The range of conditions which can be treated using kilovoltage X-ray therapy treatment is wide and includes, most commonly, basal cell carcinoma and squamous cell carcinoma. Detailed information concerning treatment of both benign and malignant conditions can be found in the benign and malignant topic section.

In the UK skin cancers are commonly treated using surgery, although superficial radiotherapy treatment is indicated as the treatment of choice for certain patients:

• Elderly patients who would be unsuitable for surgery.
• Patients on anti coagulants where surgery would not be viable.
• Patients presenting with lesions in anatomical sites that would be difficult to surgically excise whilst still maintaining good cosmesis.

As previously discussed in the physics of low energy X-rays topic section, X-rays in the energy range 10kV to 300kV are most suitable for treating skin lesions as they impart most of their energy at the skin surface or a few millimetres below the skin surface. In the clinical setting Kilovoltage therapeutic X-rays are conveniently divided into four areas: 

• Grentz rays; energy range 10-12kV which are commonly used in some centres, particularly in Europe.
• Contact therapy; 50kV range, short source surface distance (SSD) units commonly less than 5cm FSD.
• Superficial therapy; energy range 50-150kV with typical half value layers (HVLs) in the range of 1-8 mm Al.  The FSD is normally 10-30 cm.  The beam characteristics of such X-ray energies are suitable for treatment of lesions up to 5 mm deep, delivering 90% of the dose to the surface.
• Orthovoltage therapy; energy range 150-300kV with FSD of approximately 50cm.  The beam characteristics of such X-ray energies are suitable for treatment of thicker lesions, delivering 90% of the dose within approximately 2 cm of the skin surface.

 

Many different regimes; doses and fraction schedules are used in the UK, this topic section contains information on the author’s preferred treatment regimes, used in the UK.

Malignant Conditions

• Basal cell carcinoma; 40·5Gy given in nine consecutive daily fractions, excluding weekends. Depending on the size and thickness of the lesions, usually 60kV, 100kV or 160kV energy X-rays are mot suitable for these lesions.
• Squamous cell carcinomas; 45Gy given in 10 consecutive daily fractions, excluding weekends. The energy range of X-rays is, again, dependant on the size and thickness of skin lesion to be treated.
• Malignant melanoma; often patients with satellite nodules that may be bleeding are referred for consideration of superficial radiation.  These lesions most commonly present on the extremities especially the ankles and lower limbs. If there is a small cluster of melanoma lesions which can ulcerate and bleed, the author’s choice of treatment is Kilovoltage X-rays in the region of between 60-160kV energy delivering a dose of 20Gy in five fractions. Such treatment is usually very successful for these lesions allowing the patients relief from pain and discomfort.

Benign Conditions

• Haemangioma of the nose, e.g. ala nasi or tip of nose.  These benign vascular tumours respond well to radiation with excellent cosmetic result and the author’s treatment regime is 45Gy in 10 fractions over two weeks at a dose of 4·5Gy per day.  X-rays energies varying between 60 and 160kV are used, depending on the thickness of the haemangioma to be treated.
• Heterotopic bone formation; the author’s experience in treating this condition is usually with a linear accelerator machine. However 300kV energy X-rays can be used, using parallel opposed fields to the hip, delivering a mid point dose of 7Gy. Best results are obtained when the patient receives the radiotherapy treatment a few hours before the operation, e.g. morning radiotherapy, afternoon surgery.
• Peyronie’s disease; the author’s preference for treatment is to enclose the whole shaft of the penis in a plastic shell; three standard sizes available, small, medium and large, including the glans penis.  The total dose delivered using parallel opposed fields to the penis is 12Gy; a total of six treatments, each delivering a  mid-point dose of 2Gy,  treating three times a week over two weeks. Most patients report some benefit within a few months, following treatment, with over 50% of patient reporting a reduction in pain. 

The treatment patients receive is customised to their individual requirements and this may entail close consultation between clinicians, radiographers, mould room technicians and physicists.

