No generally increased risk of cancer after total hip arthroplasty performed due to osteoarthritis

Abstract

Previous studies on the risk of cancer after total hip arthroplasty (THA) contradict each other, and many are hampered by small cohort sizes, residual confounding, short observation times or a mix of indications underlying the THA procedure. We evaluated the risk of cancer after total hip arthroplasty due to osteoarthritis in a nationwide cohort by comparing cancer incidences in individuals exposed to total hip arthroplasty due to osteoarthritis and in unexposed, sex-, age-and residence matched individuals. To address some previous studies' shortcomings, information on comorbidity and socioeconomic background were obtained and adjusted for. We included 126,276 patients exposed to a cemented THA between 1992 and 2012, and 555,757 unexposed individuals. Follow-up started on the day of surgery for exposed individuals and respective date for matched, unexposed individuals, and ended on the day of death, emigration, censuring or December 31st, 2012, whichever came first. The Swedish Hip Arthroplasty Registry (SHAR), the Swedish Cancer Registry, the Swedish National Patient Registry and Statistics Sweden were accessed to obtain information on procedural details of the THA, cancer diagnoses, comorbidities, and socioeconomic background. The primary outcome measure was the occurrence of any cancer after the index date. Exposed individuals had a slightly lower adjusted risk of developing any cancer than unexposed individuals (hazard ratio [HR] 0.97; CI 0.95-0.99). The only cancer with a statistically significant risk increase in exposed individuals was skin melanoma (HR 1.15; CI 1.05-1.24). We attained similar risk estimates in analyses stratified by sex, in individuals with minimum 5 years of follow-up, in an analysis including individuals with a history of previous cancer, and in patients with cementless THA. In this study on a large and well-defined population with long follow-up, we found no increased overall risk of cancer after THA. These reassuring findings could be included in the guidelines on preoperative information given to THA patients.Additional Supporting Information may be found in the online version of this article.

Similar risk of cancer in patients younger than 55 years with or without a total hip arthroplasty (THA): a population- based cohort study on 18,771 exposed to THA and 87,683 controls

“…We find an about equal risk of cancer in younger patients exposed to THA when related to a sample from a comparable population, which is in agreement with previous studies on older populations (17,18,40). The increased melanoma risk in exposed males confirms data from a meta-analysis in which a 1.4-fold risk of developing melanoma was described for arthroplasty patients, though of higher mean age (14,16).…”

“…The hitherto largest observational study on cancer after THA includes 403,881 individuals, but the median age in the 3 subgroups of patients investigated in that study, divided by different types of THA, ranges from 55 to 70 years (40). The second largest cohort of 126,276 THA includes osteoarthritis patients with a mean age of 71 years (17), and the mean age in other studies on populations of similar sizes as that presented in our study is centered on 68-70 years (12,18,(41)(42)(43). Although even longer observation times would be desirable when investigating cancer risks in young individuals, a strength of our study is its median observation time of around 8 years, which is longer than in most other studies on the topic of cancer after THA.…”

“…Although even longer observation times would be desirable when investigating cancer risks in young individuals, a strength of our study is its median observation time of around 8 years, which is longer than in most other studies on the topic of cancer after THA. Only 2 other studies report similar observation times (12,43), and only 1 has a longer observation time of 14 years (17).…”

“…Our study design with individuals exposed to a THA at the beginning of the study compared with unexposed individuals who may be exposed to a THA at a later time point resembles a prospective cohort study. All other studies on cancer after THA, except our previous study (17), either have no comparison group, or compare with individuals among whom no one was ever exposed to a THA, a scenario that is highly improbable in real life. Some previous studies compare cancer incidences in cohorts exposed to THA populations with a standardized incidence ratio (12,16,41) a measure that has its strengths while on the other hand opening up for selection bias, as patients scheduled for THA deviate from the general population in terms of comorbidity, mortality, and socioeconomic factors (29,44).…”

“…Observational studies show small increases in the risk of developing hematological or lymphatic malignancies (1,11,12) and an enhanced incidence of solid tumors in the prostate or skin after THA or knee arthroplasty (13)(14)(15)(16)(17), but these findings are contradicted by others (14,(17)(18)(19). Most of the cited studies base their findings on "average" THA populations with a mean age between 60 and 70 years at the time of surgery, but none specifically addresses the cancer risk in younger THA patients who are exposed to their implants and potentially toxic derivatives for much longer periods of time than elderly patients.…”