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 4 Risk for second esophageal cancer by age at initial onset among 33,782 patients with oral/pharyngeal cancer.

First primary cancer site (ICD-9)	Age (yrs)	OPY	O	E	SIR (O/E)	95% CI
Oral cavity (140-1, 143-145)	≤50	39031	39	3.54	11.01	(7.83-15.05)
	50-60	24591	30	5.65	5.31	(3.58-7.58)
	> 60	27022	30	8.54	3.51	(2.37-5.02)
Oropharynx (146, 149)	≤50	4333	14	0.30	46.49	(25.40-78.01)
	50-60	2869	11	0.62	17.73	(8.84-31.73)
	> 60	4101	5	1.18	4.22	(1.36-9.85)
Hypopharynx (148)	≤50	2479	20	0.28	71.53	(43.67-110.48)
	50-60	3300	26	0.83	31.22	(20.39-45.75)
	> 60	5433	25	2.01	12.47	(8.07-18.41)

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; yrs = years.

ISSN: 1471-2407