Radiat Oncol J.  2016 Jun;34(2):145-155. 10.3857/roj.2015.01592.

Dosimetric comparison of axilla and groin radiotherapy techniques for high-risk and locally advanced skin cancer

• Mattes MD
• Zhou Y
• Berry SL
• Barker CA

• KMID: 2327388
• DOI: http://doi.org/10.3857/roj.2015.01592

Abstract

PURPOSE
Radiation therapy targeting axilla and groin lymph nodes improves regional disease control in locally advanced and high-risk skin cancers. However, trials generally used conventional two-dimensional radiotherapy (2D-RT), contributing towards relatively high rates of side effects from treatment. The goal of this study is to determine if three-dimensional conformal radiation therapy (3D-CRT), intensity-modulated radiation therapy (IMRT), or volumetric-modulated arc therapy (VMAT) may improve radiation delivery to the target while avoiding organs at risk in the clinical context of skin cancer regional nodal irradiation.
MATERIALS AND METHODS
Twenty patients with locally advanced/high-risk skin cancers underwent computed tomography simulation. The relevant axilla or groin planning target volumes and organs at risk were delineated using standard definitions. Paired t-tests were used to compare the mean values of several dose-volumetric parameters for each of the 4 techniques.
RESULTS
In the axilla, the largest improvement for 3D-CRT compared to 2D-RT was for homogeneity index (13.9 vs. 54.3), at the expense of higher lung Vâ‚‚â‚€ (28.0% vs. 12.6%). In the groin, the largest improvements for 3D-CRT compared to 2D-RT were for anorectum Dmax (13.6 vs. 38.9 Gy), bowel D200cc (7.3 vs. 23.1 Gy), femur Dâ‚…â‚€ (34.6 vs. 57.2 Gy), and genitalia Dmax (37.6 vs. 51.1 Gy). IMRT had further improvements compared to 3D-CRT for humerus Dmean (16.9 vs. 22.4 Gy), brachial plexus Dâ‚… (57.4 vs. 61.3 Gy), bladder Dâ‚… (26.8 vs. 36.5 Gy), and femur Dâ‚…â‚€ (18.7 vs. 34.6 Gy). Fewer differences were observed between IMRT and VMAT.
CONCLUSION
Compared to 2D-RT and 3D-CRT, IMRT and VMAT had dosimetric advantages in the treatment of nodal regions of skin cancer patients.

Keyword

Intensity-modulated radiotherapy; Skin neoplasm; Conformal radiotherapy; Merkel cell carcinoma; Melanoma; Squamous cell carcinoma

MeSH Terms

Axilla*
Brachial Plexus
Carcinoma, Merkel Cell
Carcinoma, Squamous Cell
Femur
Genitalia
Groin*
Humans
Humerus
Lung
Lymph Nodes
Melanoma
Organs at Risk
Radiotherapy*
Radiotherapy, Conformal
Radiotherapy, Intensity-Modulated
Skin Neoplasms*
Skin*
Urinary Bladder