Sentinel nodal assessment in patients with carcinoma of the lung

Sentinel Lymph Node in Non-Small Cell Lung Cancer: Assessment of Feasibility and Safety by Near-Infrared Fluorescence Imaging and Clinical Consequences

Occult micrometastases can be missed by routine pathological analysis. Mapping of the pulmonary lymphatic system by near-infrared (NIR) fluorescence imaging can identify the first lymph node relay. This sentinel lymph node (SLN) can be analyzed by immunohistochemistry (IHC), which may increase micrometastasis detection and improve staging. This study analyzed the feasibility and safety of identifying SLNs in thoracic surgery by NIR fluorescence imaging in non-small cell lung cancer (NSCLC). This was a prospective, observational, single-center study. Eighty adult patients with suspected localized stage NSCLC (IA1 to IIA) were included between December 2020 and May 2022. All patients received an intraoperative injection of indocyanine green (ICG) directly in the peri tumoural area or by electromagnetic navigational bronchoscopy (ENB). The SLN was then assessed using an infrared fluorescence camera. SLN was identified in 60 patients (75%). Among them, 36 SLNs associated with a primary lung tumor were analyzed by IHC. Four of them were invaded by micrometastases (11.1%). In the case of pN0 SLN, the rest of the lymphadenectomy was cancer free. The identification of SLNs in thoracic surgery by NIR fluorescence imaging seems to be a feasible technique for improving pathological staging.

Diversity of lymphatic flow in patients with lung cancer revealed by computed tomography lymphography

OBJECTIVES

This study was conducted to verify the optimal extent of lymph node dissection or sampling during lung cancer surgery based on the sentinel node (SN) map created by computed tomography (CT) lymphography.

METHODS

From April 2010 to January 2015, patients with clinical stage I non-small-cell lung cancer, who were candidates for lobectomy or segmentectomy with standard hilar and mediastinal lymph node dissection, and in whom bronchus reached the tumour, were enrolled. An ultrathin bronchoscope was inserted to the target bronchus under the guidance of virtual bronchoscopic navigation images. CT images of the chest were obtained 30 s after 2.5 ml of iopamidol was injected. SNs were identified when the maximum CT attenuation value of the lymph nodes on postcontrast CT images increased by 30 Hounsfield units or more compared with the precontrast images. Patients underwent lobectomy with standard lymph node dissection.

RESULTS

SNs were identified in 36 (87.8%) of the 41 patients. The average number of SNs was 1.6 (range, 1-4). There was 1 false negative case; therefore, the accuracy of SN identification was 97.2% (35/36). In 5 (13.9%) of 36 patients, SNs were outside the lobe-specific lymph node station range (#11i from right S1, #7 from right S1, #4R from right S8, #12u from right S8, #7 and #12l from left S1 + 2).

CONCLUSIONS

CT lymphography demonstrated the diversity of lymphatic spreading patterns and there were cases in which lymph flows are found outside the lymph node dissection range.

Long-term outcomes of sentinel node identification using indocyanine green in patients with lung cancer

BACKGROUND

Sentinel node (SN) biopsy is used in the management of numerous cancers to avoid unnecessary lymphadenectomy. This was a clinical exploration/feasibility study of a novel identification technique for SN biopsy using indocyanine green (ICG) fluorescence imaging during lung cancer surgery.

METHODS

SN biopsy using ICG was performed on 22 patients who had cT1 or T2N0M0 lung cancer. ICG was injected just around the primary tumor. The fluorescence imaging system enabled visualization of the lymphatic vessels draining from the primary tumor toward the lymph nodes. Fluorescently labeled nodes were dissected, and patients were followed-up for prognosis and recurrence to confirm the pattern of lymph node metastasis after surgery.

RESULTS

SNs were successfully identified in 16 (72.7%) of 22 patients. A total of 13 of 16 patients had pathological N0 and three had SN metastasis. The median follow-up time was 92.7 months. Only one patient had no SN metastasis at the postoperative pathological examination and lymph node metastasis during the follow-up period. The accuracy rate was 93.8% (15/16) and the false-negative rate was 7.7% (1/13).

CONCLUSIONS

SNs were identified by ICG fluorescence imaging, and this technique during lung cancer surgery had good identification and accuracy rates throughout the follow-up period.

KEY POINTS

SIGNIFICANT FINDINGS OF THE STUDY: We attempted to identify sentinel lymph nodes by indocyanine green in lung cancer surgery. The identification rate was 72.7%. The accuracy rate was 100% immediately after surgery, and 93.8% after follow-up.

WHAT THIS STUDY ADDS

Sentinel node biopsy by indocyanine green may be useful for lymph node dissection during lung cancer surgery to avoid unnecessary lymphadenectomy.

Finding the "True" N0 Cohort: Technical Aspects of Near-infrared Sentinel Lymph Node Mapping in Non-small Cell Lung Cancer

OBJECTIVE

To examine technical-, patient-, tumor-, and treatment-related factors associated with NIR guided SLN identification.

BACKGROUND

Missed nodal disease correlates with recurrence in early stage NSCLC. NIR-guided SLN mapping may improve staging and outcomes through identification of occult nodal disease.

METHODS

Retrospective analysis of 2 phase I clinical trials investigating NIR-guided SLN mapping utilizing ICG in patients with surgically resectable NSCLC.

RESULTS

In total, 66 patients underwent NIR-guided SLN mapping and lymphadenectomy after peritumoral ICG injection. There was significantly increased likelihood of SLN identification with injection dose ≥1 mg compared to <1 mg (65.2% vs 35.0%, P = 0.05), lung ventilation after injection (65.2% vs 35.0%, P = 0.05), and albumin dissolvent (68.1%) compared to fresh frozen plasma (28.6%) and sterile water (20.0%) (P = 0.01). In patients receiving the optimized ICG injection, there was significantly increased likelihood of SLN identification with radiologically solid nodules compared to sub-solid nodules (77.4% vs 33.3%, P = 0.04) and anatomic resection compared to wedge resection (88.2% vs 52.2%, P = 0.04). Disease-free and overall survival are 100% in those with a histologically negative SLN identified (n = 25) compared to 73.6% (P = 0.02) and 63.6% (P = 0.01) in patients with node negative NSCLC established via routine lymphadenectomy alone (n = 22).

