No Cancer Risk With Biologic Use Save

Despite the evolving and cummulative evidence that biologic treatments do not affect a patient's cancer risk, concerns are still had by both patient and prescriber. 

A polulation-based study from Sweden has shown that treatment with tocilizumab, abatacept, rituximab, or tumor necrosis factor inhibitors (TNFi) does not affect the risk of malignant neoplasms among patients with rheumatoid arthritis. Specifically, use of a first or second TNFi or biologic DMARDs (bDMARD) does NOT confer a different cancer risk when compared to conventional DMARDS in biologic–naive RA patients.

Data were derived from a national register, prospective cohort study in Sweden from 2006 to 2015. Comparator groups included those initiating treatment with tocilizumab (n = 1798), abatacept (n = 2021), and rituximab (n = 3586), TNFi as first-ever (n = 10 782) or second-ever (n = 4347) bDMARD, and were compared to the general population cohort (n = 107 491) and a biologics-naive cohort treated with csDMARDs (n = 46 610). The primary outcome was a first invasive solid or hematologic malignant neoplasm, or skin cancer. 

Overall, the comparison groups included 15,129 initiations of TNFi as the first or second bDMARD, 7405 initiations of bDMARDs, and 46 610 csDMARD users.

Crude incidence rates for first invasive solid or hematologic malignant neoplasm were:

• TCZ - 959 (per 100 000 person-years) 
• ABA - 1026 (per 100 000 person-years)
• RTX - 1074 (per 100 000 person-years)
• 1st TNFi - 978 (per 100 000 person-years) ) as first bDMARD
• 2nd TNFi - 917 (per 100 000 person-years) as second bDMARD.
• csDMARD - 1328 (per 100 000 person-years) 
• General population - 953 (per 100 000 person-years) 

There were no statistically significant differences between initiators of a first or second TNFi, or other bDMARDs, and bDMARD-naive RA.

The adjusted point estimates for invasive solid or hematologic malignant neoplasms did NOT show any significant risk differences between biologics and conventional DMARDS:

• tocilizumab vs csDMARD: HR, 0.89 [95%, CI 0.67-1.18];
• abatacept vs csDMARD: HR, 0.88 [95% CI, 0.68-1.14];
• rituximab vs csDMARD: HR, 0.86 (95% CI, 0.73-1.03).
• 1st TNFi vs csDMARD:  HR 0.93 (95% CI, 0.85-1.01)
• 2nd TNFi vs cs DMARD: HR 0.89 (95% CI, 0.78-1.04)

Surprisingly, there were 17 events of squamous cell skin cancer in the abatacept cohort, with a resultant increased risk (HR, 2.15; 95% CI, 1.31-3.52) compared to vs csDMARD.

These population based data, with many years of followup after biologic exposure, fail to show any reasonable risk of cancer (solid or hematologic) that would be influenced by biologic use.