Clinical impact and utility of positron emission tomography on occult lymph node metastasis and survival: radical surgery for stage I lung cancer.

OBJECTIVE The surgical result of early-staged lung cancer is not satisfactory due to unexpected postoperative lymph node metastasis and recurrence. This study aimed to investigate which preoperative factors-including the standard uptake value max (SUVmax) of positron emission tomography-could predict occult lymph node metastasis and survival. METHODS We retrospectively analyzed data from 598 patients with clinical stage I lung cancer who underwent surgery, and examined their preoperative clinical characteristics. RESULTS A total of 1586 patients had surgery for primary lung cancer between 2006 and 2019; 598 patients with clinical stage I lung cancer were the study inclusion; occult lymph node metastasis was detected in 102 (17.1%). Univariable and multivariable analyses showed that SUVmax ≥ 3 (P   5 (P = 0.03) were associated with significant risk factors rated (%) for occult lymph node metastasis, as follows: high-risk group (three factors), moderate-risk group (two factors) and low-risk group (one factor or none) corresponding to 32.2 (28/87), 22.8 (41/180) and 7.3 (19/262), respectively (P < 0.001). The 5-year overall survival rates (%) of patients without lymph node metastasis holding SUVmax 6 or over were as poor as those of patients with lymph node metastasis (72.0% vs 64.1%; P = 0.56). CONCLUSIONS We might consider wedge resection or segmentectomy, omitting lymphadenectomy, for the low-risk group; adjuvant therapy is indicated for patients without lymph node metastasis having SUVmax 6 or over.