The incidence and risk of developing a second primary esophageal cancer in patients with oral and pharyngeal carcinoma: a population-based study in Taiwan over a 25 year period

Table 5 Risk for second esophageal cancer by calendar period at diagnosis of oral/pharyngeal cancer.

First primary cancer site (ICD-9)	Calendar year	OPY	O	E	SIR (O/E)	(95% CI)
Oral cavity (140-1, 143-145)	1979-1993	20031	27	8.94	8.94	(5.89-13.01)
	1994-2003	70613	72	4.89	4.89	(3.83-6.16)
Oropharynx (146, 149)	1979-1993	2930	2	4.55	4.55	(0.51-16.41)
	1994-2003	8373	28	16.87	16.87	(11.21-24.38)
Hypopharynx (148)	1979-1993	3052	18	25.35	25.35	(15.02-40.07)
	1994-2003	8160	53	21.99	21.99	(16.47-28.77)

Bold indicates statistical significance.
OPY = observed person years; SIR = standardized incidence ratio; O = observed numbers of second esophageal cancer; E = expected numbers of second esophageal cancer; CI = confidence interval.

ISSN: 1471-2407