CONCLUSIONS

SLN(s) are more reliably identified with ICG dose ≥1 mg, albumin dissolvent, post-injection lung ventilation, radiologically solid nodules, and anatomic resections. To date, N0 status when established via NIR SLN mapping seems to be associated with decreased recurrence and improved survival after surgery for NSCLC.

Sentinel lymph node biopsy for lung cancer

Sentinel lymph node biopsy is a technique to identify the first lymph node (or nodes) draining a tumor. The underlying principle is that as the first site of cancer spread, evaluation of the sentinel node will be most predictive for wider nodal involvement. The introduction of sentinel node biopsy revolutionized the surgical management of cutaneous melanoma and breast cancer, becoming a key component in the management of such patients. For over 20 years, thoracic surgeons have similarly worked to apply this technique to lung cancer but have thus far not had the same impact on lung surgery. In this review, we will summarize the ongoing discussions on the role of sentinel node biopsy in lung cancer, the methods for identifying the sentinel node, and the techniques for evaluating the sentinel node specimen. We will also highlight some of the pressing questions investigators should consider when designing a trial for sentinel node mapping. This will clarify the current status of sentinel node biopsy in lung cancer and thus highlight important future directions for research.

Recent fluorescence imaging technology applications of indocyanine green in general thoracic surgery

Thoracic surgeons perform a wide variety of cancer operations, which are often associated with high morbidity and mortality. Thus, thoracic surgery involves many special challenges that require innovative solutions. The increased utilization of minimally invasive practices, poor overall cancer survival, and significant morbidity of critical operations remain key obstacles to overcome. Fluorescence imaging technology (FIT), involving the implementation of fluorescent dyes and imaging systems, is currently used as an adjunct for general thoracic surgery in many situations and includes sentinel lymph node mapping, pulmonary intersegmental plane identification, pulmonary nodule identification, pulmonary bullous lesion detection, evaluation of the anastomotic perfusion after tracheal surgery, and thoracic duct imaging for postoperative chylothorax. This technology enhances the surgeon's ability to perform operations, and has specific advantages. We review some of the key studies that demonstrate the applications of FIT in the field of general thoracic surgery, focusing on the use of indocyanine green.

Infrared intraoperative fluorescence imaging using indocyanine green in thoracic surgery

Thoracic surgery faces many unique challenges that require innovative solutions. The increase in utilization of minimally invasive practices, poor overall cancer survival and significant morbidity of key operations remain key obstacles to overcome. Intraoperative fluorescence imaging is a process by which fluorescent dyes and imaging systems are used as adjuncts for surgeons in the operating room. Other surgical subspecialists have shown that intraoperative fluorescence imaging can be applied as a practical adjunct to their practices. Thoracic surgeons over the last 15 years have also used intraoperative fluorescence imaging for sentinel lymph node mapping, lung mapping, oesophageal conduit vascular perfusion and lung nodule identification. This review describes some of the key studies that demonstrate the applications of intraoperative near-infrared fluorescence imaging.

Sentinel lymph node mapping in patients with operable non-small cell lung cancer

BACKGROUND

The aim of this study was to determine the accuracy and the role of the sentinel lymph node (SLN) in patients with non-small cell lung cancer.

MATERIAL AND METHOD

This study was carried out on 25 consecutive patients [M/F=23(:)2, mean age 62.84 (47-81) years] with operable non-small cell lung cancer (NSCLC). At thoracotomy, 0.25 mCi of Technecium(99m) (99mTc) nanocolloid was injected into each quadrant of lung tissue surrounding the tumor. Before resection scintigraphic measurements of lymph nodes were obtained in vivo and ex vivo using a hand-held gamma probe counter and the findings were compared with histological examination. SLN was defined as the node with the highest count rate.

RESULTS

SLNs were identified in 23 of 25 patients (92%) with a total number of 52 SLNs. Seven of 52 (13%) of these SLNs were positive for metastatic involvement after histological and immunohistochemical examination. In two patients (8%), SLNs could not be found. The sensitivity and specificity were 55% and 86% respectively.

CONCLUSIONS

This technic is a good method for identifying the first site of potential nodal metastases of NSCLC. These preliminary results demonstrate this procedure is feasible, but the detection rate has to be improved.

Identification of metastatic nodal disease in a phase 1 dose-escalation trial of intraoperative sentinel lymph node mapping in non-small cell lung cancer using near-infrared imaging

OBJECTIVES

Early-stage non-small cell lung cancer (NSCLC) has a high recurrence rate and poor 5-year survival, particularly if lymph nodes are involved. Our objective was to perform a dose-escalation study to assess safety and feasibility of intraoperative near-infrared (NIR) fluorescence imaging to identify the first tumor-draining lymph nodes (ie, sentinel lymph nodes [SLNs] in patients with NSCLC).

METHODS

A-dose escalation phase 1 clinical trial assessing real-time NIR imaging after peritumoral injection of 3.8 to 2500 μg indocyanine green (ICG) was initiated in patients with suspected stage I/II NSCLC. Visualization of lymphatic migration, SLN identification, and adverse events were recorded.

RESULTS

Thirty-eight patients underwent ICG injection and NIR imaging via thoracotomy (n = 18) or thoracoscopic imaging (n = 20). SLN identification increased with ICG dose, with fewer than 25% SLNs detected in dose cohorts of 600 μg or less versus 89% success at 1000 μg or greater. Twenty-six NIR(+) SLNs were identified in 15 patients, with 7 NIR(+) SLNs (6 patients) harboring metastatic disease on histologic analysis. Metastatic nodal disease was never identified in patients with a histologically negative NIR(+) SLN. No adverse reactions were noted.

CONCLUSIONS

NIR-guided SLN identification with ICG was safe and feasible in this initial dose-escalation trial. ICG doses greater than 1000 μg yielded nearly 90% intrathoracic SLN visualization, with the presence or absence of metastatic disease in the SLN directly correlating with final nodal status of the lymphadenectomy specimen. Further studies are needed to optimize imaging parameters and confirm sensitivity and specificity of SLN mapping in NSCLC using this promising imaging technique.

Accuracy of sentinel node biopsy in the staging of non-small cell lung carcinomas: systematic review and meta-analysis of the literature

BACKGROUND

Not all patients with non-small cell lung carcinoma (NSCLC) have mediastinal lymph node involvement and development of less invasive methods for evaluating mediastinal lymph nodes is important. Sentinel node biopsy has been used for NSCLC since 1999 to decrease the need for mediastinal lymph node dissection. In this review, we searched the literature in this regard and reported the results in a meta-analysis format.