Indications for Radiotherapy (RT) [1,2]

• Preferred for lesions that would require reconstructive surgery, where irradiation may be considered to produce better cosmesis, eg nose, upper and lower eyelid (preferably avoid the middle third of the upper eyelid), the lip and lesions involving the commissure of mouth, the nasolabial sulcus, lesions arising in the pre and post auricular areas and the ear.
• Large superficial lesions.
• Older patients.
• Patients who refuse or are unfit for surgery (RT avoids anaesthesia).
• Post surgery- for incomplete/marginal excision, perineural invasion.

Radiotherapy is not normally used in the following circumstances as some skin sites tolerate radiotherapy poorly:

• Sites of previous burns.
• Sites of prior radiotherapy.
• Fragile "tissue-paper" skin after steroids.
• Areas of vascular insufficiency e. Middle third of the upper eyelid.
• The skin of the back overlying the spine (this being an area of skin placed under pressure, leading to compromised healing and late skin necrosis).
• The skin overlying the shin and malleoli of the lower leg (the skin is under tension and there may be impaired healing).
• Patients with ataxia telangiectasia, xeroderma pigmentosa [11].

• Histology/cytology (skin scrape, punch biopsy, excision biopsy).
• Fine needle aspirations of enlarged lymph nodes.
• Imaging in high risk sites to delineate deep extent and bone or cartilage involvement.

• Informed consent is obtained. Patients are treated in a position that best suits the location of the lesion. Immobilisation is achieved as appropriate.
• Generally lesions around the eye, ear, nose and those with an irregular border will require a customised lead cut-out, necessitating a prior mould room appointment. All other areas are treated as ‘mark on set’ using standard lead cutouts to shield the non-target areas using the appropriate thickness of lead.
• The eye requires special protection when eyelids are treated. A lead spatula (if one eyelid involved) or a lead internal eye shield (if both eyelids involved) is inserted under local anaesthetic (LA) to protect the cornea, the lens and uninvolved eyelid (with lead spatula). Patients’ will usually require an eye pad for 2-3 hours after the procedure until the LA effect is reversed & corneal reflex restored. Ensure that patient has an escort, as he/she may not be able to drive back.
• The nasal septum and gum are respectively shielded when lower nose and lip are treated. Wax or aluminium is used to cover the lead shield to absorb electron backscatter.

Tumours are defined according to the gross tumour volume (GTV) which is the visible and demonstratable extent of the tumour and the planned target volume (PTV) which is the GTV plus a margin to allow for inclusion of microscopic disease and set up accuracy [11].

• All patients are examined under a bright light with a magnifying glass, to define the tumour borders.
• Squamous cell carcinoma (SCC); PTV = GTV + 1cm margin all around laterally and a minimum 5mm depth, according to clinician’s discretion.
• Basal cell carcinoma (BCC); PTV = GTV + 0.5cm margin laterally (1 cm if morphoeic, large or poorly defined) and 0.5 cm deep margin. If on mobile skin a 0.25cm deep margin is adequate.
• Clinical photographs are taken for record, clearly indicating the site, extent of lesion and orientation of the photograph.

• Aim to cover PTV with the 90% isodose, both laterally and at depth.
• Low energy photons are used depending on depth, site, size and availability. Avoid electrons near eyes (lateral scatter) and where field sizes are <4cm. Try and avoid treatment with superficial X-rays over cartilage and bone due to risk of radionecrosis (absorption by photoelectric effect). In exceptional circumstances 300kV photons maybe used after discussion with the consultant and senior radiographer.
• Low energy photons (<150kV) deliver almost 100% to the skin and so do not require ‘build-up’.
• The depth dose characteristics of the beam depend on energy and field size.

Prescriptions are defined as applied doses (Dmax) for therapeutic X-ray beams.

Doses depend upon lesion size, histology and patient characteristics.

Basal Cell Carcinoma - prescribed doses:

Squamous Cell Carcinoma - prescribed doses:

For new patients it is necessary for the clinician to see set-up on the treatment unit for the first fraction for a ‘mark on set’. Where customised lead cut-outs are used it is not essential for a clinician to be present, however, it is the responsibility of the senior radiographer to ensure that the mould room cut-out matches the marked on field as per the clinical mould room photograph. If there are any concerns the clinician should be consulted. Decisions regarding stand off correction (inverse square law) should be made as required.

