Table 1.

Characteristics of the studied subjects from the Cytology Sampling Study 2 cancer screening study

	N(total=333)	percentage
Tobacco smoker?
Yes	42	12.6%
No	291	87.4%
Gender
Female	162	48.6%
Male	171	51.4%
Balloon sampling device
Chinese Balloon	161	48.3%
Wilson-Cook Balloon	172	51.7%
Antibiotic usage within the last 3 months?
Yes	42	12.6%
No	291	87.4%
Histologically diagnosed esophageal squamous dysplasia?
Yes	142	42.6%
No	191	57.4%

	Mean	sda
Age	55.03	4.54
Pepsinogen I/II ratio	9.40	4.12
No. of genera	22.93	6.11
No. of families	16.93	3.26
No. of orders	12.12	1.84
No. of classes	10.02	1.19
No. of phyla	5.37	0.72

^astandard deviation