METHODS

Medline, SCOPUS, and ISI web of knowledge were searched using: "(lung AND sentinel)" with no date or language limit. Any study with more than 5 patients and enough information to calculate detection rate and sensitivity was included.

RESULTS

Overall 47 and 43 studies (including subgroups) had the criteria for detection rate and sensitivity pooling respectively. Pooled detection rate was 80.6% [76.8-84%] and pooled sensitivity was 87% [83-90%]. Using radiotracers or both radiotracers and dyes had higher detection rate and sensitivity compared to dye alone. Among studies using radiotracers, highest detection rate was in intra-operative peri-tumoral injection group and highest sensitivity was in peri-tumoral pre-operative injection group. Emerging methods of sentinel node surgery including magnetic materials, fluorescent dyes, CT contrast agents, and carbon nano-particles had promising results.

CONCLUSIONS

Sentinel node mapping using radiotracers is a feasible technique for mediastinal lymph node staging of N0 NSCLC patients. Alternative methods of sentinel node mapping are promising and warrant further studies.

Preclinical study of near-infrared-guided sentinel lymph node mapping of the porcine lung

BACKGROUND

The presence of lymph node metastasis is the most important prognostic factor in early non-small cell lung cancer. Our objective was to develop a rapid, simple, and reliable method for thoracic sentinel lymph node (SLN) identification using near-infrared fluorescence imaging and clinically available contrast agents.

METHODS

Indocyanine green (ICG) reconstituted in saline, human serum albumin, human fresh frozen plasma, and autologous porcine plasma was evaluated for optimal formulation and dosing for SLN within porcine lungs. Animals were imaged using the fluorescence-assisted resection and exploration for surgery imaging system. The SLN identification rate, time to identification and fluorescence intensity of the SLN, bronchus, and background were measured.

RESULTS

The SLN identification rates varied widely, ranging from 33% to 100% as a function of the carrier used for ICG reconstitution. No significant difference was noted in SLN fluorescence intensity; however, bronchial intensity was significantly higher with ICG: albumin, which resulted in the lowest rate of SLN identification. Subsequent evaluation with 125 μM and 250 μM ICG:porcine plasma resulted in identification of strongly fluorescent SLNs, with identification rates of 93% and 100% and median signal-to-background ratios of 8.5 and 12.15, respectively, in less than 2 minutes in situ.

CONCLUSIONS

Near-infrared fluorescence imaging with ICG is a reliable method for SLN mapping in the lung with high sensitivity. Mixing of ICG with plasma resulted in strong SLN fluorescence signal with reliable identification rates.

Mediastinal lymph nodes: ignore? sample? dissect? The role of mediastinal node dissection in the surgical management of primary lung cancer

The role of mediastinal lymph node dissection (MLND) during the resection of non-small-cell lung cancer is still unclear although most surgeons agree that a minimum of hilar and mediastinal nodes must be examined for appropriate pathological staging. Current surgical practices vary from visual inspection of the mediastinum with biopsy of only abnormal looking nodes to systematic mediastinal node sampling which is to the biopsy of lymph nodes from multiple levels whether they appear abnormal or not to MLND which involves the systematic removal of all lymph node bearing tissue from multiple sites unilaterally or bilaterally within the mediastinum. This review article looks at the evidence and arguments in favour of lymphadenectomy, including improved pathological staging, better locoregional control, and ultimately longer disease-free survival and those against which are longer operating time, increased operative morbidity, and lack of evidence for survival benefit.

Developing intrathoracic sentinel lymph node mapping with near-infrared fluorescent imaging in non-small cell lung cancer

With poor survival and high recurrence rates, early-stage lung cancer currently appears to be understaged or undertreated, or both. Although sentinel lymph node biopsy is standard for patients with breast cancer and melanoma, its success has been unreliable in non-small cell lung cancer. Sentinel lymph node biopsy might aid in the identification of lymph nodes at the greatest risk of metastasis and allow for more detailed analysis to select for patients who might benefit from adjuvant therapy. The early results in our recent clinical trial of patients with early-stage lung cancer have suggested that near-infrared imaging might offer a platform for reliable sentinel lymph node identification in these patients.

Impact of nodal status and tumor burden in sentinel lymph nodes on the clinical outcomes of cancer patients

The validation of sentinel lymph node (SLN) concept in melanoma and breast cancer has established a new paradigm in cancer metastasis that, in general, cancer cells spread in a orderly fashion from the primary site to the SLNs in the regional nodal basin and then to the distant sites. In this review article, we examine the development of SLN concept in penile carcinoma, melanoma and breast carcinoma and its application to other solid cancers with emphasis of the relationship between micrometastasis in SLNs and clinical outcomes.

Image-guided sentinel lymph node mapping and nanotechnology-based nodal treatment in lung cancer using invisible near-infrared fluorescent light

Current methods for sentinel lymph node (SLN) mapping and nodal treatment in lung cancer remain inadequate for routine clinical use. In this study, we discuss the potential for using the combination of invisible near-infrared (NIR) fluorescent light and nanotechnology for these applications. NIR fluorescence imaging has recently received significant attention for in vivo imaging applications because of its low tissue autofluorescence, high photon penetration into living tissue, and high signal-to-background ratio. Our large animal in vivo studies have been able to successfully identify SLNs in lung tissue, and several clinical studies have examined the use of NIR fluorescence imaging systems for SLN mapping in breast and gastric cancer. Promising new nanoparticle technologies, when combined with NIR fluorescence imaging, offer the potential for image-guided treatment of lymph nodes at high risk for tumor recurrence. This review provides a theoretic and empiric framework for developing the next generation of diagnostic and therapeutic agents for lung cancer.

Intratumoural chemotherapy of lung cancer for diagnosis and treatment of draining lymph node metastasis

Objectives

Reviewed here is the potential effectiveness of cytotoxic drugs delivered by intratumoural injection into endobronchial tumours through a bronchoscope for the treatment of non-small cell lung cancer and the diagnosis of occult or obvious cancer cell metastasis to mediastinal lymph nodes.

Key findings

Intratumoural lymphatic treatment may be achieved by injection of cisplatin or other cytotoxic drugs into the malignant tissue located in the lumen of the airways or in the peribronchial structures using a needle catheter through a flexible bronchoscope. This procedure is termed endobronchial intratumoural chemotherapy and its use before systemic chemotherapy and/or radiotherapy or surgery may provide a prophylactic or therapeutic treatment for eradication of micrometastases or occult metastases that migrate to the regional lymph nodes draining the tumour area.

