Phase 2 Randomized Controlled Trial of Radiation Therapy Plus Concurrent Interferon-Alpha and Retinoic Acid Versus...

Because a combination of retinoic acid, interferon-alpha, and radiation therapy demonstrated synergistic action and effectiveness to treat advanced cervical cancers in earlier studies, we designed this randomized phase 2 open-label trial to assess efficacy and safety of interferon alpha-2b (IFN) and 13-cis-retinoic acid (RA) administered concomitantly with radiation therapy (IFN-RA-radiation) to treat stage III cervical cancer.

Stage III cervical cancer patients were randomized to study and control groups in a 1:1 ratio. All patients were treated with radiation therapy; study arm patients received IFN (3 × 10(6) IU subcutaneously) 3 times a week for 4 weeks and daily RA (40 mg orally) for 30 days starting on day 1 of radiation, whereas control arm patients received weekly cisplatinum (40 mg/m(2)) for 5 weeks during radiation. Patients were followed for 3 years. The primary endpoint was overall survival at 3 years.

Patients in the study (n=104) and control (n=105) groups were comparable for clinicopathological characteristics, radiation therapy-related variables and treatment response. Proportions of disease-free patients in the study and control groups were 38.5% and 44.8%, respectively, after median follow-up of 29.2 months. Hazard ratios were 0.67 (95% confidence interval [CI]: 0.44-1.01) and 0.69 (95% CI: 0.44-1.06) for overall and disease-fee survival, respectively, comparing the study group to control, and demonstrated an inferior outcome with RA-IFN-radiation, although differences were statistically nonsignificant. Kaplan-Meier curves of disease-free and overall survival probabilities also showed inferior survival in the study group compared to those in the control. Acute toxicities of chemoradiation were significantly higher with 2 acute toxicity-related deaths.

Treatment with RA-IFN-radiation did not demonstrate survival advantage over chemoradiation despite being less toxic. The trends predicted an inferior outcome with the RA-IFN combination.