[Clinico-pathologic and prognostic studies on lung adenocarcinoma patients under 40 years of age]

To study whether the clinico-pathologic characteristics and survival of young lung cancer patients < 40 years of age differ from those of lung cancer patients >or= 40 years of age.

Retrospective analysis was carried out to compare the clinico-pathologic features and survival of 129 young patients (young group) with those of 140 randomly selected older ones (elderly group).

The young group, when compared with the older group, had more female (P = 0.037), longer mean duration of symptoms (4.7 m vs 2.5 m, P < 0.001), higher misdiagnostic rate (65.1% vs 24.3%, P < 0.001) with longer mean duration of misdiagnosis for the misdiagnosed patients (5.6 m vs 2.5 m, P < 0.001), more adenocarcinoma (54.3% vs 42.1%, P < 0.001), higher pathologic grade (69.5% vs 36.0%, P < 0.001), more advanced-stage diseases at diagnosis (74.4% vs 45.7%, P < 0.001), more patients receiving combined-modality treatment (94.6% vs 62.1%, P < 0.001) and more distant failures as initial relapse (64.7% vs 50.6%, P = 0.02). The median survivals and 5-year survival rates were better in patients with stage I-II disease in the young group than the older group (54 m vs 33 m and 46.2% vs 25.0%, P = 0.0495), even though the overall median survivals and 5-year survival rates were similar in either group (11 m vs 14 m and 8.3% vs 11.9%, P = 0.2889). There was no difference in family or smoking history (P = 0.227 and 0.171).

Younger patients with lung cancer present difference in clinico-pathologic features from the older ones, but the survivals of the two groups are similar. To define younger lung cancer as "the younger type of lung cancer" may have a practical clinical significance.