Conclusions

To better elucidate the mode of action of direct injection of cytotoxic drugs into tumours, we review the physiology of lymphatic drainage and sentinel lymph node function. In this light, the potential efficacy of intratumoural chemotherapy for prophylaxis and locoregional therapy of cancer metastasis via the sentinel and regional lymph nodes is indicated. Randomized multicenter clinical studies are needed to evaluate this new and safe procedure designed to improve the condition of non-small cell lung cancer patients and prolong their survival.

A comprehensive overview of radioguided surgery using gamma detection probe technology

The concept of radioguided surgery, which was first developed some 60 years ago, involves the use of a radiation detection probe system for the intraoperative detection of radionuclides. The use of gamma detection probe technology in radioguided surgery has tremendously expanded and has evolved into what is now considered an established discipline within the practice of surgery, revolutionizing the surgical management of many malignancies, including breast cancer, melanoma, and colorectal cancer, as well as the surgical management of parathyroid disease. The impact of radioguided surgery on the surgical management of cancer patients includes providing vital and real-time information to the surgeon regarding the location and extent of disease, as well as regarding the assessment of surgical resection margins. Additionally, it has allowed the surgeon to minimize the surgical invasiveness of many diagnostic and therapeutic procedures, while still maintaining maximum benefit to the cancer patient. In the current review, we have attempted to comprehensively evaluate the history, technical aspects, and clinical applications of radioguided surgery using gamma detection probe technology.

VEGF121 promotes lymphangiogenesis in the sentinel lymph nodes of non-small cell lung carcinoma patients

BACKGROUND

The sentinel lymph node (SLN) concept is that lymphatic flux from a primary tumor initially flows into a SLN. The mechanism mediating tumor metastasis within SLNs remains largely unknown; however, primary tumors overexpressing vascular endothelial growth factor (VEGF)-A appear to induce SLN lymphangiogenesis prior to metastasis in animal model. Our aim was to further investigate the capacity of VEGFs to induce lymphangiogenesis within SLNs and to assess their role in SLN metastasis in non-small cell lung carcinoma (NSCLC).

METHODS

Real-time quantitative RT-PCR was used to assess expression of mRNAs encoding several VEGFs (VEGF121, VEGF165, VEGFR1, VEGFR2, VEGFR3, VEGF-C and VEGF-D) in resected lymph node specimens from 35 NSCLC patients, after which we compared their expression SLNs and non-SLNs. In addition, expression of the lymphatic endothelium-specific hyaluronan receptor (LYVE)-1 was used to assess lymphangiogenesis in SLNs and non-SLNs.

RESULTS

Immunohistochemical staining revealed substantial expression of LYVE-1 in SLNs. Moreover, levels LYVE-1 mRNA were significantly higher in SLNs than non-SLNs (P<0.05), as were levels of VEGF121 and VEGFR2 mRNA (P<0.01 and P=0.02, respectively). In addition metastasis-positive SLNs showed significantly higher levels of VEGF121, VEGF-C and VEGF-D mRNA than metastasis-negative SLNs (P<0.001, P=0.01 and P=0.01, respectively), and VEGF121 induced the proliferation of lymphatic endothelial cells (P<0.01).

CONCLUSIONS

Our findings suggest that active lymphangiogenesis is ongoing within SLNs from NSCLC patients, even before metastasis. This lymphangiogenesis may be promoted by upregulation of VEGF121, which may in turn act in part via induction of VEGF-C.

Subpleural injection of tracer improves detection of mediastinal sentinel lymph nodes in non-small cell lung cancer

BACKGROUND

The advantages and disadvantages of various tracer injection protocols for sentinel lymph node (SLN) mapping have been extensively discussed in relation to breast and gastric cancer. But no such discussion has taken place in relation to SLN mapping in non-small cell lung cancer. We therefore studied the effect of two tracer injection protocols on SLN mapping in patients with non-small cell lung cancer; of particular interest was the relationship between subpleural tracer injection and identification of mediastinal SLNs.

METHODS

A quadrant injection group (n=49) received 1.6 ml of ferucarbotran by peritumoral quadrant injection after thoracotomy. In the subpleural injection group, the same amount of ferucarbotran was injected into the peritumoral quadrants plus the subpleural region (n=27). SLNs were then detected intraoperatively by measuring the magnetic force within lymph nodes using a hand-held magnetometer. After completing the SLN mapping, lobectomy and hilar and mediastinal lymph node dissection was performed.

RESULTS

The incidence of mediastinal SLNs was significantly higher in the subpleural injection group (45.4%) than in the quadrant injection group (14.6%) (p=0.007). Moreover, nominal logistic regression analysis revealed subpleural injection to be a significant independent factor contributing to detection of mediastinal SLNs (p=0.024, odds ratio 5.26). In the quadrant injection group, mediastinal lymph node metastasis was detected in two patients thought to have nonmetastatic parenchymal SLNs. By contrast, there were no false-negative cases in the subpleural injection group.

CONCLUSION

Subpleural tracer injection significantly improves detection of mediastinal SLNs in non-small cell lung cancer.

Sentinel node identification in clinical stage Ia non-small cell lung cancer by a combined single photon emission computed tomography/computed tomography system

OBJECTIVE

A gamma probe can identify sentinel nodes before nodal dissection in the mediastinum but not in the hilum, owing to high radioactivity from primary tumors. We evaluated the utility of fused single photon emission computed tomography/computed tomography (SPECT/CT) images for the identification of sentinel nodes in the hilum for patients with clinical stage Ia non-small cell lung cancer.

METHODS

Technetium-99m tin colloid was injected into the peritumoral region approximately 18 hours before surgery in 63 patients with clinical stage Ia non-small cell lung cancer. On the morning of the operation, approximately 16 hours after administration of tin colloid, sentinel nodes were identified by fused SPECT/CT; this was followed by intraoperative sentinel node identification in the dissected lymph nodes by gamma probe. Because the gamma probe is a standard method for sentinel node identification, the sensitivity of fused SPECT/CT images was examined on the basis of the data of the gamma probe.

RESULTS

Fused SPECT/CT images could identify sentinel nodes at segmental and lobar lymph nodes with a sensitivity of 0.87 and 0.74, both of which were significantly higher than 0.40 in the mediastinum (P < .001 and P = .012, respectively). In 5 patients with pathologic N1 or N2 disease, both SPECT/CT and the gamma probe could identify sentinel nodes with metastases.

