In general, patients over the age of 60 with moderately to larger-sized tumours in the facial region can be treated with radiotherapy (RT) when the expected outcome is better than with alternative methods [4]. Locations like the eyelids (Fig. 27.2), nose (Fig. 27.3), lips and ears produce particularly satisfactory results, both cosmetically and functionally. It is likewise an excellent option for patients receiving anticoagulants [4].

The half-value depth in tissue (HVD) must always correspond to the approximate thickness of the tumour. This usually results in optimum protection of the skin lying underneath, while simultaneously destroying the tumour. When suspecting the presence of possible invasive tumours, a magnetic resonance imaging (MRI) is required prior to therapy as tumours that have infiltrated cartilage or bone are not an indication including soft X-ray and surface therapy.

Radiation treatment is only carried out after a histopathological examination. The histology provides information not only on the type and extent of the tumour but also on potential special histological subtypes, such as sclerodermiform growth patterns in basal cell carcinomas [5]. The latter are less sensitive to radiation – probably due to the concomitant fibrosis – and often exhibit a tendency to relapses, partly due to the difficulties in clinical delimitation. However, this does not necessarily mean that radiation therapy must be excluded as an option for inoperable patients. The radiation parameters should, however, be adapted, for example, through higher individual doses or higher total doses or through treatment with faster electrons. As a rule, basal cell carcinomas (BCCs) and squamous cell carcinomas (SCCs) can be treated in the same way. There is a general tendency towards using higher total doses for SCCs. Local control rates in BCCs range from 90 to 95 % [4], and careful patient selection can result in even higher cure rates [6–8]. In a prospective trial, where 93 patients with BCC were randomised to receive either cryosurgery or radiation therapy, the 2-year cure rate for the RT group was 96 % [9]. Cosmesis is rated in over 90 % as excellent or good [6]. Most important long-term side effects (after 4 years) are hypopigmentation and telangiectases in 92 and 82 %, respectively [10] (Fig. 27.4). Factors influencing cosmetic results are in order of importance: time after treatment, site, tumour thickness, field size and treatment parameters [10, 11].

The risk of radiation-induced malignancy is probably lower than 1:1,000 after 10–15 years [12]. Radiotherapy can be used to treat many types of BCC, even those overlying bone and cartilage, although it is probably less suitable for the treatment of large tumours in critical sites, as very large BCC masses are often both resistant and require radiation doses that closely approach tissue tolerance.

Local control rate is lower for SCC by 10–15 % than an equivalent-sized BCC [13]. Poorly differentiated SCCs recur in up to 50 % and therefore should not be treated with X-rays [1]. For high-risk SCCs, Mohs surgery should be preferred [14].

In special circumstances – especially in larger SCCs on the lower lip – brachytherapy may be used alternatively. In these cases a radiation source is placed inside or next the tumor area. For example Cobalt-60 can be used to generate gamma rays, produced by spontaneous decay of the nucleus.

Electron beam therapy – where electrons are directed to a tumor site – is produced by a linear accelerator. An electron beam will penetrate to a certain depth and spare any underlying tissue from radiation damage. Therefore this form of radiation is best used to irradiate large skin cancers in sites overlying cartilage or bone.