LONDON – Biologic therapies do not increase the overall risk of cancer in patients with inflammatory arthritis, according to observational data from the Danish Biologics Register, DANBIO, presented by Dr. Lene Dreyer at the annual European Congress of Rheumatology.
After an average of 9 years of follow-up, and representing almost 24,000 patient-years of treatment, the relative risk (RR) for developing any type of cancer for the first time was 1.03 (95% confidence interval [CI] 0.82-1.30) when comparing anti–tumor necrosis factor (anti-TNF) therapy with no biologic treatment.
The cancer risk was also not increased in patients with rheumatoid arthritis (RR = 1.05; 95% CI 0.82-1.34), psoriatic arthritis (RR = 1.98; 95% CI 0.24-16.18), or other arthritic diseases including ankylosing spondylitis (RR = 0.79; 95% CI 0.08-8.33).
Preliminary results suggest that the risk of nonmelanoma skin cancer (RR = 1.11; 95% CI 0.70-1.76) and non-Hodgkin’s lymphoma are also not increased (RR = 0.55; 95% CI 0.16-1.90).
While the findings add to increasing evidence that biologics may not increase cancer risk overall, more analysis is needed to determine if certain types of cancer are more likely to occur in the study population, or if certain patients are at greater risk of malignancy than others. Longer follow-up is also needed to rule out cancers that may take longer than a decade to manifest.
"There has always been concern for an increased risk of lymphoma with TNF-blockers," said Dr. Georg Schett, chair of the department of internal medicine, rheumatology, and clinical immunology at Friedrich-Alexander University Erlangen in Nuremberg, Germany.
Dr. Schett, who was not involved in the study, added that patients with more active arthritis may be more likely than those with less active disease to receive anti-TNF treatment, and so these patients may already be at increased risk for lymphoma.
Indeed, recent data from the British Society for Rheumatology Biologics Register (BSRBR) have shown that the risk of cancer is almost doubled in patients with RA compared with the general population before they are even given biologics.
"There is an increased risk of cancer in patients with rheumatoid arthritis because of the disease itself," agreed study investigator Dr. Dreyer in an interview. In particular, there was an increased risk of lung cancer in Danish patients because of smoking, said Dr. Dreyer, who is a rheumatologist at Gentofte Hospital in Copenhagen.
Dr. Merete Lund Hetland, a consultant rheumatologist from Glostrup University Hospital in Copenhagen and chair of the Danish register, added in an interview: "I think as a [physician] you would always tell your patient, ‘Well, we don’t think there is an increased risk, but there’s always a risk, so you should tell us if you experience any signs or symptoms [that might indicate cancer].’ "
Putting the cancer risk in further context, Dr. Dreyer noted that the risk of infection was higher than that of malignancy, and that of course the benefits of biologic treatment would probably outweigh the risk of malignancy in the majority of patients.
DANBIO (Dansk Reumatologisk Database) was set up in 2000 to prospectively follow all patients starting treatment with anti-TNFs for their arthritis in Denmark. Enrollment in the register is mandatory and included more than 13,500 patients with all types of inflammatory arthritis up until the data cut for the analysis of 2008. Of the enrolled patients, 5,598 had received treatment with anti-TNF agents and 8,101 had not. Two-thirds of patients had rheumatoid arthritis.
To assess cancer risk, data from DANBIO were linked to the Danish Cancer Registry, with a total of 181 first cancers occurring in patients treated with biologics and 132 in those who were not given biologics.
The risk of cancer was the same for men and women, did not increase with the cumulative duration of active treatment, and was independent of the anti-TNF agent used (primarily infliximab, etanercept, and adalimumab).
Similar to other European biologics registers, DANBIO is funded by research grants from all the major players in the biologics market in Denmark. These grants run through the Danish Rheumatism Association and the Danish Cancer Society, and the sponsors have no direct access or influence on how the registry data are collected, analyzed, or published.
"All companies are involved. They all pay the same amount, and we would monitor all drugs regardless of whether there was a sponsor or not," Dr. Hetland said.
The DANBIO team plans to examine the association between biologic treatment and malignancy further, looking at the subtypes of cancer that develop. The team also plans to investigate in more detail the different types of cancer that develop by the type of arthritis.