The diagnosis of lung cancer includes two major steps: localization and qualitative diagnosis of intrapulmonary lesions and tumor staging. The clinical diagnosis of lung cancer must be based on a comprehensive analysis of clinical manifestations and various imaging findings, but the final diagnosis must be confirmed by obtaining cytological or pathological histological evidence. Any diagnosis without cytologic or pathologic histologic evidence cannot be considered as the final diagnosis. In the comprehensive selection of using various diagnostic tools, it should be based on the principle of simple to complex and non-invasive to invasive first.
Section I. Basic diagnostic steps of lung cancer
(I) Basic diagnostic measures of lung cancer
The basic diagnostic measures of lung cancer include medical history and physical examination, frontal and lateral chest radiographs, complete blood cell examination and biochemical examination.
1.Men aged >45 years with smoking index >400 times are at high risk of lung cancer, and lung physical examination at least once a year is recommended.
2.Patients with cough with blood sputum should be highly suspected of lung cancer.
Cough (70%), bloody sputum (58%), chest pain (39%), fever (32%) and shortness of breath (13%) are the five common symptoms, of which the most common symptom is cough and the most diagnostic symptom is bloody sputum.
The most common symptom is cough, and the most diagnostic symptom is bloody sputum. 3.Symptomatology of lung cancer is not specific.
4. If abnormal chest X-ray is found in annual physical examination, such as fibroproliferative lesions after recovering from tuberculosis, annual follow-up examination should be conducted, and the possibility of lung scar cancer should be further excluded if the lesions increase.
5.The appearance of hoarseness and head and face swelling in lung cancer indicates the possibility of advanced local stage.
5-10% of lung cancer patients have upper vena cava obstruction syndrome as the first symptom. Other symptoms of local invasion of lung cancer include Horner syndrome, Pancoast syndrome, and hoarseness involving the laryngeal recurrent nerve.
6.Patients with lung cancer who have recently developed headache, nausea or other neurological signs and symptoms should consider the possibility of brain metastasis. Bone pain, elevated blood alkaline phosphatase or blood calcium should be considered as possible bone metastases. Right upper abdominal pain, hepatomegaly, elevated alkaline phosphatase, glutamic transaminase, lactate dehydrogenase or bilirubin should be considered as possible liver metastasis. In case of subcutaneous metastasis, nodules can be palpated under the skin; bloodstream metastasis to other organs can be seen as symptoms of the metastatic organ.
7. In cases of confirmed lung cancer, behavioral status scores such as Karnofsky or ECOG should be performed. The behavioral status of lung cancer patients is one of the most important prognostic factors.
Lagakos’ ECOG study showed that patients who lost more than 5% of their body weight within six months before treatment had a significantly worse prognosis than those who had more than 5%.
(ii) Frontal and lateral chest radiographs
Patients with clinical suspicion of lung cancer should routinely undergo chest ortholateral radiography. Lateral chest radiography is an important basic method to detect and diagnose lung cancer and provide reference for treatment. About 5%-15% of lung cancer patients can be found without any symptoms by X-ray examination alone.
(iii) Sputum cytology examination
Sputum cytology examination is routinely performed for clinically suspected lung cancer cases.
Sputum cytology is one of the simple and convenient non-invasive diagnostic methods for lung cancer diagnosis. Its biggest advantage is that positive cytology results can be obtained before the lesion is detected by imaging. Lung cancer with positive sputum cytology and no lesion detected by imaging or bronchoscopy is called occult lung cancer.
(iv) Fiberoptic bronchoscopy
Fiberoptic bronchoscopy should be routinely performed in lung cancer cases with clinical suspicion of stage I-IIIA, which is the most important tool in lung cancer diagnosis. Fiberoptic bronchoscopy allows direct observation of lesions in the trachea and bronchi, and can be performed under direct visualization by clamping and wiping to obtain pathological histology or cytology for diagnosis. Techniques using bronchial mediastinum or pulmonary puncture have also been developed for lesions located more peripherally. Some research units have also used hematoporphyrin laser lung cancer localization techniques to diagnose carcinoma in situ or invisible lung cancer that is not observed with the naked eye.
(v) Needle aspiration cytology
For lung lesions that cannot be diagnosed by conventional sputum cytology or non-invasive examinations such as fiberoptic bronchoscopy, transthoracic needle aspiration cytology or histology (TTNA) can be performed under the guidance of CT or ultrasound, and the puncture tool used can be a fine needle or a special puncture biopsy gun. However, fine needle aspiration is often used to obtain cytological specimens. This test is invasive and has the potential to cause pneumothorax, hemorrhage, and, rarely, needle tract implantation metastasis. For early lesions, TTNA should be limited to those who are unwilling to undergo surgery or have contraindications to surgery.
(F) Intraoperative rapid frozen section examination
Isolated nodular lesions in the lung without contraindications to surgery should be selected for thoracoscopic wedge resection or dissecting thoracotomy + intraoperative rapid frozen section examination, with simultaneous diagnosis and treatment. More than 60% of SPNs are malignant when the diameter is 45 years old, and more than 80% of SPNs are malignant when the diameter of the nodule is >1 cm.
(VII) Nodes suspected of metastasis
If the lymph nodes or subcutaneous nodes suspected of metastasis cannot be excised for biopsy, fine needle aspiration cytology should be performed first instead of partial excision histological examination.
Section 2: Staging diagnosis of lung cancer
(a) For cases of lung cancer suspected by frontal and lateral chest radiographs, CT examination of the chest is routinely performed
Chest CT examination has become a routine method to estimate the degree and extent of invasion within lung cancer, especially in the staging of lung cancer, which has its irreplaceable role. Compared with X-ray, CT chest examination has the advantages of detecting lung lesions smaller than 1 cm and those located in overlapping anatomical areas that are difficult to be detected by conventional chest X-ray, and it is easy to determine the relationship between lung cancer and surrounding tissues and organs.
