Palliative radiation therapy of lung cancerMedical editor Odd Terje Brustugun MD
Oslo University Hospital
Palliative radiation therapy is a useful first-choice treatment in patients with non-small cell lung carcinoma in stages III and IV, where a positive effect from systemic chemotherapy is unlikely.
Symptoms in patients with small cell lung carcinoma are usually effectively relieved by chemotherapy. Patients with recurrence of small cell lung carcinoma, where additional chemotherapy is not considered beneficial, may obtain successful palliative results from radiation therapy.
Locally advanced lung cancer may cause many different symptoms. Palliative radiation therapy is a relatively mild treatment and the majority of the patients are relieved of bothersome symptoms by this treatment.
Subjective improvement reported by patients
|Vena cava superior syndrome
Palliative radiation therapy is often given in fractions that optimize the therapeutic effect while minimizing unwanted side effects and with short treatment time. In this way, a high total dose is given to the tumor tissue while damage to the normal tissue is minimized.
When the treatment is given as palliation it is very important that the acute side effects are insignificant and of short duration.
Palliative radiation therapy is used for primary tumors, local recurrence, and metastasis.
- Incurable lung cancer
- Symptomatic metastases
- Relieve symptoms
- Prevent new symptoms
The tumor, including pathologically enlarged lymph nodes in the ipsilateral hilum and mediastinum define the target volume (GTV). Margins of 1.5–2 cm are used to compensate for microscopic spreading, tumor movement with respiration, and tuning variations (CTV, ITV and PTV). The volume of risk organs in the radiation field such as the medulla, heart, and healthy lung, must be minimized according to the maximum tolerable dosage. Asymptomatic parts of the tumors are not included if the field gets too big. Maximum field size should as a rule of thumb not exceed 200 cm2.
|Target volume definitions from ICRU
(International Commission on Radiation Units and Measurements)
GTV (= Gross Tumor Volume)
|Palpable or visible/demonstrative area of malignant growth.
CTV (= Clinical Target Volume)
Clinical target volume
Tissue volume which contains GTV and/or subclinical microscopic malignancy.
ITV (= Internal Target Volume)
Volume containing CTV and one inner margin taking into account inner movements and revisions of CTV.
PTV (= Planning Target Volume)
Geometric volume containing ITV and one Setup margin taking into account assumed variations for patient movements, variations in patient arrangement, and field modeling.
Target volume and radiation technique
The radiation fields are formed based on the CT images .
- The patient meets for imaging on a dedicated CT machine, with or without contrast.
- The localization of the tumor and risk areas are drawn directly into the images to create a 3D radiation volume.
- Radiation therapists suggests a radiation field set-up which is eventually adjusted and approved by a medical physicist and the treating doctor. Ideally, there should be a uniform dose distribution over the target volume and no radiation to critical organs. In reality, this is impossible to achieve. The dose distribution is therefore a compromise between what is desired and what is possible.
- At the CT imaging session, it is very important that the patient is well medicated for pain and is able to lie still in a supine position when the images are taken. If necessary, pain-releiving premedication is given.
- The patient lies flat on a bench with only a thin mattress.
It is very important that the patient is well medicated for pain and is able to lie still.
8.5 Gy x 2
All patients in Norway with metastatic disease are normally given hypofractionated treatment of 8.5 Gy x 2, if radiation towards the central airways is necessary.
This applies to patients with:
- stage IV cancer
- stage III (A and B) cancer and poor prognostic factors
- a large tumor (diameter > 9-10 cm)
- reduced general health (WHO PS > 2)
- significant weight loss (> 5-10% in the last 3 months)
The patient will receive steroids the day before treatment, day of treatment, and day after treatment to reduce side effects.
3 Gy x 10-13
This fractionation scheme is given for both small cell and non-small cell lung carcinoma. The number of fractions depends on the extent of the disease. By 13 treatments, the field composition must be tuned in order to adjust the dose to the spinal cord. The total treatment time is 2-3 weeks with one daily treatment, 5 days per week.
Pancoast tumor 3 Gy x 13
Pancoast tumors are non-small cell lung carcinomas in the superior sulcus which often have rib or nerve involvement. These tumors often cause significant pain and the patient often survives longer than for other tumor localizations. The total treatment time is 2-3 weeks with one treatment every day for 5 days per week. In some cases, additional 2-3 treatments to the primary tumor may be necessary.
Pancoast tumors without lymph node involvement, which are initially inoperable, may in some cases be given neoadjuvant chemoradiotherapy (2 Gy x 25 with concomitant platinum-based chemotherapy) and subsequently evaluated for surgery.
Endocavitary radiation therapy (brachytherapy)
For local recurrence in the central airways, radiation can be given endobronchially. Brachytherapy is usually used for recurrence which causes symptoms in previously irradiated patients. This treatment is sometimes combined with laser coagulation and stenting.
Radiation therapy to metastasis
Lung cancer frequently metastasizes, especially to other parts of the lungs, skeleton, and brain. Palliative radiation treatment to skeletal and soft tissue metastases provides symptom relief. Pain from skeletal metastasis can be relieved in 60-80% of the patients. Single fractions of 8–10 Gy provides a satisfactory effect. For larger soft tissue components and also for weight-carrying bones with fracture risk, it may be appropriate to provide fractionated treatment such as 3 Gy x10. Symptomatic brain metastases are often relieved by radiation. Liver metastases are rarely treated with radiation but this may be appropriate when there is resistance to chemotherapy or they are symptomatic. Stereotactic radiation with one (against brain/columna metastases) or three (extracranial metastases) fractions may be appropriate in the presence of a single or few metastases (oligometastases).
Most of the side effects occurring during treatment arise from healthy organs included in the radiation field. The dose levels used for pure symptom relief are kept low to minimize the risk of acute side effects.
The total dose is at a level which renders the risk for delayed reactions low.
Good follow-up care is important to achieve satisfactory relief of symptoms and usually takes place locally at the referring hospital or primary care doctor.
Radiation therapy may render the patient more fatigued and lethargic. Reduced appetite, nausea, diarrhea, and pain cause fatigue. The fatigue does not always go away when treatment is over.
Reactions in the skin from radiation are normal and worsen with increasing doses. Soreness may last and/or increase until at least a couple of weeks after treatment is finished. Intertriginous areas (for example under the breasts) are especially susceptible. Airing, application of salt water compresses and perfume-free creams may help. Salves and creams should not be applied to the radiation field in the last hours before each treatment session.
Radiation treatment which includes larger or smaller parts of the mediastinum and neck, leads to irritation and soreness in the throat and esophagus, which leads to problems swallowing. Lubricating with cream or ice cream right before eating may help, otherwise local analgesics or systemic pain medication will help. In rare cases, tube feeding is necessary.
Swelling in the radiated tissue/mucosa can lead to temporary worsening of breathing difficulty after the first treatments. Radiation-induced lung inflammation (pneumonitis) with or without fever can also occur, and may be treated with steroids.
A delayed reaction to radiation treatment to the lungs is reduced lung capacity.