Clinical Predictors of Nodal Metastases in Peripherally Clinical T1a N0 Non-Small Cell Lung Cancer.

BACKGROUND

Despite the relatively high sensitivity of fluorodeoxyglucose-positron emission tomography (PET) and computed tomography (CT) scans used for staging of non-small cell lung cancer (NSCLC), a subset of patients with peripherally located clinical T1a N0 will be upstaged due to pathologic nodal disease. It is important to study this risk of upstaging, especially if local treatments, such as wedge resection or stereotactic body radiation therapy, are potential treatment modalities. Our aim was to determine the rate of pathologic N1/N2 disease in peripherally located clinical T1a N0 NSCLC and predictive factors for nodal metastasis.

METHODS

A retrospective review of a prospective database (2000 to 2015) identified 1,342 patients with clinical T1a N0 NSCLC, and 914 (68%) underwent lobectomy. Among this group, 449 patients had peripherally located tumors and were deemed node negative by fluorodeoxyglucose-PET/CT scan. The relationship between clinicopathologic features and the PET maximal-standardized uptake value (SUVmax) of the primary tumor was investigated. Predictors for nodal metastasis were determined by multivariable logistic regression analysis. The receiver operating characteristic curve was used to assess the cutoff value of PET-SUVmax on the incidence of nodal metastasis.

RESULTS

Nodal metastasis was detected in 9.6% (43 of 449) of the patients: 4.5% (n = 20) had pN1 and 5.1% (n = 23) had pN2 metastasis. The relationship between SUVmax and development of pathologic nodal metastasis was calculated using the receiver operating characteristic curve with cutoff point at SUVmax of 3.3. In multivariable analysis, PET-SUVmax exceeding 3.3 was the only independent predictor for N1/N2 metastasis (p = 0.016). Disease-free survival showed a trend of poor survival for patients with nodal metastasis (p = 0.068).

CONCLUSIONS

High PET-SUVmax of the primary tumor is associated with elevated risk of nodal disease for peripheral T1a N0 NSCLC patients. Further diagnostic procedures, such as endobronchial ultrasound, may be required, especially if wedge resection or stereotactic body radiation therapy are being considered.