Lung metastases are secondary neoplasms that have arisen during the migration of malignant cells from another organ. At the initial stage, symptoms of general intoxication and recurrent colds are manifested. Subsequently, shortness of breath, chest pain and cough with an admixture of blood appear. The diagnosis is made taking into account clinical manifestations, X-ray data, chest CT, histological and cytological studies. Treatment – chemotherapy, radiotherapy, laser resection, radiosurgery and traditional surgical interventions.
General information
Lung metastases are secondary malignant foci in the lung tissue. A lymphogenic, hematogenic or implantation pathway of cell migration from a neoplasm located in another organ is possible. They are one of the most common secondary tumors. Men over 60 years of age predominate among the patients. The prognosis for lung metastases is usually unfavorable. Due to multiple metastasis, late detection of foci in the lung tissue and concomitant damage to other organs, radical treatment is usually impossible. The exception is solitary metastases in the lungs that occurred long after specific therapy or surgical removal of the primary neoplasm. The treatment is carried out by specialists in the field of oncology and pulmonology.
Etiology and pathanatomy
The reason for frequent lung tissue damage in malignant neoplasms of various localization is a well-developed network of blood and lymphatic vessels in the lung tissue. The cells of the primary tumor migrate through the lymphatic or circulatory system, settle in the lung tissue or under the pleura and give rise to metastases.
In addition, implantation (aspiration) metastasis is possible, in which malignant cells spread through the bronchi from a decaying neoplasm of the upper respiratory tract, bronchus, lung or an aggressively growing tumor of a nearby organ. Secondary tumors in the lung tissue can themselves become a source of metastases in other organs.
Metastases in the lungs are more often diagnosed with primary breast cancer, stomach, esophagus, bladder, colorectal cancer, prostate cancer, liver, melanoma and kidney tumors, but can also be detected with other oncological diseases. Usually they are nodes with a diameter of several millimeters to 5 centimeters or more. They are more often plural. Lung metastases in melanoma can be brown, brownish-black, white or partially pigmented. Nodes in sarcoma and cancer are white or pinkish-gray. Less often, metastases in the lungs are a diffuse network spreading under the pleura and in the thickness of the lung tissue – such secondary neoplasms are found in cancerous lymphangitis caused by the migration of malignant cells through the lymphatic vessels.
Classification
Metastatic foci in the lungs are classified according to several characteristics:
- According to the type of neoplasms: focal and infiltrative forms.
- According to the number of secondary tumors: solitary (single), single (no more than 3), multiple (more than 3).
- In diameter: large and small.
- By localization: one-sided and two-sided.
Taking into account the peculiarities of the spread, two forms of metastases in the lungs are distinguished: disseminated and mediastinal. In the disseminated form, multiple secondary tumors are detected in the lung tissue (as a rule, mainly in the lower parts). In the mediastinal form, the mediastinal lymph nodes are first affected, and then tumor cells migrate through the lymphatic vessels into the lung tissue. Taking into account the peculiarities of the X – ray picture , four forms of lung metastases are distinguished:
- Nodal. It includes the solitary and plural forms. Radiographs reveal nodes with clear contours, localized mainly in the lower parts. The lung tissue outside the foci retains its normal structure.
- Pseudopneumatic (diffuse-lymphatic). The images show multiple thin strands of compacted tissue located in the peribronchial zone. Closer to the hearth, the strands have vague contours, as the boundaries of the seals become clearer as they are removed.
- Pleural. It resembles a picture of exudative pleurisy. An effusion may be detected in the pleural cavity. Lumpy layers are found on the surface of the lungs.
- Mixed. There is a combination of two or more of the above forms.
When determining the tactics of treatment of metastases in the lungs, the degree of sensitivity of the tumor to various types of therapy is important. Taking into account this indicator , the following types of lung metastases can be conditionally distinguished:
- Responding to radiotherapy and chemotherapy (for osteogenic sarcoma, ovarian cancer and testicular cancer).
- Resistant to chemotherapy (for cervical cancer and melanoma).
- Reacting to hormone therapy (with hormone-active neoplasms of the genitals).
