Volumetric intensity-modulated Arc (RapidArc) therapy for primary hepatocellular carcinoma: comparison with intensity-modulated radiotherapy and 3-D conformal radiotherapy

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Abstract

Background

To compare the RapidArc plan for primary hepatocellular carcinoma (HCC) with 3-D conformal radiotherapy (3DCRT) and intensity-modulated radiotherapy (IMRT) plans using dosimetric analysis.

Methods

Nine patients with unresectable HCC were enrolled in this study. Dosimetric values for RapidArc, IMRT, and 3DCRT were calculated for total doses of 45~50.4 Gy using 1.8 Gy/day. The parameters included the conformal index (CI), homogeneity index (HI), and hot spot (V _107%) for the planned target volume (PTV) as well as the monitor units (MUs) for plan efficiency, the mean dose (D _mean) for the organs at risk (OAR) and the maximal dose at 1% volume (D _1%) for the spinal cord. The percentage of the normal liver volume receiving ≥ 40, > 30, > 20, and > 10 Gy (V _{40 Gy}, V _{30 Gy}, V _{20 Gy}, and V _{10 Gy}) and the normal tissue complication probability (NTCP) were also evaluated to determine liver toxicity.

Results

All three methods achieved comparable homogeneity for the PTV. RapidArc achieved significantly better CI and V _107%values than IMRT or 3DCRT ( p < 0.05). The MUs were significantly lower for RapidArc (323.8 ± 60.7) and 3DCRT (322.3 ± 28.6) than for IMRT (1165.4 ± 170.7) ( p < 0.001). IMRT achieved a significantly lower D _meanof the normal liver than did 3DCRT or RapidArc ( p = 0.001). 3DCRT had higher V _{40 Gy}and V _{30 Gy}values for the normal liver than did RapidArc or IMRT. Although the V _{10 Gy}to the normal liver was higher with RapidArc (75.8 ± 13.1%) than with 3DCRT or IMRT (60.5 ± 10.2% and 57.2 ± 10.0%, respectively; p < 0.01), the NTCP did not differ significantly between RapidArc (4.38 ± 2.69) and IMRT (3.98 ± 3.00) and both were better than 3DCRT (7.57 ± 4.36) ( p = 0.02).

Conclusions

RapidArc provided favorable tumor coverage compared with IMRT or 3DCRT, but RapidArc is not superior to IMRT in terms of liver protection. Further studies are needed to establish treatment outcome differences between the three approaches.

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Most cited references 29

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Intensity-modulated radiation therapy, protons, and the risk of second cancers.

Eric Hall (2006)

Intensity-modulated radiation therapy (IMRT) allows dose to be concentrated in the tumor volume while sparing normal tissues. However, the downside to IMRT is the potential to increase the number of radiation-induced second cancers. The reasons for this potential are more monitor units and, therefore, a larger total-body dose because of leakage radiation and, because IMRT involves more fields, a bigger volume of normal tissue is exposed to lower radiation doses. Intensity-modulated radiation therapy may double the incidence of solid cancers in long-term survivors. This outcome may be acceptable in older patients if balanced by an improvement in local tumor control and reduced acute toxicity. On the other hand, the incidence of second cancers is much higher in children, so that doubling it may not be acceptable. IMRT represents a special case for children for three reasons. First, children are more sensitive to radiation-induced cancer than are adults. Second, radiation scattered from the treatment volume is more important in the small body of the child. Third, the question of genetic susceptibility arises because many childhood cancers involve a germline mutation. The levels of leakage radiation in current Linacs are not inevitable. Leakage can be reduced but at substantial cost. An alternative strategy is to replace X-rays with protons. However, this change is only an advantage if the proton machine employs a pencil scanning beam. Many proton facilities use passive modulation to produce a field of sufficient size, but the use of a scattering foil produces neutrons, which results in an effective dose to the patient higher than that characteristic of IMRT. The benefit of protons is only achieved if a scanning beam is used in which the doses are 10 times lower than with IMRT.

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Transarterial chemoembolization for unresectable hepatocellular carcinoma: meta-analysis of randomized controlled trials.

Pietro Andreone, Calogero Cammà, Ambrogio Orlando … (2002)

To review the available evidence of chemoembolization for unresectable hepatocellular carcinoma (HCC). Computerized bibliographic searches with MEDLINE and CANCERLIT databases from 1980 through 2000 were supplemented with manual searches, with the keywords "hepatocellular carcinoma," "liver cell carcinoma," "randomized controlled trial [RCT]," and "chemoembolization." Studies were included if patients with unresectable HCC were enrolled and if they were RCTs in which chemoembolization was compared with nonactive treatment (five RCTs) or if different transarterial modalities of therapy (13 RCTs) were compared. Data were extracted from each RCT according to the intention-to-treat method. Five of the RCTs with a nonactive treatment arm were combined by using the random-effects model, whereas all 18 RCTs were pooled from meta-regression analysis. Chemoembolization significantly reduced the overall 2-year mortality rate (odds ratio, 0.54; 95% CI: 0.33, 0.89; P =.015) compared with nonactive treatment. Analysis of comparative RCTs helped to predict that overall mortality was significantly lower in patients treated with transarterial embolization (TAE) than in those treated with transarterial chemotherapy (odds ratio, 0.72; 95% CI: 0.53, 0.98; P =.039) and that there is no evidence that transarterial chemoembolization is more effective than TAE (odds ratio, 1.007; 95% CI: 0.79, 1.27; P =.95), which suggests that the addition of an anticancer drug did not improve the therapeutic benefit. In patients with unresectable HCC, chemoembolization significantly improved the overall 2-year survival compared with nonactive treatment, but the magnitude of the benefit is relatively small.