CONCLUSIONS

SPECT/CT could identify sentinel nodes of the hilum especially in segmental and lobar lymph nodes but not in the mediastinum. Because the gamma probe can identify sentinel nodes before nodal dissection in the mediastinum but not in the hilum, a combination of SPECT/CT and the gamma probe can be used to identify sentinel nodes before nodal dissection in both the hilum and the mediastinum, which will enable sentinel node navigation surgery in non-small cell lung cancer.

Intraoperative, Radio-Guided Sentinel Lymph Node Mapping in 110 Nonsmall Cell Lung Cancer Patients

BACKGROUND

Sentinel lymph node identification has been tested in lung cancer patients with conflicting results. The present study was designed to assess the sensitivity, negative predictive value, and accuracy of intraoperative sentinel lymph node mapping by means of a radio-guided method in patients with nonsmall cell lung cancer to find the most appropriate definition of sentinel lymph node and to evaluate the usefulness of different particle sizes of radiocolloid.

METHODS

One hundred ten patients with clinically N0 nonsmall cell lung cancer were enrolled in the pilot study of intraoperative sentinel node identification. Four quadrants of the peritumoral tissue were injected with 2 mL of 0.5 mCi technetium-99m suspension. Four radiocolloids of different particle size were used. After complete lymphadenectomy, all resected lymph nodes were examined with hematoxylin-eosin staining. All sentinel nodes negative for metastases by routine staining were searched further for metastatic deposits with both serial sections and immunohistochemistry for cytokeratins.

RESULTS

The radio-guided method had a high identification rate, a high sensitivity, and a high negative predictive value (100%, 87%, and 93%, respectively) when immunohistochemistry was considered. When standard hematoxylin and eosin staining was applied, sensitivity and negative predictive value of sentinel lymph node labeling was lower (74% and 89%, respectively). No significant differences were found in either the sensitivity or negative predictive value among the colloid solutions of different particle size used in radio labeling, although smaller particles have shown a tendency to produce better results.

CONCLUSIONS

The radio-guided technique provides efficient sentinel lymph node identification in lung cancer. Further studies are warranted to confirm the clinical utility of this strategy.

Blue-dye intraoperative sentinel lymph node mapping in early non-small cell lung cancer

AIMS

The blue-dye staining method of sentinel lymph node identification in lung cancer patients has been scarcely reported. The study was designed to assess the sensitivity, accuracy and negative predictive value (NPV) of intraoperative sentinel lymph node mapping in patients with non-small cell lung cancer by means of staining with colloid or water solution of blue dye.

PATIENTS AND METHODS

One hundred and ten patients with clinically confirmed NO non-small cell lung cancer were enrolled into prospective study of intraoperative sentinel node identification. Four quadrants of the peritumoral tissue were injected with 4 ml of blue dye. After complete lymphadenectomy, all resected lymph nodes were examined with conventional hematoxylin-eosine staining. All negative sentinel nodes were searched for metastatic deposits with both serial sections and immunohistochemistry for cytokeratines.

RESULTS

The blue-dye technique was characterized by unacceptably low sentinel node identification rate (IR) and low sensitivity (27% and 67% respectively). No significant differences were found in either the sensitivity or NPV among the colloid or water solutions of the blue dye applied. Although patent blue (colloid) was superior to water solution of methylene blue in identifying sentinel lymph node (identification rate 36% and 22% respectively) the sensitivity and NPV were lower (63% and 80% for patent blue and 75% and 92% for methylene blue respectively).

CONCLUSION

The blue-dye staining method of sentinel node identification in non-small cell lung cancer patients is inadequate and should not be recommended for clinical use.

Limited mediastinal lymph node dissection for non-small cell lung cancer according to intraoperative histologic examinations

BACKGROUND

Although radioisotopic procedures are commonly used to detect sentinel lymph nodes in breast cancer surgery, these procedures are often problematic and not necessarily suitable for lung cancer surgery.

METHODS

Our previous study revealed that the mediastinal sentinel lymph node, defined as the regional mediastinal lymph node, consisted of nodes 2, 3, or 4 in right upper lobe cancers; 3, 7, or 8 in right lower lobe cancers; 4, 5, or 7 in left upper lobe cancers; and 4, 7, or 8 in left lower lobe cancers. On the basis of these findings, we pathologically investigated one representative lymph node at each of the 3 levels dissected during surgical intervention in 69 patients with non-small cell lung cancer from September 1993 through December 2002. Fifty-eight patients with lung cancer underwent lobectomies with limited mediastinal lymph node dissection according to this strategy.

RESULTS

Mediastinal lymph node recurrence was observed in only one patient during 41 +/- 25 months (maximum, 98 months) of follow-up. The cancer-specific 5-year survivals were 96.6% in patients with pathologic stage IA disease (n = 31) and 67.4% in patients with stage IB disease (n = 16).

CONCLUSION

These results suggested that limited mediastinal lymph node dissection is applicable to patients with non-small cell lung cancer whose regional mediastinal lymph nodes are not metastatic.

Sentinel lymph node mapping and molecular staging in nonsmall cell lung carcinoma

BACKGROUND

Lymph node (LN) involvement predicts recurrence in patients who have undergone resection of apparently localized nonsmall cell lung carcinoma (NSCLC). Standard detection methods for LN disease have a low sensitivity, and many patients with apparent N0 disease status develop recurrent disease. Molecular techniques can improve the detection of micrometastases, whereas sentinel lymph node (SLN) mapping can indicate which LN may contain micrometastases. These methods, although potentially complementary, have not, to the authors' knowledge, been used together previously.

METHODS

The authors used SLN mapping and molecular staging to improve the detection of LN micrometastases in patients with NSCLC. Reverse transcriptase-polymerase chain reaction (RT-PCR) analysis for cytokeratin-7 (CK7), expressed both in normal lung and in malignant lung, was used to identify tumor-derived material in LN.

RESULTS

SLN mapping was performed in 13 patients, with 1-3 SLNs identified in each patient, and sufficient RNA for RT-PCR was obtained in 12 of these 13 patients. Eleven of 12 tumors expressed CK7. Overall, 32 LNs were positive for CK7, including 13 of 21 SLNs. Ten of 11 patients with evaluable SLNs had at least 1 CK7-positive SLN. Routine pathology showed Stage I disease in eight patients, T3N0 disease in one patient, and LN-positive disease in two patients. Of the nine patients with N0 disease according to routine pathology that was evaluable by RT-PCR, eight patients were upstaged by this technique. All patients with positive LN status by routine pathology who were evaluable by RT-PCR analysis had positive RT-PCR results.

