Serological immune responses to influenza vaccine in patients with colorectal cancer

The immune responses to influenza vaccination in patients with colorectal cancer on surveillance or active chemotherapy have not been previously reported. We conducted a prospective influenza vaccination study to determine the serological immune response rate in patients with colorectal cancer.

During the 2006-2007 influenza season, patients with colorectal cancer treated at Roswell Park Cancer Institute were offered vaccination with the trivalent influenza vaccine (Fluzone, 2006-2007). Blood samples for hemagglutination inhibition (HI) assay titers were collected before and 3 months after vaccination. Response to vaccination was determined using an endpoint of ≥ 1:40 HI titer ratio or a fourfold HI increase at 3 months from vaccination. A response in HI to at least one of the 3 strains was considered an immune response.

Eighty-five patients with colorectal cancer participated in the study. The immune response in the overall population was 70.6%. No differences in response were noted between the 58 patients on active chemotherapy and the 27 patients on surveillance [Odds Ratio (OR) = 0.78; P = 0.8]. The odds of response did not vary by chemotherapy regimen or by chemotherapy-vaccination timing. HI response in all 3 titers concurrently were low in both the chemotherapy (12.1%) and surveillance groups (11.1%) (OR = 1.10; P = 1).

Patients with colorectal cancer mount an immune response to influenza vaccination irrespective of their chemotherapy regimen or timing. However, concurrent responses to all three strains in the individual patient with colorectal cancer are uncommon. The investigation of a booster vaccine in this population is warranted.