Adjuvant hypofractionated intensity modulated radiation therapy after resection of regional lymph node metastases in patients with cutaneous malignant melanoma of the head and neck

The Role of Particle Therapy in Adenoid Cystic Carcinoma and Mucosal Melanoma of the Head and Neck

Particle irradiation is suitable for resistant histologies owing to a combination of improved dose delivery with potential radiobiologic advantages in high linear energy transfer radiation. Within the head and neck, adenoid cystic carcinoma and mucosal melanoma are two such histologies, being radioresistant and lying closely proximal to critical structures. Here, we review the use of particle irradiation for adenoid cystic carcinoma and mucosal melanoma of the head and neck.

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

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 V₂₀ (28.0% vs. 12.6%). In the groin, the largest improvements for 3D-CRT compared to 2D-RT were for anorectum D_max (13.6 vs. 38.9 Gy), bowel D_200cc (7.3 vs. 23.1 Gy), femur D₅₀ (34.6 vs. 57.2 Gy), and genitalia D_max (37.6 vs. 51.1 Gy). IMRT had further improvements compared to 3D-CRT for humerus D_mean (16.9 vs. 22.4 Gy), brachial plexus D₅ (57.4 vs. 61.3 Gy), bladder D₅ (26.8 vs. 36.5 Gy), and femur D₅₀ (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.

[Malignant head and neck melanoma: Part 2: Therapy]

Resection margins of melanomas in the head and neck region often have to be adapted according anatomical circumstances. In the case of thicker primary tumors or after complete resection of locoregional lymph node metastases, adjuvant therapy with interferon-α can be performed; in some cases, adjuvant radiotherapy may also be indicated. In the case of inoperable lymph node or distant metastases, systemic treatment is required. Beside well-established mono- or polychemotherapy regimens, newer targeted therapies with BRAF inhibitors (vemurafenib, dabrafenib), mitogenic-activated protein kinase (MEK) inhibitors (trametinib, binimetinib, and cobimetinib), and kinase inhibitors (imatinib, sunitinib, nilotinib, dasatinib) are also available.