Radiotherapy in patients with lung cancer involves the use of various methods of dose administration. The standard method of radiation therapy consists in conducting radiation from two direct opposite curly fields — the anterior and posterior, or — with the anterior straight and posterior paravertebral (from the tumor in the lung) located at an angle of 20-30 degrees to the sagittal plane.
With self-radiation treatment, the dose fractionation technique is used: 4 Gy three times, then 2 Gy daily 5 times a week to a total dose of 30 Gy. This course is repeated after 10— days. It is believed that various radiobiological effects occur in the tumor tissue, including more pronounced damage to its parenchyma, especially in the most well-oxygenated sites, as well as accelerating the reoxygenation of the hypoxic zones of the parenchyma with increasing their radiosensitivity.
When choosing the amount of radiation in patients with lung cancer, take into account the goal of radiation therapy — radical or palliative, type of treatment — independent or in combination with a surgical operation, the histological structure of the tumor.
In patients with non-small cell lung cancer, the formation of curly fields is carried out, through which the primary tumor, intrapulmonary, root (on the affected side), mediastinal lymph nodes on both sides (paratracheal, tracheobronchial, bifurcation, pre-ortho-rototic) are irradiated, regardless of the presence or absence of metastases.
In peripheral lung cancer, two areas are usually planned for irradiation: the tumor itself, located at a distance from the root elements, and regional collectors in the mediastinum. Water from the irradiation zones includes the so-called “path” to the root of the lung.
When forming fields for preoperative radiation therapy in patients with the location of the tumor in the upper lobes of the lung, their lower boundary at the level of the root of the affected lung is determined by the location of the mouth of the corresponding lower lobe bronchus. In patients with tumor localization in the middle or lower lobes, the upper limit of the irradiation field is oriented according to the location of the initial section of the upper lobe bronchus of the affected lung.
After applying a dose of 45— Gy, it is advisable to re-form and refine the fields — in order to reduce the amount of radiation from tissues not involved in the blastomatous process.
When planning palliative radiation therapy, only the areas of reliably verified spread of lung cancer are included in the amount of radiation.
On entering radiation treatment, hematological indicators are monitored and local radiation reactions are evaluated and corrected. The most frequent complications are radiation pneumonitis, esophagitis, endobronchitis. During irradiation, tumor disintegration, hemoptysis, which will require not only a reduction in doses and volumes, may become limiting factors.
exposure, but also its termination. In the process of radiotherapy, doses to the spinal cord should not be exceeded.
brain and heart, due to the development of irreversible changes in them. Contraindications for radiotherapy of lung cancer are associated with common
the condition of patients, especially those who have undergone advanced combined resection of the lung, with the prevalence of the tumor process and associated diseases. The latter may be associated with the actual tumor growth, and paracancotic changes in the lung and pleural cavity.
Radiation therapy is contraindicated in patients with severe cardiovascular, renal and hepatic failure, active pulmonary tuberculosis, decompensated diabetes, as well as with various mental disorders. The reason to refrain from radiation treatment is hemoptysis with a tendency to pulmonary hemorrhage, the formation of cavities of decay, the appearance of pronounced pleurisy, as well as a significant reduction in hematological parameters: anemia, leukopenia, thrombocytopenia.
In cases of continued tumor growth or the diagnosis of true recurrence, re-irradiation of patients is possible. This takes into account the time elapsed after the end of the previous course of radiation therapy, as well as its volume. In these cases, only the site of tumor recurrence is usually irradiated in the normal fractionation mode, bringing the total focal dose to 40— Gy.
When distant hematogenous metastases appear, they can be irradiated. Thus, in case of metastasis of lung cancer to the brain, its entire volume is irradiated with ocular screening or more precisely, taking into account the exact location of the metastasis. Similarly, it is possible to conduct irradiation of the liver. Spinal metastases are irradiated according to standard methods or in non-traditional modes in order to relieve pain faster and reduce the number of fractions. In these cases, the total dose plan individually.