At present, surgery is still the preferred treatment for early-stage lung cancer, and the 5-year survival rate after surgery can reach over 70%, while the 5-year survival rate for localized mid- to late-stage lung cancer surgical treatment is only about 20%. Early detection, early diagnosis and early treatment are the most effective measures to improve the cure rate and reduce the mortality rate of lung cancer. In recent years, advances in medical imaging technology, endoscopic technology and minimally invasive surgical techniques have led to profound changes in the diagnosis and treatment strategies for early stage lung cancer.
Early diagnosis of lung cancer
Several clinical studies conducted in the 1970s using sputum cytology and chest X-rays to screen for early lung cancer found that although more lung cancers were detected and more surgical treatments were performed, the overall mortality rate from lung cancer was not significantly reduced. In recent years, with the development of imaging technology, especially spiral CT scanning, more small volume peripheral type lung nodules can be detected. Countries such as the United States, Japan, and Europe have begun screening studies for early lung cancer using low-dose spiral CT scans (LDCT).
The results of I-ELCAP were reported in the New England Journal of Medicine in 2006. LDCT was found to have a significantly higher positive rate of detecting small lung nodules than conventional chest X-rays, with more than 80% of screened lung cancer patients having stage I lung cancer and a 10-year survival rate of more than 90% after surgical resection. The authors concluded that participation in screening reduced the risk of death from lung cancer, and hypothesized that low-dose spiral CT screening could reduce lung cancer deaths by 80%.
Pre-surgical staging
1.T-staging of primary tumor
Chest CT can more accurately evaluate the size of the primary lung tumor and its invasion of the chest wall, diaphragm and important organs of mediastinum, and fiberoptic bronchoscopy can visually observe the specific location of the tumor and the distance from the ramus and main bronchus. For some cases where the primary tumor is close to the periphery of the lung and conventional fiberoptic bronchoscopy cannot obtain positive results and its location is not suitable for percutaneous lung puncture biopsy, the advent of electromagnetic navigation bronchoscopy (ENB) has made this difficult problem easy.
2.N-staging of regional lymph nodes
For lung cancer without distant metastasis, the clear presence or absence of mediastinal lymph node metastasis is a key factor in deciding the treatment modality.
The sensitivity and specificity of chest-enhanced CT for determining mediastinal lymph node metastasis were 51% (95% CI, 47-54%) and 86% (95% CI, 84-88%), respectively. Although its accuracy is not high, it is the best clinical study method for noninvasive mediastinal dissection, allowing further invasive examination of suspected mediastinal lymph nodes and improving accurate anatomical localization and pathological diagnosis.
The sensitivity and specificity of PET-CT in evaluating N-stage of lung cancer were found to be 74% (95% CI, 69-79%) and 85% (95% CI, 82-88%), respectively, in 44 clinical studies with complete data from 1994 to 2006.
② Invasive staging methods for lymph nodes of lung cancer. To this day, mediastinoscopy remains the gold standard for N-staging of mediastinal lymph nodes in lung cancer. With the maturation and popularization of new technologies such as transbronchoscopic aspiration biopsy (TBNA), transesophageal ultrasound-guided aspiration biopsy (EUS-NA), and transtracheoscopic ultrasound-guided aspiration biopsy (EBUS-TBNA), the means of mediastinal lymph node staging for lung cancer has begun to diversify.
The mediastinal lymph nodes that can be biopsied by EBUS-TBNA include groups l, 2, 4, and 7, but the para-aortic and inferior mediastinal lymph nodes (groups 5, 6, 8, and 9) are more difficult to be explored. Since the outside diameter of the ultrasound endoscopic probe is only 6.9 mm, it can penetrate deep into the main bronchus and even the lobar bronchus to explore groups l0, 11, and some of the group 12 lymph nodes.
With the increased clinical use of EBUS-TBNA, the use of mediastinoscopy in lung cancer staging has gradually decreased, and clinical practice guidelines for lung cancer such as the National Comprehensive Cancer Network (NCCN) and the American College of Chest Physicians (ACCP) have recommended EBUS as one of the standard methods for mediastinal lymph node staging of lung cancer since 2007. the combined use of EUS-NA and EBUS-NA allows for un The sensitivity and false-negative rate of the combination were 97% and 2%, respectively, in a group of NSCLC with a 42% mediastinal lymph node metastasis rate.