CONCLUSIONS

LN micrometastases were common in resected NSCLC, including patients with N0 disease according to routine pathology. SLN mapping was useful for identifying disease-containing LNs. This approach may be useful for stratifying histologically N0 patients into higher risk and lower risk groups.

Intraoperative sentinel lymph node mapping of the lung using near-infrared fluorescent quantum dots

BACKGROUND

The presence of lymph node metastases is an important prognostic marker with regard to non-small-cell lung cancer (NSCLC). Assessment of the sentinel lymph node (SLN) for the presence of tumor may improve staging. Our objective was to develop an optical noninvasive imaging tool that would permit intraoperative SLN mapping and provide real-time visual feedback for image-guided localization and resection.

METHODS

Invisible near-infrared (NIR) light penetrates relatively deeply into tissue and background autofluorescence is low. We have developed a NIR fluorescence imaging system that simultaneously displays color video and NIR images of the surgical field. We recently engineered 15 nm nonradioactive NIR fluorescent quantum dots (QDs) as optimal lymphotrophic optical probes. The introduction of these QDs into lung tissue allows real-time visualization of draining lymphatic channels and nodes.

RESULTS

In 12 Yorkshire pigs (mean weight 35 kg) we demonstrated that 200 pmol of NIR QDs injected into lobar parenchyma accurately maps lymphatic drainage and the SLN. All SLNs were strongly fluorescent and easily visualized within 5 minutes of injection. In 14 separate injections QDs localized to a mediastinal node, whereas in 2 injections QDs localized to a hilar intraparenchymal node. Histologic analysis in all cases confirmed the presence of nodal tissue.

CONCLUSIONS

We report a highly sensitive rapid technique for SLN mapping of the lung. This technique permits precise real-time imaging and therefore overcomes many limitations of currently available techniques.

Mediastinal Staging 2005: Pictures, Scopes, and Scalpels

Staging of the mediastinum for lung cancer has matured dramatically with the advent of newer technologies in imaging and endoscopic surveillance. Some of these technologies such as positron emission tomography (PET) scanning are becoming mainstream in the evaluation of patients with clinically suspicious mediastinal disease as seen on computed tomography (CT), while others such as endobronchial ultrasound are reserved for specialty expertise and await validation. While much improvement has been made in the accurate preoperative staging of patients having surgery as the primary modality in lung cancer, controversy exists regarding the restaging of locally advanced cases after induction chemotherapy or chemoradiotherapy. A major concentration on these restaging issues is warranted since it is now generally agreed that sterilization of the mediastinum after induction therapy has an impact on the prognosis of patients with stage IIIA disease, and accurate staging after therapy may rationally guide diverse therapeutic interventions in these patients.

Feasibility of the Detection of the Sentinel Lymph Node in Peripheral Non-small Cell Lung Cancer With Radio Isotopic and Blue Dye Techniques

STUDY OBJECTIVES

The objective of this study was to evaluate the feasibility of the sentinel lymph node (SLN) biopsy in peripheral clinically stage I or II non-small cell lung cancer (NSCLC) using (99m)Tc colloid and a hand-held gamma detection probe, associated with a blue dye technique.

DESIGN

Prospective study.

SETTING

Royal Brompton Hospital, London, UK; and Hopital Nord, Saint Etienne, France.

METHODS

After thoracotomy, a total of 2 mL patent blue dye mixed with 1,600 muCi (99m)Tc-albumin or (99m)Tc-colloid was injected into each quadrant of lung tissue immediately surrounding the tumor. Routine lymphadenectomy was carried out. The first lymph nodes to stain blue or radioactive, if any, were considered SLNs.

RESULTS

Twenty-four patients were evaluated. We successfully identified 17 SLNs in 13 patients (detection rate, 54.2%). Mean time from injection to identification of SLNs was 18 min (range, 5 to 30 min). In nine cases, the SLN was blue and radioactive, in six cases only blue, and in two cases only radioactive. The pathologic status of the SLN reflected the pathologic status of other nodes of the routine lymphadenectomy except one case of false-negative SLN (14%). Four SLNs were in N2 stations (23.5%).

CONCLUSIONS

The sentinel node mapping in NSCLC with blue dye and radioisotopic techniques is feasible, but the detection rate has to be improved. This technique is an accurate method of identifying the first node draining a tumor, although it is not yet sufficiently sensitive to have a role in reducing the extent of nodal dissection.

In vivo identification of sentinel lymph nodes for clinical stage I non-small cell lung cancer for abbreviation of mediastinal lymph node dissection

BACKGROUND

We previously reported that an identification of sentinel lymph node (SN) with a techenetium-99m (99mTc) tin colloid by ex vivo counting, i.e. the radio-activity of dissected lymph nodes, was a reliable method of establishing the first site of nodal metastasis in non-small cell lung cancer [J. Thorac. Cardiovasc. Surg. 124(2002)486]. However, for SN navigation surgery, SN should be identified before lymph node dissection (in vivo) but not after that (ex vivo). In order to reduce mediastinal lymph node dissection for clinical stage I non-small cell lung cancer (NSCLC) by SN navigation surgery, the SN identifications for hilar lymph nodes by ex vivo counting, and for mediastinal lymph nodes by in vivo, were evaluated.

METHODS

Intra-operative SN identification using 99mTc tin colloid was conducted on 104 patients with clinical stage I NSCLC who had had major lung resections with mediastinal lymph node dissections. The hilar SNs were identified by ex vivo counting (after lung resection) and the mediastinal SNs were identified by in vivo counting (before lymph node dissection). To evaluate the accuracy of mediastinal SN identification by in vivo counting, it was compared with the data by ex vivo counting.

RESULTS

SNs were identified in 84 patients (81%). SNs were identified at the hilum by ex vivo counting in 78 patients (93%) and at the mediastinum by in vivo counting in 40 patients (48%). While 15 patients had lymph node metastases, i.e. N1 in six and N2 in nine, the SNs could be found to have metastases during operation in 13 of the 15 patients (87%). The in vivo counting of the mediastinum missed out the mediastinal SNs identified by ex vivo counting in four of the 84 patients (5%).

