Background: Concurrent chemo-radiation (CT-RT) is a standard therapy for squamous cell carcinoma of anal canal. Different clinical and biological factors may potentially affect outcome. We investigated the prognostic role of baseline hemoglobin (Hb) in a cohort of anal cancer patients submitted to CT-RT with 5-fluorouracil and mitomycin C.
Methods: Up to 161 patients with clinical stage T1-T4/N0-N3/M0 were treated. Response was assessed at 6 weeks and thereafter at 3, 6 and 12 months. Two different approaches were used:a)simultaneous integrated boost following RTOG 05-29 indications;b)first sequence of 45Gy/25 fractions to the pelvis followed by 9-14.4 Gy/5-8 fractions to the macroscopic disease. Primary endpoints were progression-free survival (PFS) and overall survival (OS).
Results: On multivariate analysis, pre-treatment Hb level had a significant correlation to OS (HR:0.53;95% CI:0.33-0.87; p = 0.001), but not to PFS (HR:0.78;95% CI:0.53-1.15; p = 0.12) Patients with pre-treatment Hb ≥ 12 g/dl had 5-year PFS and OS of 82.2%, compared to 29.3% and 32.8% for those below the threshold. The likelihood to achieve a complete remission increased by 5.6% for every single-unit (g/dl) increase in baseline Hb level over 11 g/dl. On multivariate analysis, response to treatment had a significant correlation to PFS (incomplete vs complete response - HR:5.43;95% CI:2.75-10.7; p < 0.0001) and OS (HR: 6.96;95% CI:2.96-16.5; p < 0.0001).
Conclusions: We showed that baseline Hb level is a strong indicator for poor response to RT-CT in anal cancer patients. A close clinical monitoring for incomplete response to treatment should be advised in patients with low pre-treatment Hb. The hypothesis that the preservation of adequate Hb level during treatment may lead to a better outcome needs prospective evaluation.
Keywords: Anal cancer; Anemia; Hematologic toxicity; Hemoglobin; Prognostic factors.