Abstract
Aims: In 1999 we published a cohort of 24,638 polyethylene-on-metal total hip arthroplasty (THA) patients followed up for cancer, using Finnish Cancer Registry data, from 1980 to 1995. The number of person-years was then 173,022 (until 31st Dec, 1996). During follow-up, there were statistically significantly fewer cancers among the THA patients (standardized incidence ratio [SIR], 0.91; 95% confidence interval [Cl], 0.87–0.94). There was no significantly increased risk at any site, and for certain cancers that was even below the unity (lung and stomach).
On the longer run, however, certain tendency for increased risk for cancer of the urinary bladder, myeloma, and leukemia could be observed; SIRs were greater than unity with the THA patients followed up 3 to 9 years. Further follow-up of the cohort is therefore needed. Methods: The follow-up of the same cohort, originally identified in the National Register of Arthroplasties, maintained by the National Agency for Medicines (primary THA with primary arthritis as the indication) was expanded with a four year period (from 1st of Jan 1997 to 31st of Dec 2000). Follow-up for cancer was undertaken using the files in the population-based, nationwide Finnish Cancer Registry, employing personal identification numbers.
Follow-up for cancer started at the date of first hip replacement and ended on emigration, death, or December 31, 2001, whichever occurred first. Multiple cancers were taken account of in similar ways in relation to observed and expected numbers of cases. Results: After excluding revision and infective or systemic disease as indications for operation, there were 9,479 men and 15,157 women in the cohort followed. The updated numbers for person-years were 89,295 for males and 153,759 for females. The mean duration of follow-up was now 9,9 years. The total risk for cancer was now 0.93 (95%Cl 0.90–0.96) and that for stomach 0.89, for colon 0.90, lung 0.64, for urinary organs 1.01, and for connective tissues 0.88. The SIRs for non-Hogkin lymphoma, myeloma and leucemia were all under the untity, 0.88, 1.09 and 0.73, respectively, without any tendency for increased risk in the follow-up of plus ten years.
Conclusions: These findings indicate that the risk of hematopoietic cancers is not increased after THA using polyethylene-on-metal prostheses. Expanding of the follow-up with four years did not markedly change the profile of the SIRs at any specific site, and contrary to our earlier report there were increased risk left of myeloma and leucemia with increased follow-up time. The SIRs associated with soft tissue cancers and bone sarcomas were not significantly different from unity. No sarcomas developed at the site of a prosthesis.
Theses abstracts were prepared by Professor Dr. Frantz Langlais. Correspondence should be addressed to him at EFORT Central Office, Freihofstrasse 22, CH-8700 Küsnacht, Switzerland.
Reference:
Paavolainen P, Pukkala E, Pulkkinen P, Visuri T.: Cancer incidence in Finnish hip replacement patients from 1980 to 1995. A nation-wide cohort study involving 31,651 patients. J Arthroplasty14:272–279, 1999. Erratum: 15:136–137, 2000. Google Scholar