Since the lung and adrenal glands are located close to each other and the adrenal glands are common metastatic sites of lung cancer, it is recommended to routinely downscan several layers including the adrenal glands during chest CT examination of lung cancer, so as to reduce the waste of medical resources.
The main purpose of CT examination of other parts including brain, liver and adrenal gland is to remove distant metastasis of lung cancer, which is usually performed only when there is clinical suspicion of metastasis or before surgery.
(b) For clinical diagnosis of supraglottic sulcus tumor, MRI of the spine + thoracic inlet is recommended to understand the anatomical relationship between the subclavian and vertebral arteries and the tumor.
(iii) For mediastinal lymph nodes with the smallest diameter >1 cm on imaging, transjugular mediastinoscopy is recommended
The size of mediastinal lymph nodes is still the main method of CT diagnosis to determine whether the lymph nodes are metastatic or not. A large number of studies have found that the false positive rate of CT in determining whether the mediastinal lymph nodes are metastatic is 40%. For patients with cNo-1, transjugular mediastinoscopy is recommended to determine the treatment strategy due to the significant change in treatment strategy.
In the map of mediastinal lymph node distribution in lung cancer (Figure 1), paratracheal lymph nodes (groups 2 and 4 lymph nodes), anterior tracheal lymph nodes (groups 1 and 3 lymph nodes) and ramus lymph nodes (groups 7 lymph nodes) can be determined by cervical mediastinoscopy. The aortic window lymph nodes and ascending aortic lymph nodes (groups 5 and 6 lymph nodes) can be determined by parasternal mediastinoscopy, while the lower mediastinal lymph nodes (groups 8 and 9 lymph nodes) are blind to mediastinoscopy.
(d) Imaging staging items for locally advanced non-small cell lung cancer (NSCLC J) should routinely include chest CT, cranial MBI, upper abdominal CT or ultrasound, and bone nuclear scan.
The four most common sites of metastasis in NSCLC are brain, bone, liver and adrenal gland, and the incidence of metastasis at these sites increases with the increasing stage of lung cancer. Therefore, CT or ultrasound of the upper abdomen and bone nuclide scan are performed for locally advanced NSCLC.
(v) In clinical stage IIIB lung cancer, cytoscopy can be considered when other tests fail to obtain a pathological diagnosis.
Video-assisted thoracoscopic surgery (VATS) is one of the rapidly developing minimally invasive surgical techniques in recent years, which plays an increasingly important role in the diagnosis, differential diagnosis, staging and treatment of lung cancer. Its diagnostic indications are mainly: pleural lesions; malignant pleural fluid; diffuse lesions of the lung or excisional biopsy of small isolated nodules in the periphery of the lung, etc. It should be noted that thoracoscopy is an invasive test, therefore, it is usually considered for diagnostic purposes only in cases where the diagnosis is still not confirmed after the execution of other non-invasive tests.
(vi) Clinical stage of locally advanced NSCLC, and clinical studies of PET or PET/CT whole-body examination are recommended in hospitals where available.
Positron cmission tomography PET is a new technique developed in the 1990s, and its mechanism is to use the difference in the surrogate emission of fluoro-2-deoxy-D-glucose between normal cells and lung cancer cells to have different images. It is basically both localizing and qualitative examination, mainly used to exclude intrathoracic lymph nodes and distant metastases, and also very suitable for differential diagnosis of uncontrolled tumor and scar tissue after radiotherapy.
The current study illustrates that PET has 84% sensitivity, 93% specificity, 7% false negatives and 16% false positives in diagnosing whether there are metastases in intrathoracic mediastinal lymph nodes; 93% sensitivity, 88% specificity, 8% false negatives and 10% false positives in diagnosing distant metastases. change the development of treatment strategy, but the test is expensive and less popular, so it is recommended to carry out clinical studies of PET whole-body examination in hospitals that have the conditions.
(vii) In cases with pleural fluid, thoracentesis is feasible, fresh pleural fluid is withdrawn, processed by centrifugation, and the sediment is taken for smear to find cancer cells.
(H) For clinical IV lung cancer, CT-enhanced scan or magnetic resonance imaging (MR) examination of the brain should be performed only when brain metastasis is suspected.
(ix) For clinical IV lung cancer, ECT examination of bone should be performed only when bone metastasis is suspected.
(j) In hospitals with conditions, blood CEA level can be measured as a tumor marker to estimate disease stage, prognosis and response to treatment.
To date, a marker with good specificity for lung cancer retention has not been identified. Abnormally high levels of carcinoembryonic antigen (CEA) are found in 30%-70% of lung cancer patients, but mainly in patients with advanced lung cancer, especially in patients with lung adenocarcinoma; abnormally high levels are also found in 20%-60% of patients with small cell lung cancer. Currently, CEAE in serum is mainly used to estimate disease prognosis and response to treatment.
(xi) Before starting treatment, the diagnosis of lung cancer should be clearly small cell lung cancer, and the stage should also be clearly defined.
In 2004, the World Health Organization published the new WHO histologic classification of lung cancer (see Chapter 2), in which the incidence of the four most prominent types of lung cancer are, in order, 31.5% for adenocarcinoma, 29.4% for squamous carcinoma, 17.8% for small cell carcinoma, and 9.2% for large cell carcinoma. Among them, adenocarcinoma is on the rise and squamous carcinoma is on the decline.
In 1997, the International Union Against Cancer published the revised international staging of lung cancer (see Chapter 2), and small cell lung cancer continues to be divided into limited stage and extensive stage. Small cell lung cancer in the limited stage should be further clinically staged according to TNM stage, so that the best treatment can be more accurately individualized for different stages.