Clinical updates of approaches for biopsy of pulmonary lesions based on systematic review

Background Convenient approaches for accurate biopsy are extremely important to the diagnosis of lung cancer. We aimed to systematically review the clinical updates and development trends of approaches for biopsy, i.e., CT-guided PTNB (Percutaneous Transthoracic Needle Biopsy), ENB (Electromagnetic Navigation Bronchoscopy), EBUS-TBNA (Endobroncheal Ultrasonography-Transbronchial Needle Aspiration), mediastinoscopy and CTC (Circulating Tumor Cell). Methods Medline and manual searches were performed. We identified the relevant studies, assessed study eligibility, evaluated methodological quality, and summarized diagnostic yields and complications regarding CT-guided PTNB (22 citations), ENB(31 citations), EBUS-TBNA(66 citations), Mediastinoscopy(15 citations) and CTC (19 citations), respectively. Results The overall sensitivity and specificity of CT-guided PTNB were reported to be 92.52% ± 3.14% and 97.98% ± 3.28%, respectively. The top two complications of CT-guided PTNB was pneumothorax (946/4170:22.69%) and hemorrhage (138/1949:7.08%). The detection rate of lung cancer by ENB increased gradually to 79.79% ± 15.34% with pneumothorax as the top one complication (86/1648:5.2%). Detection rate of EBUS-TBNA was 86.06% ± 9.70% with the top three complications, i.e., hemorrhage (53/8662:0.61%), pneumothorax (46/12432:0.37%) and infection (34/11250:0.30%). The detection rate of mediastinoscopy gradually increased to 92.77% ± 3.99% with .hoarseness as the refractory complication (4/2137:0.19%). Sensitivity and specificity of CTCs detection by using PCR (Polymerase Chain Reaction) were reported to be 78.81% ± 14.72% and 90.88% ± 0.53%, respectively. Conclusion The biopsy approaches should be chosen considering a variety of location and situation of lesions. CT-guided PTNB is effective to reach lung parenchyma, however, diagnostic accuracy and incidence of complications may be impacted by lesion size or needle path length. ENB has an advantage for biopsy of smaller and deeper lesions in lung parenchyma. ENB plus EBUS imaging can further improve the detection rate of lesion in lung parenchyma. EBUS-TBNA is relatively safer and mediastinoscopy provides more tissue acquisition and better diagnostic yield of 4R and 7th lymph node. CTC detection can be considered for adjuvant diagnosis.


Background
Lung cancer is the most frequently diagnosed cancer and continues to be the leading cause of cancer mortality among both males and females [1]. The 5-year survival rate of lung cancer is only 18%, largely due to late-stage diagnosis [1]. Thus, early diagnosis is especially critical to improve long-term survival. Biopsy is important for identification and confirmation of lung cancer. In clinical practice, conventional flexible bronchoscopy is supposed to be difficult for biopsy of small lesions in lung parenchyma or mediastinum. Therefore, we focused on the following approaches for biopsy according to a variety of lesion location in lung parenchyma, i.e., CT-guided PTNB(Percutaneous Transthoracic Needle Biopsy), ENB (Electromagnetic Navigation Bronchoscopy), EBUS-TBNA (Endobroncheal Ultrasonography-Transbronchial Needle Aspitation) and mediastinoscopy. Furthermore, the studies regarding liquid biopsies, e.g., CTC (Circulating Tumor Cell) detection are timely and hot, and warrant to be systematically reviewed.
Therefore, we evaluated the published studies in the last 20 years which focused on CT-guided PTNB, ENB, EBUS-TBNA, mediastinoscopy and CTC, aiming to reveal the clinical updates, development trends, detection rates and complications.

Methods
We used systematic review to identify relevant studies, assess study eligibility, evaluate methodological quality, and summarize findings regarding postoperative clinical outcomes. Medline and manual searches were performed by investigators CJD and FQD independently and jointly to identify all published articles in English journals from January 1, 2000 to November 9, 2017 that addressed the issues regarding detection of lung cancers by using CT-guided PTNB, ENB, EBUS-TBNA, mediastinoscopy and CTCs, respectively. The Medline search was done on PubMed (http://www.ncbi.nlm.nih.gov). The search strategies and yielded citations were shown in Tables 1 and 2, respectively. Investigators CJD and FQD performed the actual search and data abstraction.

Data abstraction
From the eligible articles, investigators CJD and FQD reviewed the following information, i.e., PMID, year of publication, study design, number of patients, average age of patients, nodules size and location, operation time, biomarkers for detection, diagnostic sensitivity, relative complication morbidity, treatment of complications, outcome and follow-up period.

Statistical analysis
The association between detection rate of ENB and nodule size, number of cases, operation time, average age of patients, sex, and mean distance of the lesions from the pleura was performed using Pearson's correlation analysis. The impact of nodule location on detection rate of ENB was analyzed by using ANOVA analysis. The association between morbidity of pneumothorax following ENB and nodule size was performed using Pearson's correlation analysis. The analyses were performed using SPSS Version 11.0 software for Windows (SPSS, Inc., Chicago, IL, USA). P < 0.05 (two-sided) was considered to indicate a statistically significant difference.

