Table 2. Metastases in groups of mediastinal lymph nodes according to Naruke map.

N2 feature	n	Average survival (months), N2/N0	P
Right lung (n=44)
Group No. 2	4	x	x
Group No. 3	1	x	x
Group No. 4	28	17/48	0.0148
Group No. 7	47	29/36	0.4480
Group No. 8	5	x	x
Group No. 9	6	x	x
Left lung (n=66)
Group No. 4	15	17/ 36	0.2946
Group No. 5	37	24/ 36	0.7268
Group No. 6	20	13/34	0.3269
Group No. 7	37	12/57	0.0008
Group No. 8	1	x	x
Group No. 9	9	x	x

x, small numbers—making a statistical analysis is not possible.