Patients are usually seen in clinic weekly during the course of their treatment during longer fractionation schedules and at least once during shorter fractionations. Skin care advice is given as for all superficial radiotherapy. Post treatment follow up should be arranged for 4-6 weeks and thereafter at the clinicians’ discretion.

This is also known as squamous cell carcinoma in situ and is generally treated by dermatologists. Cases may be referred for radiotherapy when non-responsive areas become troublesome to the patient and are associated with thickening, pain and bleeding. Guidelines from the British Dermatology Association suggest that Bowens disease of the lower limb does not have to be treated and can be observed.

Dose
Treated as a squamous cell carcinoma to a dose of 45Gy in 10# over 2 weeks.

As many of these patients are young, and will live long enough to experience potential late radiation toxicity, this must be discussed specifically when obtaining signed consent. The information given must be recorded in the case notes. No patients under 16 years old will be consented without the presence of a parent or guardian. It is advisable to involve the paediatric radiotherapy consultant when considering treatment for younger patients.

These patients are treated jointly with the plastic surgery team. Radiotherapy is given to the operative site within 24 hours after operation. (In exceptional cases 48 hours may be permitted). This requires close liaison: if there are no free treatment spaces within 24 hours of the suggested operation time, inform the surgeons at once, so that operation dates can be altered.

Technique

Direct low voltage photon irradiation is used. The PTV is the whole operative scar including suture sites, with 0.5cm margin and is treated with 60kV photons. If the scar extends to both sides of the earlobe target volume is treated with 160kV photons with additional lead shielding for exit dose.

Please remember that the treatment volume will need to be greater, due to fall-off in dose at field edges. This effect is more pronounced in long, narrow fields. Ask advice from physics if you are unsure what extra margins to allow in positioning the lead shielding.

All keloid scars are treated as ‘mark on set’. 2mm lead shielding is required to protect skin in non-target areas.

Dose

10Gy in one single fraction (applied dose).

Patient Review

It is necessary for a clinician to be present at time of treatment to see the set up and correct for stand off. Patients are reviewed in clinic 6-8 weeks later and then discharged after a clinical photograph. Patients are not routinely followed but are advised to return to the radiotherapy clinic if they are concerned about recurrence.

Irradiation for Recurrent Keloid after Intial Surgery and Radiotherapy

In principle, this protocol should only be used after careful discussion with the consultant. It is always preferable to treat keloids after complete excision by plastic surgery teams. In all other cases of established keloid scars please discuss with the consultant if patient is not going to have surgery for any reason.

Technique

Direct low voltage irradiation is used. The PTV is the whole keloid, with 3 - 5mm lateral margins. The energy used and focal skin distance chosen, is designed to encompass the maximum depth of the keloid within the 80% isodose of the treatment. For thin lesions, this will typically be 60 or 100Kv photons. 2mm lead shielding is required to protect skin in non-target areas.

Dose

Dose 16Gy in 4# over 12 months or 16Gy in 4# over 4 months.

Long duration protocols are used in young patients. This policy of extended treatment allows for patients who have made a good response following one or two treatments, not to continue and therefore to avoid unnecessary radiation dose. Patients must be reviewed prior to each fraction and set up seen by a clinician.

For small localised plaques and tumours, treatment with low energy photons are adequate. PTV = GTV + 0.5 to 1 cm margins; margins tend to be smaller as these patients are often retreated.

Dose: 8Gy in 2# or 12Gy in 3#, treating daily

For a larger or thicker tumour or collection of plaques, and particularly if the area is over a joint consider treatment with electrons.

Dose: 20Gy in 5# over 1 week or 30Gy in 10# over 2 weeks.

Cutaneous angiosarcoma is a rare and aggressive endothelial-derived sarcoma usually affecting the elderly. Combined modality approach is often required including surgery, radiotherapy and chemotherapy.

