983 - The Use of Biologic Therapy in Patients with RA and Existing Cancer

Frederick Wolfe, Kaleb Michaud. National Data Bank for Rheumatic Diseases, Wichita, KS
Presentation Number: 983

PURPOSE. Although biologic therapy is widely used in the treatment of RA, concern remains, on theoretical grounds, that biologic therapy might increase the risk of cancer development or speed up growth of existing cancers. In addition to medical concerns, biologic prescription has potential legal implications if the prescription of biologics leads to increased cancer rates. In this report we examine prevalence of existing (non-incident) cases of cancer in RA, determine the extent to which biologic therapy is being used in persons with pre-existing malignancy compared with those without cancer, and determine the factors that lead to prescription of biologic in persons with pre-existing cancer.
METHODS. After excluding 1860 incident cases of cancer, we studied existing (non-incident) cases of cancer among the remaining 18,152 subjects during 60,958 patient years of observation in the years 1998-2005. Cancer reports were validated by hospital, physician and death records. The risk of prescription of biologics among patients with pre-existing cancer was studied with conditional logistic regression to calculate odds ratios as estimates of the relative risk (RR) of the various cancers, conditioning on semiannual entry and exit period. Analyses were adjusted for the probability of prescription of biologics.
RESULTS. Pre-existing non-melanotic cancers were noted in 10.6% (1,931) at study entry. The prevalence of the most common malignancies is shown in Table 1. Breast and prostate cancer dominated the prevalent cancers, 28.2 per thousand women and 29.5 per thousand men, followed by colon cancer and melanoma. In 11,705 patients studied in 2004 and 2005, the RR (95% CI) of being treated with a biologic for patients with existing cancers compared to patients without cancer was 0.79 (0.73-.85) overall. For specific cancers the RR was: breast 0.70 (0.61-0.81), colon 0.60 (0.42-0.85), lymphoma 1.00 (0.67-1.58) and prostate 0.78 (0.59-1.00). Among patients with pre-existing cancer, multivariable analyses demonstrated that biologic prescription was reduced in patients <65 years of age (RR 0.55 (0.47-0.64), increased in non-Hispanic Whites (RR 4.2 (3.27-5.48) and in those with higher HAQ scores (RR 1.81 (1.67-1.98). There was no association with medical insurance, education or sex.
CONCLUSIONS. For the 10% of patients with existing cancer, the probability of being treated with a biologic is reduced by 29%. This can be interpreted to indicate that there is only a slight reluctance to prescribe biologics and that the standard of practice is not substantially to restrict biologics. In addition to physician beliefs of about biologic safety, demographic features and disease severity also influence biologic prescription among patients with cancer.
Prevalent Cancers per 1,000 RA Patients (Excluding Incident Cases)
Prevalent Cancers per 1,000 RA Patients (Excluding Incident Cases)
All Cancers106410691049

  F. Wolfe, The NDB has received research support from Abbott, Amgen, Bristol-Myers-Squibb and Centocor, 2; K. Michaud, None.