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Volumetric modulated arc therapy for delivery of prostate radiotherapy: comparison with intensity-modulated radiotherapy and three-dimensional conformal radiotherapy.

David Palma, Emily Vollans, Kerry James … (2008)

Volumetric modulated arc therapy (VMAT) is a novel form of intensity-modulated radiotherapy (IMRT) optimization that allows the radiation dose to be delivered in a single gantry rotation of up to 360 degrees , using either a constant dose rate (cdr-VMAT) or variable dose rate (vdr-VMAT) during rotation. The goal of this study was to compare VMAT prostate RT plans with three-dimensional conformal RT (3D-CRT) and IMRT plans. The 3D-CRT, five-field IMRT, cdr-VMAT, and vdr-VMAT RT plans were created for 10 computed tomography data sets from patients undergoing RT for prostate cancer. The parameters evaluated included the doses to organs at risk, equivalent uniform doses, dose homogeneity and conformality, and monitor units required for delivery of a 2-Gy fraction. The IMRT and both VMAT techniques resulted in lower doses to normal critical structures than 3D-CRT plans for nearly all dosimetric endpoints analyzed. The lowest doses to organs at risk and most favorable equivalent uniform doses were achieved with vdr-VMAT, which was significantly better than IMRT for the rectal and femoral head dosimetric endpoints (p < 0.05) and significantly better than cdr-VMAT for most bladder and rectal endpoints (p < 0.05). The vdr-VMAT and cdr-VMAT plans required fewer monitor units than did the IMRT plans (relative reduction of 42% and 38%, respectively; p = 0.005) but more than for the 3D-CRT plans (p = 0.005). The IMRT and VMAT techniques achieved highly conformal treatment plans. The vdr-VMAT technique resulted in more favorable dose distributions than the IMRT or cdr-VMAT techniques, and reduced the monitor units required compared with IMRT.

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Author and article information

Journal

Journal ID (nlm-ta): Radiat Oncol

Title: Radiation Oncology (London, England)

Publisher: BioMed Central

ISSN (Electronic): 1748-717X

Publication date Collection: 2011

Publication date (Electronic): 21 June 2011

Volume: 6

Page: 76

Affiliations

[1 ]Dept. of Biomedical Imaging & Radiological Sciences, National Yang-Ming University, No. 155, Sec. 2, Li-Nong St., Bei-tou, Taipei 11221, Taiwan

[2 ]Dept. of Radiation Oncology, China Medical University Hospital, No. 2, Yuh-Der Rd. Taichung, 404, Taiwan

[3 ]Dept. of Anesthesiology, China Medical University Hospital, No. 2, Yuh-Der Rd. Taichung, 404, Taiwan

[4 ]Dept. of Biomedical Imaging & Radiological Sciences, China Medical University, No. 2, Yuh-Der Rd. Taichung, 404, Taiwan

[5 ]Graduate Institute of Epidemiology, National Taiwan University, 5F, No.17, Hsu-Chow Rd. Taipei, 100, Taiwan

[6 ]Dept. of Radiation Oncology, Wan-Fang Hospital, No. 111, Section 3, Hsing-Long Rd. Taipei, 116, Taiwan

[7 ]Dept. of Radiation Physics, The University of Texas MD Anderson Cancer Center, 1515 Holcombe Bd. Unit No. 94, Houston, TX 77030, USA

Article

Publisher ID: 1748-717X-6-76

DOI: 10.1186/1748-717X-6-76

PMC ID: 3138395

PubMed ID: 21693003

SO-VID: 1a9d2602-0d4f-4de9-a919-a8b4e89569a1

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 cited.

Volumetric intensity-modulated Arc (RapidArc) therapy for primary hepatocellular carcinoma: comparison with intensity-modulated radiotherapy and 3-D conformal radiotherapy

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Abstract

Background

Methods

Results

Conclusions

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Karger: Oncology

Most cited references 29

Intensity-modulated radiation therapy, protons, and the risk of second cancers.

Transarterial chemoembolization for unresectable hepatocellular carcinoma: meta-analysis of randomized controlled trials.

Volumetric modulated arc therapy for delivery of prostate radiotherapy: comparison with intensity-modulated radiotherapy and three-dimensional conformal radiotherapy.

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