Technique

Photons are used as appropriate. A customised cut out maybe required. A margin of at least 1 cm is required as sub microscopic disease can extend beyond clinical tumour margin.

Dose: 55Gy in 20# over 4 weeks or 60Gy in 30# over 6 weeks.

PCBCL is an indolent form of lymphoma with a good prognosis. Although local cutaneous recurrences are observed in 25% to 68% of patients, dissemination to internal organs is rare. 5-year survival rates typically range from 89% to 96%. Overly aggressive treatment of PCBCL has not been shown to improve survival or prevent relapse. Radiation therapy is the treatment of choice for localized disease at presentation or on relapse. Polychemotherapy should be reserved for involvement of noncontiguous anatomic sites or those with extracutaneous spread.

EORTC classification of PCBCL:

Once the diagnosis of PCBCL is established, history, physical examination & staging investigations should be performed to rule out systemic involvement.

Technique: Photons or electrons as appropriate. PTV= GTV+ 2-3 cm margin.

Dose: 15Gy in 5# over 1 week or 20Gy in 5 #.

This is a non-invasive melanotic lesion generally occurring on the face. Treatment with radiotherapy is preferred in areas of cosmetic and functional importance and this can achieve local control. Although this is generally a flat lesion it has irregular borders with varying degrees of pigmentation and a customised cut out is usually required. Planning target volume= GTV + 1cm margin laterally and 0.5 cm deep margin.

Dose: 45Gy in 10# over 2 weeks with 60 kV - 160 kV photons.

As the metastatic presentation of this disease can be myriad the treatment should be individualised to suit the patient and the treatment regimen should be discussed with the consultant. Treatment intent is palliative. Some commonly used schedules for cutaneous disease include the following:

Dose

• 30-36Gy, 6Gy per # once weekly over 5-6 weeks.
• 20Gy in 5# over 1 week.
• 30Gy in 5#, 2# given each week.
• 8-10Gy in 1# especially in poor performance status patients where rapid control of symptoms such as bleeding is required.

These are rare neuroendocrine tumours arising from the mechanoreceptors of the basal epidermis that are particularly aggressive with a propensity for head and neck and the extremities. Causative factors include exposure to sunlight and immunosuppression. The tumour has many similarities to small cell carcinoma of the lung, with intrinsic sensitivity to radiotherapy and chemotherapy and an aggressive metastatic potential.

Staging

• IA Disease confined to skin and <2 cm in diameter.
• IB Disease confined to skin and >2 cm in diameter.
• II Involvement of regional lymph nodes.
• III Metastatic disease.

Treatment

Surgery is the initial treatment of choice. Most groups advocate a 2–3-cm tumour-free margin around the primary lesion when technically possible (no controlled trials comparing different margins), but this is often difficult to achieve in the head and neck region. Many authors recommend postoperative radiotherapy on the basis of retrospective comparison of patients treated with surgery alone with those treated with surgery and post operative radiotherapy 8,9. The addition of radiotherapy reduced the local failure from 39% to 26% and the regional failure from 46% to 22%. Radiation volumes have included the GTV with generous margins to ensure that the dermal lymphatics surrounding the primary are treated to full dose. The doses used have varied from 45–60Gy, with higher doses being applied to areas of bulky disease.

Treatment of regional draining lymph nodes has been recommended, although prophylactic node dissection or radiotherapy has not shown to influence overall survival. Sentinel node biopsy has been proposed to identify risk of recurrence and minimise need for node dissection.

The presence of distant metastases carries a grave outlook, with median survival being only 9 months. Treatment intent is purely palliative. Radiation can be used to palliate bone and brain secondaries and for advanced cutaneous deposits that are bleeding or fungating.

The role of adjuvant chemotherapy remains undefined. Overall response rates to combination chemotherapy (usually platinum based) for surgically unresectable distant metastatic disease are generally high, although responses are transient.

Technique

Radical: Photons are used depending on depth, site and size of lesion to be treated. PTV=GTV + 3-5cm.

Dose:

Radical: 45-60Gy over 5-6 weeks (higher doses for residual or bulky disease).

Palliative: 20Gy in 5# over 1 week.