Generally local recurrences after surgical resection of a melanoma with adequate margins is less than 5%. Some lesions have a higher risk of local relapse (see table below) and if more aggressive surgery is not a choice then postOp radiation may be useful. Similarly in high risk  nodal patients postOp XRT has cut the local relapse rate down from 30 - 80% range to 6 - 20% range see tables.) Also in patients who do not have a sentinel node biopsy but are at high risk for having positive nodes, there may be a role for elective nodal irradiation (see tables below) And patients who have a + sentinel node but do not have the rest of the nodes resected the risk that they have additional + nodes is 18% (7 - 36%) so radiation to these nodes instead of surgery is an option

Local Recurrence Rates after Surgery Alone for High Risk Lesions

Characteristic	Relapse Rate
Breslow thickness > 4mm	6 - 14%
Head & Neck Site	5 - 17%
Ulcerations	10 - 17%
Satellitosis	14 - 16%
Desmoplastic histology	23 - 48%

Indications for PostOp Radiation to Primary Site  from Ballo
(Oncology 2004;18:99)

desmoplastic melanoma positive margins locally recurrent disease Breslow > 4mm and ulceration Breslow > 4mm and satellitosis

Regional Recurrences after Surgery Alone for Nodal Disease

Characteristic	Relapse Rate
extracapsular extension	31 - 63%
4 or more + nodes	22 - 63%
Nodes 3cm or larger	42 - 80%
Cervical node location	33 - 50%
Therapeutic dissection	20 - 50%

    

Indications for PostOp Nodal Irradiation

extracapsular extension 4 or more + nodes nodes 3cm or larger cervical node location recurrent nodal disease sentinel node involved but complete node dissection not planned

Risk of Positive Sentinel Node by Primary Tumor Thickness

Thickness	Positive Node Rate
0 - 0.75mm	1%
0.76 - 1.5mm	7%
1.51 - 4mm	21%
> 4mm	33%

Indications for Elective Nodal Irradiation

Clarke Level IV or higher Breslow Thickness 1.5mm or thicker

The standard technique from MD Anderson if 30 Gy (600cGy X 5 fractions) over 2.5 weeks (Mon/Thurs or Tues/Friday) but limit the brain, spinal cord or small bowel to 24Gy. The margins around the primary are 2-4 cm, and the nodes included are shown in the diagrams below, and for inguinal nodes they do not try to include subclinical nodes (e.g. external or common iliac.)

radiation portal for axillary metastases to include low cervical, supraclavicular and level I, II, III		radiation portal for cutaneous head and neck to include draining lymphatics