Are We Playing It Safe?

Conclusion

The data from three large biologics registers give reassuring messages regarding the overall risk of incident cancers in patients treated with TNF blocking agents. Concerning the clinically important question of whether we can treat patients with prior malignancies with these agents, an explanation for the discrepant results between the British and the German registers could be that in the German register, the time between onset of the first tumor and start of treatment with a TNF inhibitor was considerably shorter than in the BSRBR (mean, 7.4 years compared with 11.5 years). Further, there was a difference between the registers in the comparator groups—a mean of 7.4 years since the last tumor at start of a conventional DMARD in the German register and 8.5 years in the British register. This means that more patients in both groups in the German register and more patients in the control cohort in the British register were treated within a time window where we have to expect an increased risk of recurrence. This suggestion is supported by the fact that in the German register, the recurrent malignancies in the TNF groups were all true recurrences of the same tumor type and site, whereas in the British register, new tumor types mainly occurred, and those types were unrelated to the first tumor. With their strategy of waiting longer before starting treatment with TNF inhibitors, the British colleagues were more on the safe side, which may explain their even lower risk in the TNF inhibitor group. However, patients with very active disease may be willing to accept a potentially and insignificantly increased risk of recurrence for the sake of adequate treatment of their RA. Therefore, the final responsibility remains with the treating physician. Data from other countries, possibly reflecting different practice styles, may be able to elucidate this further in the near future.

Dr. Strangfeld is group leader of the pharmacoepidemiology group and Dr. Zink is head of the epidemiology department at the German Rheumatism Research Center in Berlin.

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