Prolonged use of human insulin increases breast cancer risk in Taiwanese women with type 2 diabetes

Tseng, Chin-Hsiao

doi:10.1186/s12885-015-1876-7

BMC Cancer

Table 2 Exposure to human insulin and incidences of breast cancer and the adjusted hazard ratios comparing exposed to unexposed

From: Prolonged use of human insulin increases breast cancer risk in Taiwanese women with type 2 diabetes

Exposure to human insulin	Case number	Incident breast cancer	%	Person-years	Incidence rate (per 100,000 person-years)	Primary model			Sensitivity model I			Sensitivity model II
Exposure to human insulin	Case number	Incident breast cancer	%	Person-years	Incidence rate (per 100,000 person-years)	HR	95 % CI	P	HR	95 % CI	P	HR	95 % CI	P
Never-users	422235	4711	1.12	2190014.8	215.1	1.000			1.000			1.000
Ever-users	59798	559	0.93	268941.3	207.9	1.033	(0.936-1.139)	0.5200	0.994	(0.907-1.090)	0.9013	1.033	(0.936-1.139)	0.5200
Time since starting human insulin (months)
Never-users	422235	4711	1.12	2190014.8	215.1	1.000			1.000			1.000
<35	19409	165	0.85	88579.0	186.3	0.924	(0.787-1.085)	0.3358	0.877	(0.750-1.027)	0.1024	0.924	(0.787-1.085)	0.3358
35-67	19817	173	0.87	89856.1	192.5	0.988	(0.843-1.158)	0.8813	0.944	(0.809-1.101)	0.4603	0.988	(0.843-1.158)	0.8813
≥67	20572	221	1.07	90506.3	244.2	1.185	(1.026-1.368)	0.0209	1.161	(1.011-1.333)	0.0342	1.185	(1.026-1.368)	0.0209
Cumulative dose of human insulin exposure (units)
Never-users	422235	4711	1.12	2190014.8	215.1	1.000			1.000			1.000
<4,000	19106	151	0.79	89076.3	169.5	0.872	(0.738-1.030)	0.1069	0.819	(0.695-0.965)	0.0169	0.982	(0.837-1.152)	0.8264
4,000-39,000	20322	170	0.84	89166.3	190.7	0.960	(0.818-1.126)	0.6148	0.919	(0.787-1.073)	0.2863	1.184	(1.017-1.380)	0.0298
≥39,000	20370	238	1.17	90698.7	262.4	1.260	(1.096-1.450)	0.0012	1.239	(1.084-1.416)	0.0017	0.961	(0.828-1.115)	0.5987
Cumulative duration of human insulin exposure (months)
Never-users	422235	4711	1.12	2190014.8	215.1	1.000			1.000			1.000
<2.8	19751	151	0.76	90689.0	166.5	0.855	(0.724-1.009)	0.0643	0.809	(0.687-0.953)	0.0112	0.855	(0.724-1.009)	0.0643
2.8-21.7	19716	167	0.85	87633.9	190.67	0.981	(0.834-1.153)	0.8142	0.927	(0.792-1.084)	0.3407	0.981	(0.834-1.153)	0.8142
≥21.8	20331	241	1.19	90618.4	266.0	1.257	(1.094-1.446)	0.0013	1.240	(1.085-1.416)	0.0015	1.257	(1.094-1.446)	0.0013

HR: hazard ratio, CI: confidence interval
Primary model: adjusted for all variables listed in Table 1.
Sensitivity model I: adjusting only for important risk factors of breast cancer including age, diabetes duration, obesity, estrogen, metformin, statin and angiotensin converting enzyme inhibitor/angiotensin receptor blocker.
Sensitivity model II: including human insulin exposure post entry date but prior to breast cancer diagnosis in the calculation of the dose–response parameters.

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