CONCLUSION

If the hilar SNs identified by ex vivo counting and the mediastinal SNs identified by in vivo counting had no metastases, then mediastinal lymph node dissection could be abbreviated for patients with clinical stage I NSCLC.

Sentinel node mapping in lung cancer

Lymph node metastases are the most significant prognostic factor in localized non-small-cell lung cancer (NSCLC). Nodal micrometastases may not be detected with current standard histologic methods. We review our experience with intraoperative injection of radioisotope, the current state of the technique, and the experience of other groups with alternate methods and tracers.

Computed Tomography Lymphography With Intrapulmonary Injection of Iopamidol for Sentinel Lymph Node Localization

PURPOSE

Experimental and clinical evaluation of the potential utility of indirect computed tomographic lymphography (CT-LG) with intrapulmonary injection of iopamidol for preoperative localization of sentinel lymph node station in non-small cell lung cancer.

METHODS

CT-LG with intrapulmonary injection of 0.5 mL of undiluted iopamidol was performed in 10 dogs using a multidetector-row CT unit, followed by postmortem examination of enhanced lymph nodes in 5 of these dogs. The CT-LG with peritumoral injection of 1 mL of the contrast agent was also performed in 9 patients with non-small cell lung cancer without lymphadenopathy. At surgery, enhanced lymph nodes were resected under CT-LG guide, followed by standard lymph node dissection with macroscopic and histologic examination. A significant enhancement of lymph nodes was determined when CT attenuation value was increased with 30 Hounsfield units (HU) compared with precontrast images.

RESULTS

CT-LG visualized a total of 15 enhanced lymph nodes (on average, 1.5 nodes per animal) within 2 minutes after contrast injection in the 10 dogs, with average size of 6.7+/- 1.9 mm and average maximum CT attenuation of 149 +/- 41 HU. All the 8 enhanced nodes in 5 dogs were found in the appropriate anatomic locations in postmortem examinations. Without noticeable complications, CT-LG visualized 30 ipsilateral intrathoracic lymph nodes including 19 hilar/pulmonary and 11 mediastinal nodes in the 9 patients (on average, 2.2 hilar/pulmonary and 1.1 mediastinal nodes per patient) within 2 minutes after contrast injection, with average size of 4.7+/- 0.4 mm and average maximum CT attenuation of 134 +/- 52 HU. At surgery, all these enhanced nodes could be accurately found and resected under CT-LG guidance. Metastasis was not evident in either of these enhanced lymph nodes or the remaining distant nodes in all patients.

CONCLUSION

Quick and accurate localization of sentinel lymph node station on detailed underlying lung anatomy by using indirect CT-LG may be of value to guide selective lymph node dissection for minimally invasive surgery in non-small cell lung cancer.

Standard immunostains for melanoma in sentinel lymph node specimens: which ones are most useful?

BACKGROUND

Sentinel lymph node (SLN) biopsy in melanoma is an increasingly used procedure. Pathologic evaluation of SLNs using immunohistochemistry improves diagnostic accuracy, yet no universally accepted standard protocol for pathologic processing of SLNs exists.

OBJECTIVE

The primary purpose of this study was to evaluate our experience with the sensitivity of the immunostains S-100, HMB-45, and Melan-A for SLN biopsy.

METHODS

Ninety-nine positive SLNs from 72 patients were retrospectively reviewed for the presence of microscopic metastatic melanoma on hematoxylin and eosin (H&E), S-100, HMB-45, and Melan-A stained sections and sensitivities of each immunohistochemical stain were determined.

RESULTS

The sensitivities of S-100, HMB-45, and Melan-A were 97%, 75%, and 96% respectively.

CONCLUSION

Given the lower sensitivity of HMB-45, our practice for evaluation of SLN biopsy specimens was modified using combinations of H&E, S-100, and Melan-A without HMB-45. If the H&E sections are negative or equivocal for metastatic melanoma, immunohistochemistry staining with S-100 protein and Melan-A is performed. New and improved protocols will undoubtedly be forthcoming as the field advances.

New fields of application of the sentinel lymph node biopsy in the pathologic staging of solid neoplasms: review of literature and surgical perspectives

Sentinel lymph node (sN) biopsy has gained special attention among surgical and medical oncologists as it represents an accepted technique for detecting occult nodal disease in regional lymph nodes of patients with melanoma and breast cancer. The histopathologic examination of the sN may well predict regional lymph node status in order to define the most suitable loco-regional and systemic treatment. Recently, this technique has also been applied to other solid tumor types such as gynecologic and urologic malignancies, squamous head and neck cancer, thyroid cancer, non-small-cell lung cancer, Merkel cell carcinoma, and gastric cancer. The aim of this literature review is to define the rationale of sN biopsy in these tumor sites, the most effective procedure for sN detection, and the accuracy of the sN in predicting regional nodal status, as well as the surgical perspectives of sN biopsy application.

Radioisotope lymph node mapping in nonsmall cell lung cancer: can it be applicable for sentinel node biopsy?

BACKGROUND

Previous studies on intrathoracic lymph node mapping have focused on the validity of a sentinel node concept, but not on the usefulness for sentinel node biopsy.

METHODS

The subjects were 15 patients clinically diagnosed with N0 nonsmall cell lung cancer. Technetium-99m tin colloid was injected into the peritumoral area 1 day preoperatively and a time course of tracer migration was monitored by scintigraphy. A hand-held gamma probe counter was used to count the intrathoracic lymph node stations. Resected nodes were also counted to assess the accuracy of the intrathoracic counting.

RESULTS

Serial scintigraphies showed that the tracer migrated through airways and the appearance resembled hot nodes. On intrathoracic counting, 50% of the nodal stations appeared positive; however, only 23% of these apparently positive nodal stations were ultimately shown to be truly radioactive. The true positive and true negative rates of detecting intrathoracic hot nodes were 100% and 56%, respectively. Because the counts of the nodal stations could include the counts from the hot primary tumor ("shine-through") or airway radioactivity, legitimate hot nodes were identified after dissecting all the apparently positive nodal stations. Two of the 9 patients in whom hot nodes were identified had nodal metastatic disease and actually had tumor cells within the hot nodes. The only complication related to the preoperative injection of technetium-99m was a minor pneumothorax.

CONCLUSIONS

Although radioisotope intrathoracic lymph node mapping is safe, it appears to be unsuitable for sentinel node biopsy because shine-through and the airway-migrated radioactive tracer complicated the intrathoracic counting. Only serial scintigraphy could distinguish hot nodes from airway migration.

