Overall incidence of a new cancer diagnosis was low after hip replacement.
Patients who receive metal-on-metal hip replacements do not appear to have an increased risk of cancer during the first several years after the operation, a British group reported.
Alison J. Smith, MSc, a statistician at the University of Bristol, United Kingdom, and colleagues examined the incidence of new cancers in 40,576 patients who underwent hip replacement surgery with metal-on-metal bearing surfaces and 248,995 patients whose surgery involved other bearing surfaces.
They found no link between metal-on-metal hip replacements and an increased incidence of a cancer diagnosis during the first seven years after surgery.
“These data are reassuring, but the findings are observational with short follow-up,” the authors cautioned.
Metal-on-metal total hip replacements are currently responsible for 35% of hip replacements in the United States and 14% of hip replacements in England and Wales, the authors said. After the procedure, metal particles are disseminated throughout the body and can be found in many organs including marrow, blood, liver, kidneys, and bladder. Although these particles can cause DNA damage, it is unclear whether metal-on-metal hip replacements are associated with an increase in cancer.
The investigators obtained patient data from the National Joint Registry of England and Wales, which compiles information about primary and revision joint replacement procedures, and the National Health Service. They used data from hospital episode statistics for all hospital admissions for patients between 1997 and 2010 in order to identify cancer incidence.
These data are reassuring, but the findings are observational with short follow-up. ”
—Allison J. Smith MSc
Results showed that the overall incidence of a new cancer diagnosis was low after hip replacement and lower than that predicted for the age- and sex-matched general population (1.25% at 1 year; 95% CI, 1.21%-1.30% vs 1.65%; CI, 1.60%-1.70%).
The authors cited as a study strength the inclusion of a large representative sample of patients with hip replacement, which allowed for “some confidence in the findings for the period studied.” They emphasize, however, that they cannot reliably extrapolate their findings to the long term, given that some cancers may have a lengthy latency period, and thus will require much longer follow-up.
Smith AJ, Dieppe P, Porter M, Blom AW, on behalf of the National Joint Registry of England and Wales. Risk of cancer in first seven years after metal-on-metal hip replacement compared with other bearings and general population: linkage study between the National Joint Registry of England and Wales and hospital episode statistics. BMJ. 2012;344:e2383.