Symptoms
At the initial stage, lung metastases are usually asymptomatic. Common signs of cancer can be detected: unmotivated weakness, apathy, anemia, loss of appetite, weight loss, body temperature increase. The first manifestation of lung metastases is usually recurrent colds: flu, bronchitis, pneumonia. Sometimes symptoms occur only in the final stage, with multiple nodes in the lungs, involvement of the bronchi and pleura.
With the defeat of a significant part of the lung or compression of the bronchus, shortness of breath develops. Cough with metastases in the lungs is dry at first, more often occurs at night. Subsequently, mucopurulent sputum appears odorless, often with an admixture of blood. With the narrowing of the bronchi, the sputum becomes thicker, purulent. Pulmonary bleeding is possible. Lung metastases, spreading to the pleura, ribs and spine, provoke the development of pain syndrome. With metastases in the lymph nodes of the left part of the mediastinum, hoarseness of the voice and aphonia may be observed, with lesions of the lymph nodes of the right part of the mediastinum, swelling of the upper half of the body due to compression of the superior vena cava.
Diagnostics
The diagnosis is made taking into account anamnesis, clinical manifestations, results of instrumental and laboratory studies. Patients with suspected lung metastases are referred for chest x-ray, which allows assessing the condition of lung tissue, determining the type, nature and number of secondary neoplasms, the presence of effusion in the pleural cavity. Patients are also prescribed CT of the lungs – this modern technique makes it possible to detect small metastases with a diameter of less than 0.5 mm, including those located subpleurally.
If necessary, to reduce the radiation load (with lung metastases in children, with numerous studies to identify the primary focus and metastatic lesions of other organs, with prolonged observation) and suspicion of the presence of small metastases, MRI of the lungs is performed – this technique allows detecting secondary foci with a diameter of less than 0.3 mm. Lung metastases are confirmed based on the results of cytological examination of sputum and pleural effusion or histological examination of a biopsy obtained during bronchoscopy, percutaneous puncture biopsy of the lung or (less often) open biopsy.
To identify metastases of other localizations, an extended examination is carried out, including ultrasound of the abdominal cavity, scintigraphy of skeletal bones, CT and MRI of the spine, CT and MRI of the brain, ultrasound of the pelvic organs, ultrasound of the retroperitoneal space and other studies. Lung metastases differentiate with peripheral lung cancer, benign lung neoplasm, pneumonia, lung cyst and tuberculosis.
Treatment
Therapeutic tactics are determined by the type of primary tumor, its response to therapy, the number and diameter of metastases in the lungs, the presence or absence of metastatic lesions of other organs, the general condition of the patient and some other factors. The main treatment method is usually chemotherapy, which can be used in isolation or in combination with other methods. With metastases in the lungs that have arisen during the dissemination of hormone-dependent tumors, hormone therapy is prescribed. The best effect of hormonal treatment is observed in prostate cancer and breast cancer.
Radiotherapy is prescribed for secondary foci of reticulosarcoma, Ewing’s sarcoma, osteogenic sarcoma and some other tumors sensitive to radiation exposure. Indications for surgical treatment for lung metastases are limited. Surgical intervention is advisable for single metastases, isolated lesion of the peripheral part of the lung, controlled primary neoplasm and the absence of metastases to other organs. Sometimes two-stage lung resection and liver resection are performed with single metastases in lung and metastatic liver cancer. In some cases, radiosurgery is used or laser resection of the secondary focus is performed. When the large bronchi are compressed, endobronchial brachytherapy is performed.
Forecast
Prognostically unfavorable factors are the appearance of metastases in the lungs earlier than a year after radical treatment of the primary neoplasm, the diameter of the nodes is more than 5 cm, the rapid growth of secondary foci and an increase in intra-thoracic lymph nodes. Long-term survival in some cases is possible after surgical interventions for single metastases in the lungs that occurred a year or more after radical treatment of the primary tumor.
The factors that do not significantly affect the life expectancy of lung metastases include the localization of a secondary focus (central or peripheral), the side of the lesion, the presence or absence of metastatic pleural lesion. The five-year survival rate of patients with single lung metastases after combination therapy is about 40%. The best results are observed in primary neoplasms of the uterus, bones, kidneys, breast and soft tissues.