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Radiation treatment for locoregional recurrence and distant metastases from malignant melanoma


Medical editor Kari Dolven-Jacobsen MD Ph.D.
Oncologist

Oslo University Hospital
Norway

General

Radiation treatment provides good palliation in up to 50% of patients (1).

Indications

Radiation treatment should be considered:

  • Postoperatively, for example after resection of local relapse, and after bone and brain metastasis surgery where there is uncertainty of radicality, and where reoperation is not appropriate. For repeated locoregional relapse despite adequate surgery, or for repeated local relapse. 
  • For repeated locoregional relapse despite adequate surgery, or for repeated local relapse.
  • In some cases after lymph node dissection. Studies suggest that patients operated for metastases in the neck may benefit from postoperative irradiation, especially after perinodal growth (39). When the resection margins are not free after lymph node dissection of the axilla or groin postoperative irradiation should also be considered.
  • For painful, bleeding, or cosmetically problematic metastases, skin or subcutaneous, metastases where surgical or electrochemotherapy is not an option irradiation should be performed before the tumor volume is too large and before the tumor ulcerates. Cutaneous and subcutaneous metastases can be treated with electrons without any substantial problems for the patient. Such lesions respond often well to this kind of treatment.
  • For bone metastases causing pain or possibility of fracture. Additional surgical treatment should also be considered when fracture is feared. 
  • For metastases which compromise or threaten vital structures such as the spinal cord, nerve roots, and central airways possibly combined with surgery.
  • For brain metastases. In case of brain metastases (with other metastases under control) radiotherapy towards total brain should be considered, possibly supplied with a boost towards the tumor area. Stereotactic irradiation should be considered in case of 1-4 metastases. Transient control will be seen in 80-90 % of the patients (2).
  • Stereotactic treatment may be given in some cases towards catastases in circumscribed areas in other organs like lung, liver, spleen and the adrenals, often with good result. Stereotactic irradiation can also be given towards 1-3 metastases in the vertebral column when these are not located imidiately near the spinal canal (30). Such treatment enhances the possibility of tumor control, rapid clinical response and a more prolonged effect. Reirradiation is possible due to a reduced dosage towards the spinal cord.

Goal

  • Palliation

Definitions

Target volume

 

 

Target volume definitions from ICRU
(International Commission on Radiation Units and Measurements)

GTV (= Gross Tumor Volume)

Tumor volume

Palpable or visible/identifiable area of malignant growth.

CTV (= Clinical Target Volume)

Clinical target volume

Tissue volume which contains GTV and/or subclinical microscopic malignant disease.

ITV (= Internal Target Volume)

Target volume

Volume containing CTV and one inner margin taking into account inner movements and revisions of CTV. 

PTV (= Planning Target Volume)

Planning volume

Geometric volume containing ITV and one set-up margin taking into account variation in patient movement, patient positioning, and field modeling.


Preparation

A CT dosage plan is usually performed as a preparation for all radiation treatment. For stereotactic irradiation towards brain metastases MR of the brain is performed additionally. When cutaneous metastases is being treated with electrons, the field set-up is often marked directly on the patient`s skin.

During CT dose planning it is important that the patient is optimally treated for pain and is able to remain still in a supine position. Premedication may be given. Extra dose of opiated may also be necessary.

Before the first radiation treatment to the brain, a customized plastic mask is made for the head to immobilize the patient.


Implementation

The radiation treatment can often be carried out on an outpatient basis with weekly doctor visits. Individual factors may suggest deviation from standard treatment. These factors may be: 

  • general status 
  • risk of bleeding
  • the location of the lesion

Standard treatment

  • 3 Gy x 10, or 4 Gy x 5. 
  • 2.5 Gy up to 50 Gy, postoperative with a curative intention. 
  • 8 Gy x 1 to bone metastases.

Total brain

  • If the patient's other metastases are under control, 3 Gy x 10 to the entire brain can be administered.

Stereotactic irradiation (at Oslo University Hospital):

  • Brain metastases: 18-25 Gy x 1 depending on the diameter of the tumor.
  • Lung metastases: 15 Gy x 3 for peripherally located tumours, 7Gy x 8 for tumors at the Hilum/mediastinum.
  • Metastases in the liver, spleen, adrenals: 3 fractions 10-15 Gy depending on size and location of the tumor.
  • Vertebral column: 24 Gy x 1.

Many patients may require dexamethasone treatment during radiation treatment to the brain, or while waiting for the radiation treatment and possibly for some time after the treatment.

Irradiation combined with systemic treatment

  • BRAF inhibitors: Patients treated with BRAF inhibitors (Zelboraf®, Tafinlar®) must discontinue the treatment for around 1 week before, during and 1 week after the irradiation to avoid serious side-effects, especially from the skin.
  • Immunotherapy: Patients given Ipilimumab or PD-1 inhibitor may receive irradiation between 2 courses.
  • Chemotherapy: Patiens on DTIC or other chemotherapy may receive irradiation between 2 courses.

Follow-up

All patients have their first follow-up at their local hospital or at Oslo University Hospital 4-8 weeks after end of treatment for evaluation of treatment result, side effects, and need for other treatment.

Subsequently, the patient attends a routine follow-up schedule.

Side effects

Possible side effects may be:

  • fatigue
  • skin soreness 
  • soreness in the throat
  • diarrhea, depending on area treated

The radiated area must be protected from sun exposure during the first years after treatment since the skin can be easily sunburned.


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