Preoperative imaging of the lung sentinel lymphatic basin with computed tomographic lymphography: a preliminary study

BACKGROUND

Preoperative localization of the sentinel node basin would guide selective lymph node dissection. We tried to identify these nodal stations with indirect computed tomographic lymphography using a conventional extracellular contrast agent, iopamidol.

METHODS

Eleven consecutive patients scheduled to undergo anatomic resection of suspected lung cancer, without lymphadenopathy, were given a peritumoral injection of undiluted iopamidol under computed tomography guidance, and lymphatic migration was assessed by multidetector-row helical computed tomography.

RESULTS

There were no complications such as bleeding, pneumothorax, or allergic reactions. Enhanced nodes were detected in all but 1 patient who had diffuse lymph nodal calcification. Enhanced nodes were identified at 32 ipsilateral intrathoracic nodal stations (20 hilar stations and 12 mediastinal stations). The average length of the longer axis of the enhanced nodes was 4.8 mm (range, 3 to 8 mm), and the average attenuation of the enhanced nodes was 132 (range, 46 to 261) Hounsfield units. In 9 patients with confirmed lung cancer, enhanced nodes appeared at 26 nodal stations, and all apparent enhanced nodes were identified as actual lymph nodes at appropriate position during lymphadenectomy. None of the resected lymph nodes had metastatic involvement.

CONCLUSIONS

Indirect computed tomographic lymphography with the peritumoral injection of iopamidol effectively depicts the drainage nodes unless they are diffusely calcified. Although further study is required, this method could guide selective lymph node dissection.

Potential of Magnetic Resonance Lymphography With Intrapulmonary Injection of Gadopentetate Dimeglumine for Visualization of the Pulmonary Lymphatic Basin in Dogs

PURPOSE

To evaluate a new approach of magnetic resonance (MR) lymphography with intraalveolar injection of a conventional extracellular contrast agent (gadopentetate dimeglumine) for imaging lymphatic basin draining from specific portions of the lung.

METHODS

Three-dimensional T1-weighted spoiled gradient-recalled echo MR sequence images were acquired serially before and for 40 minutes after intraalveolar injection of gadopentetate dimeglumine in a total of 14 anesthetized beagle dogs. Six of these dogs received 1 mL undiluted and low-concentration (75%) contrast agent into the same portion of the right caudal lobe during a 7-day interval. In all dogs, including these 6 dogs, MR lymphography was repeated with injection of the low-concentration contrast agent into different lung regions at 7-day intervals to evaluate the differences of the visualized draining lymphatic station. Lymphatic enhancement was quantified by percent increases of signal intensity against precontrast. Postmortem examination of the lymphatic anatomy was performed in 7 of these animals.

RESULTS

In all dogs, the lymphatic station draining from the injection sites was visualized within 5 minutes after contrast injection. The maximum percent increase of signal intensity of the same middle tracheobronchial lymph nodes was significantly greater with a low-concentration (75%) contrast agent than with an undiluted one in the same 6 dogs (n = 6, 247.6 +/- 30.5% vs. 204.2 +/- 33.8%; P < 0.01). Different lymphatic stations draining from the different injection sites were visualized in all dogs. In a total of 12 MR studies that showed extended nodal enhancement after injection of the low-concentration contrast agent, the enhancement peak of the most proximal nodes (n = 12) from the injection sites appeared earlier than that of their distant nodes (n = 12), with a maximum percent increase of signal intensity of 249.8 +/- 42.4%. The visualized lymph nodes were found in the appropriate locations postmortem, with significant correlation for nodal sizes (r = 0.965; P < 0.0001).

CONCLUSION

MR lymphography with low-concentration gadopentetate dimeglumine can quickly and sufficiently visualize the drainage lymphatic station from specific lung portions, and may have the potential of sentinel node mapping in lung cancer.

Effect of radioisotope sentinel node mapping in patients with cT1 N0 M0 lung cancer

BACKGROUND

Application of the sentinel node concept to lung cancer is still controversial. Patients with peripheral small lung cancers would gain the most benefit from this concept, if it were valid. We sought to determine whether it is possible to choose between limited lymph node sampling and systematic lymphadenectomy from the distribution of sentinel lymph nodes in patients with node-negative disease on the basis of imaging.

METHODS

Sixty-five consecutive patients with cT1 N0 M0 non-small cell lung cancer were enrolled. A radioisotope tracer (4 mCi of technetium-99m tin colloid, 2.0 mL) was injected in the vicinity of the tumor before surgical intervention with computed tomographic guidance. The radioactivity of each resected lymph node was measured separately with a hand-held gamma probe after complete tumor resection. Sentinel nodes were identified, and the accuracy of sentinel node mapping was examined. Whether the location of the sentinel node depended on the site of the primary tumor was also examined.

RESULTS

Of the 65 patients, 3 were excluded because of the final pathologic results. Successful radionuclide migration occurred in 39 (62.9%) of the 62 patients. There was 1 (2.6%) false-negative result among 39 patients with a sentinel node, and therefore the sensitivity was 90%, and the specificity was 100%. The most common sentinel lymph nodes were at level 12 (46.7%), followed by level 11 (18.3%), the mediastinum (16.7%), and level 10 (11.7%).

CONCLUSION

The sentinel node concept is valid in patients with cT1 N0 M0 lung cancer. The lobar lymph nodes were identified as sentinel nodes more frequently than other lymph nodes. We need to make further efforts to increase the sentinel node identification rate. However, we believe that if sentinel nodes are identified, sentinel node mapping can allow the accurate intraoperative diagnosis of pathologic N0 status in patients with cT1 N0 M0 lung cancer.

Pulmonary carcinoid tumors

Carcinoid tumors of the lung are an uncommon group of neoplasms of neuroendocrine origin. Pulmonary carcinoid tumors are typically benign and slow growing. However, more aggressive subtypes may develop early nodal and distant metastases. Although several histologic classification strategies have been proposed to distinguish benign from more aggressive subtypes, the lack of uniformity in terminology has resulted in increased ambiguity and confusion. Because these tumors are generally resistant to chemotherapy, complete surgical resection is the primary form of therapy. Long-term survival for patients with typical carcinoid is excellent but is decreased in those with the atypical subtype. Complete tumor resection with preservation of uninvolved pulmonary parenchyma remains the fundamental goal in the surgical treatment of this unusual clinical entity.