radiation for skin cancer

Radiation therapy is an important management option in selected non-melanoma skin cancer patients, offering an advantage in treating large lesions with deep tissue infiltration, and alone or combined with surgery for tumors along embryonic fusion planes. Treatment margins may be as wide as necessary for facial tumors, obviating the need for extensive surgical reconstruction. Radiation may be preferred for elderly, debilitated, or medically inoperable patients as anesthesia is not necessary, and when cosmesis is not a factor, fractionation can minimize the number of treatments.

Skin cancers with perineural invasion are particularly difficult to control, and salvage after surgical recurrence is unlikely. In reported series, asymptomatic patients with microscopic, incidental, perineural invasion receiving postoperative irradiation had 78% local control versus 50% for patients with neurologic symptoms or gross perineural extension. Magnetic resonance imaging (MRI) documents gross perineural spread and facilitates radiation planning. Treatment fields encompass the nerve at risk to the base of skull with postoperative radiation to 60 Gy to the tumor bed, 50 Gy to the proximal involved nerve with negative surgical margins, and 66 to 70 Gy for microscopic or gross positive margins.

Radiation fields can encompass multiple lesions or regional nodes. Although lymph node metastases are rare for BCC, they are seen in 5% to 10% of cutaneous SCC. Parotid area nodes, most commonly involved for cancers of the face, scalp, and ear, are particularly suited to treatment with radiation as definitive management or after surgical resection with prophylactic treatment of the ipsilateral neck.

Radiation therapy may be contraindicated in young patients because of potential carcinogenesis and tendency toward cosmetic deterioration over time. Contrary to early reports that involvement of bone or cartilage is a contraindication to radiation therapy, excellent control rates with good cosmesis, function preservation, and rare complications are achieved with modern techniques and equipment.

Postoperative radiation therapy may be employed after incomplete surgical resection. Although the 10-year actuarial probability of local control is excellent for patients with BCC treated either immediately after surgery for positive margins (92%) or at time of recurrence (90%), this is not true for patients with SCC in whom local control and survival are improved when they receive radiation immediately after incomplete excision. Perez found 87% tumor control and 10% to 15% nodal metastases in initially treated patients versus 65% tumor control and 39% nodal metastases in patients treated for salvage.