: 10.1186/1748-717X-9-109

PMC ID: 4030012

PubMed ID: 24886163

SO-VID: dcb33ac9-81f2-4476-9890-ab9ccd25f49b

License:

This is an Open Access article distributed under the terms of the Creative Commons Attribution License ( http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly credited. The Creative Commons Public Domain Dedication waiver ( http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated.

Risk of secondary cancers from scattered radiation during intensity-modulated radiotherapies for hepatocellular carcinoma

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Abstract

Purpose

Methods

Results

Conclusions

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Karger: Oncology

Most cited references 33

Tolerance of normal tissue to therapeutic irradiation

Volumetric modulated arc therapy: IMRT in a single gantry arc.

Radiation-induced second cancers: the impact of 3D-CRT and IMRT.

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