(HealthDay News) – Hip replacements with metal-on-metal bearing surfaces do not seem to be associated with cancer incidence.

To investigate whether metal-on-metal bearing surfaces are associated with an increased risk of cancer diagnosis, Alison J. Smith, from the University of Bristol in the United Kingdom, and colleagues examined the incidence of new diagnoses of cancer in 40,576 patients with hip replacements with metal-on-metal bearing surfaces and 248,995 with alternative bearings. The incidence of all cancers, and of malignant melanoma and hematological, prostate, and renal cancers was assessed.

The researchers found that the incidence of new cancer diagnoses after hip replacement was lower than that predicted from the age-matched and sex-matched general population and was 1.25% at one year. In the seven years following surgery, there was no evidence that metal-on-metal bearing surfaces correlated with an increased risk of cancer diagnosis compared with alternative bearings. There was also no increase seen in the risk of malignant melanoma or hematological, prostate, or renal tract cancers. For all cancers, the adjusted five-year incidence for men and women, respectively, was 4.8 and 3.1% with resurfacing; 6.2 and 4% with stemmed metal-on-metal; and 6.7 and 4.4% with other bearings.

“These data are reassuring, but the findings are observational with short follow-up,” the authors write. “Furthermore, as some cancers have a long latency period it is important that we study the longer term outcomes and continue to investigate the effects of exposure to orthopedic metals.”

One of the authors disclosed financial ties to DePuy.

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