Table 3 Results of sensitivity to zeros analyses

Disease	Excluding studies with no cases		Adding 1 to observed and expected		Setting observed = expected		Number of studies with no cases
Disease	SMR (n)	95% CI	SMR (n)	95%CI	SMR (n)	95% CI	Number of studies with no cases
Cancer of the buccal cavity and pharynx	2.34 (12)	1.45 to 3.77	1.42 (28)	1.01 to 2.00	2.06 (28)	1.49 to 2.93	16
Cancer of the oesophagus	2.25 (14)	1.55 to 3.29	1.64 (26)	1.20 to 2.24	2.07 (26)	1.45 to 2.96	12
Cancer of the stomach	1.35 (20)	1.06 to 1.72	1.20 (32)	0.98 to 1.48	1.30 (32)	1.04 to 1.79	12
Cancer of the rectum	1.57 (17)	1.19 to 2.07	1.37 (28)	1.07 to 1.76	1.52 (28)	1.16 to 1.97	11
Cancer of the larynx	3.49 (8)	1.98 to 6.14	1.58 (23)	1.09 to 2.31	2.69 (23)	1.63 to 4.46	15
Cancer of the lung	1.23 (30)	1.06 to 1.43	1.22 (32)	1.05 to 1.41	1.23 (32)	1.06 to 1.42	2
All lymphatic and haemapoietic cancer	1.41 (25)	1.17 to 1.69	1.34 (33)	1.12 to 1.60	1.39 (33)	1.16 to 1.66	8
Lymphoma	2.79 (14)	1.97 to 3.97	1.98 (26)	1.45 to 2.69	2.57 (26)	1.88 to 3.52	12