Surgical modalities for early stage lung cancer
1.Minimally invasive thoracic surgery
Kirby TJ was the first to report VATS lobectomy in the early 1990s, after which this technique gradually became popular worldwide. Some early thoracic surgeons could not accept thoracoscopic lobectomy for lung cancer;
The main concerns were twofold.
In 2006, McKenna RJ reported the clinical results of 1,100 VATS Lobectomy cases, 84.7% of patients had no postoperative complications, 2.5% had an open-chest conversion, 4.1% required blood transfusion, the median length of stay was 3 days, and the incisional recurrence rate was 0.57%. This result showed a better surgical safety.
It is now believed that peripheral non-small cell lung cancer in clinical stage I is the best indication for VATS, and the safety and efficacy of the procedure are no longer significantly different compared with conventional open-heart surgery. Postoperative complications are significantly lower than those of traditional open-heart surgery. The results of a multi-center clinical study led by the Lung Cancer Center of Capital Medical University on adjuvant chemotherapy after lung cancer surgery in China and the United States showed that the number of days of hospitalization after VATS was shorter than that of traditional open-heart surgery, and the time of starting adjuvant chemotherapy was significantly earlier than that of open-heart surgery.
2.Sublobectomy
With the advent of multi-row spiral CT technology, lung cancer has the opportunity to be clinically detected at an earlier stage, and the clinical application of PET makes the diagnosis and staging of lung cancer more accurate than before. Some scholars have selected some early peripheral type NSCLC with diameter less than 2 cm to perform lung segmental resection or wedge resection plus regional lymph node removal and obtained the same clinical results as lobectomy. Japanese scholars reported sublobar resection plus regional lymph node sampling for peripheral type lung cancer less than 2 cm in diameter with a 5-year survival rate of 93%.
Compared to lung wedge resection, lung segmental resection obtained better local control and had more accurate pathological staging. There are still many uncertainties regarding lung segmental resection for lung cancer, mainly in the following areas.
Tumor size and location Several studies have shown no significant difference in 5-year DFS between segmental lung resection and lobectomy in tumors ≤2 cm, 84.6% and 87.4%, respectively. In addition, to ensure adequate margins, those tumors located in the peripheral 1/3 of the lung and in the anatomical center of the lung segment to be resected should be selected, with margins of 15 mm or more on both sides. Otherwise, it is advisable to choose a lung segment consistent with resection or lobectomy.
Special pathological types.
Gross glassy nodules (GGO) are a special group. CT-detected GGO are more likely to be carcinoma in situ or early-stage NSCLC, so this group of patients may benefit more from lung segmental resection. It has been found that patients with non-mucinous BAC can achieve 100% DFS with lung segmental resection. Pulmonary segments suitable for anatomic segmental resection Pulmonary segmental resection procedures commonly used in clinical practice currently include left intrinsic upper lobe resection, lingual segmental resection, bilateral lower lobe dorsal segmental resection and basal segmental resection, others such as simple anterior or posterior upper lobe segmental resection are less commonly used. The local recurrence rate of segmental lung resection for lung cancer located in S1-3 segments of the upper lobe is as high as 23%, and segmental lung resection is not recommended.
It is important to emphasize that samples of hilar and segmental lymph nodes should be taken and rapid frozen pathology should be performed before performing segmental lung resection. If the frozen pathology is positive, the procedure should be changed to lobectomy, and if the frozen pathology is negative, lung segment resection should be continued. Currently, the main evidence for lung segment resection for early-stage lung cancer comes from retrospective studies, and there is a lack of results from prospective multicenter randomized controlled clinical studies with large samples. Therefore, it is controversial whether segmental lung resection can become the standard procedure for early-stage lung cancer. Four large-sample multicenter prospective randomized clinical trial programs (American College of Surgeons Collaborative Oncology Group [ACOSOG] Z4032; Cancer and Leukemia Group B [CALGB] 140503 and Japanese Clinical Oncology Group [JCOG] 0804) are currently evaluating the efficacy of sublobar resection for early-stage lung cancer.
Summary
In conclusion, with the development of screening tools and examination techniques, “early detection, early diagnosis, and early treatment” of lung cancer is possible. The future of early lung cancer diagnosis and treatment The future of early stage lung cancer diagnosis and treatment is a multidisciplinary treatment model combining surgery, medical oncology, radiotherapy, imaging and pathology, and an individualized treatment model combining clinical and molecular biology techniques. With the clinical application of these new treatment strategies, a solid foundation is laid for us to improve the efficacy of early lung cancer treatment and improve survival.