Comparison of clinicopathological characteristics of different categories of MPLCComparison of multifocal GG/L nodules and SPLC

We compared the clinicopathological features of 139 multifocal GG/L nodule patients and 63 SPLC patients (Table 2). The results showed that compared with SPLC patients, patients with multifocal GG/L nodules were more likely to be women and nonsmokers, to have more sMPLCs and early stage tumors, to have more unresected nodules, to be more likely to undergo VATS and sublobectomy surgery, to be asymptomatic and to undergo a one-time operation (P < 0.05).

Table 2 Comparison of multifocal GG/L nodules and second primary lung cancerComparison of sMPLC and mMPLC

There were 171 sMPLC and 31 mMPLC patients included in this study. The clinicopathological features of the two groups were compared; the results showed that compared with the mMPLC group, the sMPLC group had a higher incidence in women, nonsmokers and nondrinkers, more GG/L type tumors, more ipsilateral tumors, lower patient BMI, more people without a personal malignant tumor history, and more people who underwent VATS and sublobectomy surgery (Table 3). We also compared the second primary lung adenocarcinoma and second primary lung cancers with different pathological types, and the results showed that there were more patients with a smoking history in the second primary lung non-adenocarcinoma group, and BMI was lower in the former group than in the latter group (Supplementary Table 1).

Table 3 Comparison of simultaneous and metachronous multiple primary lung cancersPrognosis and prognostic factors of different disease categories of MPLC

The 1-, 3-, and 5-year OS rates of 202 MPLC patients were 97.98%, 90.18%, and 82.81%, respectively. Patients with GG/L nodules had significantly better survival than was found in SPLC patients (1-, 3-, and 5-year OS, P < 0.05) (Fig. 2-B).

Prognosis and prognostic factors of GG/L lung cancer and SPLC

The 1-, 3-, and 5-year OS rates of 139 GG/L lung cancer patients were 99.27%, 94.76%, and 87.94%, respectively. Univariate analysis suggested that the presence of symptoms, the tumor location relationship (bilateral or ipsilateral), and the highest tumor stage were prognostic factors. Multivariate analysis suggested that the highest tumor stage was an independent prognostic factor. OS was significantly better in stage I patients (n = 116) than in stage II-III patients (n = 23) (5-year survival, 90.2% vs. 75.8%, P = 0.051). (Supplementary Table 2, Fig. 2-C). The 1-, 3-, and 5-year survival rates of 63 SPLC patients were 95.11%, 78.20%, and 71.29%, respectively. Univariate analysis suggested that the type of MPLC (sMPLC or mMPLC) and the highest tumor stage were prognostic factors, while multivariate analysis demonstrated that the highest tumor stage was an independent prognostic factor. The prognosis was better in stage I patients (n = 35) than in stage II-III patients (n = 28) (5-year survival, 78.5% vs. 58.0%, P = 0.008) (Supplementary Table 3, Fig. 2-D).

Prognosis and prognostic factors of sMPLC and mMPLC

The 1-, 3-, and 5-year OS rates of 171 sMPLC patients were 97.60%, 88.34%, and 80.88%, respectively. Univariate analysis suggested that sex, smoking history, family history of cancer, symptoms, category of MPLC (GG/L nodules or SPLC), and the highest tumor stage were prognostic factors for OS (P < 0.05). Multivariate analysis demonstrated that sex (P = 0.003) and the highest tumor stage (P < 0.001) were independent prognostic factors for OS. The prognosis was significantly better in female patients (n = 102) than in male patients (n = 69) (5-year survival, 88.0% vs. 69.5%, P = 0.003). The prognosis was significantly better in stage 1 (n = 127) (the highest tumor stage) patients than in stage II-III patients (n = 44) (5-year survival, 86.9% vs. 66.2%, P < 0.001) (Table 4 and Supplementary Fig. 1). The 1-, 3-, and 5-year OS rates of 31 mMPLC patients were 100%, 100%, and 93.10%, respectively. Univariate analysis identified no significant prognostic factors for mMPLC patients. Although the difference in prognosis between stage I (n = 24) patients and stage II-III (n = 7) patients was not significant, the prognosis was better in stage I patients than in stage II-III patients (5-year survival, 89.2% vs. 32.1%, P = 0.051) (Supplementary Table 4).

Table 4 Prognostic factors of simultaneous multiple primary lung cancers