Natural History of Pulmonary Subsolid Nodules: A Prospective Multicenter Study

Malignancy estimation of Lung-RADS criteria for subsolid nodules on CT: accuracy of low and high risk spectrum when using NLST nodules

Purpose

Lung-RADS proposes malignancy probabilities for categories 2 (<1%) and 4B (>15%). The purpose of this study was to quantify and compare malignancy rates for Lung-RADS 2 and 4B subsolid nodules (SSNs) on a nodule base.

Methods

We identified all baseline SSNs eligible for Lung-RADS 2 and 4B in the National Lung Screening Trial (NLST) database. Solid cores and nodule locations were annotated using in-house software. Malignant SSNs were identified by an experienced radiologist using NLST information. Malignancy rates and percentages of persistence were calculated.

Results

Of the Lung-RADS 2SSNs, 94.3% (1790/1897) could be located on chest CTs. Likewise, 95.1% (331/348) of part-solid nodules ≥6 mm in diameter could be located. Of these, 120 had a solid core ≥8 mm, corresponding to category 4B. Category 2 SSNs showed a malignancy rate of 2.5%, exceeding slightly the proposed rate of <1%. Category 4B SSNs showed a malignancy rate of 23.9%. In both categories one third of benign lesions were transient.

Conclusion

Malignancy probabilities for Lung-RADS 2 and 4B generally match malignancy rates in SSNs. An option to include also category 2 SSNs for upgrade to 4X designed for suspicious nodules might be useful in the future. Integration of short-term follow-up to confirm persistence would prevent unnecessary invasive work-up in 4B SSNs.

Key points

• Malignancy probabilities for Lung-RADS 2/4B generally match malignancy risks in SSNs.

• Transient rate between low-risk Lung-RADS 2 and high-risk 4B lesions were similar.

• Upgrade of highly suspicious Lung-RADS 2 SSNs to Lung-RADS 4X might be useful.

• Up to one third of the benign high-risk Lung-RADS 4B lesions were transient.

• Short-term follow-up confirming persistence would avoid unnecessary invasive work-up of 4B lesions.

Whack-a-mole strategy for multifocal ground glass opacities of the lung

Ground glass opacity (GGO) is a good prognostic indicator for lung cancer and is useful for physicians to predict prognosis. Due to recent advances in computed tomography (CT), the chance to encounter GGO is rapidly increasing in clinical practice. Based on the studies on radiological pathological correlation, GGO represents pathological lepidic growth and consolidation on CT represents pathologically invasive components. Thus, consolidation tumor ratio 0.5 or less means pathological less invasiveness for lung cancer. Not a few studies have shown that sublobar resection is equivalent to lobectomy for radiological early lung cancers. Additionally, observation of GGO is one of the options for physicians. Indication of surgical intervention remains unclear. Physician observing GGO in practice should know the natural history of GGO to reach an optimal treatment decision. For multifocal GGO lesions clinical management is surely challenging. Whack-a-mole strategy, which means sublobar resection for radiological invasive cancer is one of the most promising strategies for such lesions.

Non-small cell lung cancer: the new T1 categories

Recently, major changes have occurred in the staging, diagnosis, and treatment of early stage lung cancer. By screening high-risk populations, we are now able to detect lung cancers at an early stage, but the false-positive rate is high. A new pathological classification was published in 2011 and fully incorporated in the 2015 World Health Organisation (WHO) Classification of Tumours of the Lung, Pleura, Thymus, and Heart. The new eighth edition of the tumour-node-metastasis (TNM) staging system has been fully published and will be in use from January 2017. T1 lesions are subdivided into T1a, T1b, and T1c lesions corresponding to lung cancers up to 10 mm, between 11 and 20 mm, and between 21 and 30 mm, respectively. To determine the size, only the solid part on computed tomographic scanning of the chest and the invasive part on pathological examination will be considered. Prognosis is significantly better for the smallest lesions. For some specific subgroups, sublobar resection may be oncologically valid and yield good long-term outcome, but the results of recently performed randomised trials are awaited.

Single-stage nonintubated uniportal thoracoscopic resection of synchronous bilateral pulmonary nodules after coil labeling: A case report and literature review

RATIONALE

Preoperative localization of small pulmonary nodules is essential for precise resection, besides, the optimal treatment for pulmonary nodules is controversial and the prognosis without surgery is uncertain.

PATIENT CONCERNS

Herein we present a patient with compromised pulmonary function harboring synchronous triple ground-glass nodules located separately in different pulmonary lobes.

DIAGNOSES

The pathological diagnosis of the nodules were chronic inflammation, inflammatory pseudotumor and atypical adenomatous hyperplasia, respectively.

INTERVENTIONS

The patient underwent single-stage, non-intubated thoracoscopic pulmonary wedge resection after computed tomography-guided coil labeling of the nodules.

OUTCOMES

The postoperative recovery was encouragingly fast without obvious complications.

LESSONS

Non-intubated thoracoscopic pulmonary wedge resection is feasible for patients with compromised lung function, meanwhile, preoperative coil labeling of small nodules is reliable.

Lung Cancers Manifesting as Part-Solid Nodules in the National Lung Screening Trial

OBJECTIVE

The objective of our study was to determine how often death occurred from lung cancers that manifested as part-solid nodules in the National Lung Screening Trial (NLST).

MATERIALS AND METHODS

NLST radiologists classified nodules as solid, ground-glass, or mixed. All lung cancers classified as mixed nodules by NLST radiologists were reviewed by four experienced radiologists and reclassified as solid, nonsolid, or part-solid nodules. When possible, volume doubling times (VDTs) were calculated separately for the entire nodule and for the solid component of the nodule.

RESULTS

Of 88 screening-diagnosed lung cancer cases identified by the NLST radiologists as mixed nodules, study radiologists confirmed that 19 were part-solid nodules. All the part-solid nodules were present at baseline (time 0), and none of the patients with a part-solid nodule had lymph node enlargement at CT before diagnosis or metastases at resection. Multilobar stage IV (T4N0M1) bronchioloalveolar carcinoma was diagnosed in one patient 25.0 months after study randomization, and the patient died 67.9 months after randomization. All 18 patients with a solitary or dominant part-solid nodule underwent surgery, and none died of lung cancer. From randomization, the average time to diagnosis was 18.6 months and the average time of follow-up was 79.2 months. On the last CT examination performed before diagnosis, the average size of the solid component of the part-solid nodules was 9.2 mm (SD, 4.9); the solid component was larger than 10 mm in five patients. The median VDT based on the entire nodule was 476 days, and the median VDT based on the solid component alone was 240 days.

CONCLUSION

None of the patients with lung cancer manifesting as a solitary or dominant part-solid nodule had lymph node enlargement or metastases at pathology, and none died of lung cancer within the follow-up time of the NLST.