CTC: Biopsies of tumor cells shed from solid tumor lesion into peripheral blood
The mean sensitivities of a variety of methods to detect CTC remained to be 63.05%. As shown in Fig. 3a, sensitivity of PCR seemed to be highest (78.81 ± 14.72%). Sensitivity of Density-gradient, ISET and Magnetic bead seemed to be higher than 60% (71.32% ± 2.8%, 67.75% ± 21.22% and 67.85% ± 25.24%, respectively). Specificity of ISET, PCR and Cell search was relatively high (100%, 90.88 ± 0.53% and 94.33% ± 9.82%, respectively). There was no published data regarding specificity of Magnetic bead and density-gradient. Intriguingly, there are a variety of biomarker combination for CTCs identification by using PCR yielding different sensitivities. As shown in Fig. 3b, the sensitivity of Multimarker assay seemed to be highest (90%). Besides, the sensitivity of the combination of TSA-9, KRT-19, Pre-proGRP was satisfactory (84.3%).
CT-guided PTNB is regarded as an effective and feasible procedure to detect a difficult nodule with advantage of accurate positioning and high detection accuracy. Nevertheless, once the lesion diameter is less than 2 cm or the needle path length is more than 8 cm, the detection rate will drop dramatically [4]. In addition, the lesions in the vicinity of mediastinum vessels are challengers to clinicians with regards to safety. Currently, ENB is developed for biopsy of the lesions in deep lung parenchyma or mediastinum.
ENB is recommended in patients with lesions in lung parenchyma difficult to reach with conventional bronchoscopy or CT-guided PTNB. The detection rate of ENB increased gradually probably due to improvement of software and hardware. Eberhardt et al. [20] found nodule location has been noted to be an important factor in diagnostic yield, e.g., the yields from the lower lobes were significantly lower (29%; p = 0.01). However, Jensen et al. [22] found lobar location of nodule did not affect the diagnostic yield (p = 0.59). Therefore, we systematically analyzed the results of six studies mentioning detection rate and nodule location [14,20,22,27,29,66], and found that there seemed to be no association between them (p = 0.433). The highest incidence of complication is pneumothorax (5.2%). However, pneumothorax following ENB was reported to be unrelated with age or sex [16], accordant with our results. Intriguingly, the incidence of pneumothorax seemed to be significantly negatively correlated with nodule size, probably due to difficulties varying with the size. Additionally, The detection rate by using mediastinoscopy increased slightly. c The positive rate of 4 th R (91.5% ± 9.35%) and 7th (80.56% ± 19.47%) lymph node by using mediastinoscopy were significantly higher than others (P < 0.05). d Hoarseness (67/4387:1.53%) was the top one complication following mediastinoscopy there was no reported ENB associated death, proving that ENB is relatively safe.
Empirically, EBUS-TBNA is suitable for biopsy of lesion in subcarinal and bilateral hilar area. EBUS-TBNA is also well utilized in the peripheral area with radial probe EBUS and in conjunction with ENB. As EBUS-TBNA has relatively high false negative rates, especially at station 4R or 7 lymph node, mediastinoscopy is still required for patients with suspicious nodal disease in these stations [67]. Cytological samples are usually taken by EBUS-TBNA, however, larger histological tissue samples are possible to obtain by mediastinoscopy.
Mediastinoscopy is always recognized as the gold standard for surgical staging of lung cancer which is suitable for biopsy in the vicinity of the trachea, the subcarinal and the bronchi area. Especially, the positive rate of station 4R th (91.5 ± 9.35%) and 7th (80.56 ± 19.47%) lymph node were significantly higher than other stations (Fig. 2c). Nevertheless, as mediastinoscopy is an invasive approach, the incidences of complications are relatively remarkable.
CTC is a kind of liquid biopsies of tumor cells shed from solid tumor lesions (primary foci and metastases) into peripheral blood. Although the mean sensitivities of CTC detection were not satisfactory, the convenience of this non-invasive method seems to be incomparable. Sensitivity of PCR remained to be highest (78.81% ± 14.72%) as compared with other methods. Intriguingly, the sensitivities of PCR varies with combined biomarkers. Expectedly, the sensitivity of combination of multimarkers assay is highest (90%). Furthermore, the specificity of the three methods, i.e., ISET, PCR and Cell search, was relatively high (100%, 90.88% ± 0.53% and 94.33% ± 9.82%, respectively). Currently, CTC can be used as an auxiliary diagnostic method to provide a higher detection rate.

Conclusions
The biopsy approaches should be chosen according to a variety of location and situation of lesions. CT-guided PTNB is regarded as an effective and feasible procedure for biopsy in lung parenchyma, however, diagnostic accuracy and incidence of complications may be impacted by lesion size or needle path length. ENB has an advantage for biopsy of smaller and deeper lesions in lung parenchyma. ENB plus EBUS imaging can further improve the detection rate. EBUS-TBNA and mediastinoscopy can be recommended for the biopsy in lower and upper mediastinum, respectively. The former is relatively safer and the latter provides more tissue acquisition and better diagnostic yield of 4R and 7th lymph node. CTC detection can be considered for adjuvant diagnosis.