Table 2. Characteristics of patients with histologically confirmed respiratory tract carcinomas, Singapore Chinese Health Study 1993-2005.

	Upper respiratory tract		Lower respiratory tract
	Nasopharyngeal carcinoma	Non-nasopharyngeal carcinoma	Lung carcinoma
Number of cases	175	150	821
Proportion of males	68.6%	83.3%	70.0%
Mean age at diagnosis (years)	59.1	66.7	68.2
Histological subtype
Squamous cell carcinoma	5 (2.9%)	132 (88.0%)	195 (23.8%)
Undifferentiated carcinoma	155 (88.6%)	4 (2.7%)	14 (1.7%)
Adenocarcinoma	2 (1.1%)	5 (3.3%)	342 (41.7%)
Small cell carcinoma	0	0 (0.7%)	97 (11.8%)
Other or unspecified carcinoma	13 (7.4%)	9 (6.0%)	173 (21.1%)