Cancer incidence and cause-specific mortality in patients with metal-on-metal hip replacements in Finland

Figures & data

Table 1. Number of patients (n) according to age at operation, and number of person-years according to the age at follow-up. The non-metal-on-metal cohort consisted of implants with metal-on-polyethylene, ceramic-on-polyethylene, and ceramic-on-ceramic bearing surfaces

	Metal-on-metal (MoM) cohort				Non-metal-on-metal cohort
	Men		Women		Men		Women
Age	n	Person-years	n	Person-years	n	Person-years	n	Person-years
< 20	6	14	3	16	–	–	–	–
20–29	25	101	16	56	4	17	7	23
30–39	158	435	67	236	30	101	20	87
40–49	741	2,833	468	1,569	143	616	157	491
50–59	2,275	8,516	1,642	6,226	850	3,327	922	3,711
60–69	2,257	11,955	1,581	8,383	2,260	11,140	2,739	12,557
70–79	762	4,599	594	3,263	3,044	19,193	5,394	29,603
≥ 80	65	430	48	346	697	7,844	1,953	20,193
Total	6,289	28,884	4,419	20,094	7,028	42,239	11,192	66,665

Table 2. Observed numbers of cancer cases, the expected numbers of cancer cases approximated from the Finnish population, and standardized incidence ratios with 95% confidence intervals—according to site—are given for the metal-on-metal cohort and for the non-metal-on-metal cohort. The latter cohort consisted of implants with metal-on-polyethylene, ceramic-on-polyethylene, and ceramic-on-ceramic bearing surfaces

	MoM cohort				Non-MoM cohort
Primary site	Obs	Exp	SMR	95% CI	Obs	Exp	SMR	95% CI
All sites	497	534	0.93	0.85–1.01	1952	1908	1.02	0.98–1.06
Stomach	13	12	1.08	0.57–1.84	57	53	1.07	0.81–1.39
Colon	20	29	0.69	0.42–1.05	118	132	0.89	0.74–1.06
Lung	32	53	0.61	0.41–0.85 ^b	126	181	0.70	0.58–0.82 ^c
Corpus uteri	14	13	1.08	0.59–1.81	61	58	1.05	0.80–1.35
Prostate	135	124	1.09	0.91–1.27	334	334	1.00	0.90–1.10
Kidney	16	18	0.91	0.52–1.47	62	61	1.01	0.77–1.29
Bladder	11	18	0.61	0.30–1.08	80	71	1.12	0.89–1.39
Soft-tissue sarcoma	7	3	2.14	0.86–4.40	11	12	0.95	0.47–1.69
Non-Hodgkin lymphoma	17	21	0.82	0.48–1.31	81	73	1.11	0.88–1.38
Hodgkin lymphoma	1	1	0.79	0.02–4.40	1	3	0.35	0.01–1.92
Multiple myeloma	5	6	0.79	0.26–1.83	28	28	1.02	0.68–1.47
Leukemia	7	9	0.75	0.30–1.55	38	38	1.00	0.71–1.37
Melanoma	21	19	1.09	0.67–1.65	73	56	1.30	1.02–1.63 ^a
Basalioma	178	132	1.35	1.16–1.55 ^c	626	586	1.07	0.99–1.15

Obs: observed number of cancer cases; Exp: expected number of cancer cases from the Finnish population;

SIR: standardized incidence ratio; CI: confidence interval.

^a p < 0.05, ^b p < 0.01, ^c p < 0.001.

Table 3. SIR/SIR ratios for the metal-on-metal group and the non-metal-on-metal group (consisting of implants with metal-on-polyethylene, ceramic-on-polyethylene, and ceramic-on-ceramic bearing surfaces) with 95% confidence intervals, according to site

Primary site	SIR/SIR ratio	95% CI
All sites	0.91	0.82–1.00
Stomach	1.01	0.56–1.82
Colon	0.77	0.48–1.23
Lung	0.87	0.59–1.28
Prostate	1.09	0.89–1.33
Kidney	0.87	0.51–1.51
Bladder	0.54	0.29–1.01
Uterus	1.02	0.58–1.82
Soft tissue	2.55	1.02–6.36
Non-Hodgkin lymphoma	0.73	0.44–1.22
Hodgkin lymphoma	3.00	0.31–28.7
Multiple myeloma	0.83	0.33–2.09
Leukemia	0.78	0.35–1.71
Melanoma	0.85	0.52–1.37
Skin, basal cell carcinoma	1.26	1.07–1.49

SIR: Standardized incidence ratio.

Table 4. Observed and expected numbers of deaths, and standardized mortality ratios for the metal-on-metal and non-metal-on-metal cohorts in the main disease groups

	MoM cohort				Non-MoM cohort
Cause of death	Obs	Exp	SMR	95% CI	Obs	Exp	SMR	95% CI
Cancer	114	173	0.66	0.55–0.78 ^c	764	873	0.87	0.81–0.93 ^c
Cardiovascular	131	196	0.67	0.56–0.78 ^c	1,274	1,719	0.74	0.70–0.78 ^c
Respiratory	11	25	0.44	0.22–0.78 ^b	84	204	0.41	0.33–0.50 ^c
Accidents and violence	45	46	0.97	0.71–1.29	180	158	0.82	0.69–0.97 ^a
All causes	365	562	0.65	0.58–0.71 ^c	2,785	3,846	0.72	0.70–0.75 ^c

MoM: metal-on-metal; Obs: observed number of deaths; Exp: expected number of deaths; SMR: standardized mortality ratio; CI: confidence interval.

^a p < 0.05, ^b p < 0.01, ^c p < 0.001.

Standardized mortality ratios (SMRs) for deaths from all diseases in annual follow-up of metal-on-metal (MoM) and non-metal-on-metal (non-MoM) cohorts.