Association between severe treatment-related lymphopenia and progression-free survival in patients with newly diagnosed squamous cell head and neck cancer.

Background: Severe treatment-related lymphopenia occurs commonly in many cancers and is associated with early tumor progression. Data are lacking as to whether this occurs in squamous cell head and neck cancer.

Methods: Serial total lymphocyte counts were retrospectively reviewed in patients with newly diagnosed squamous head and neck cancer undergoing chemoradiation and associated with treatment outcomes.

Results: The median baseline total lymphocyte count in 56 patients was 1660 cells/mm(3) , which fell by 73% to 445 cells/mm(3) 2 months after initiating chemoradiation (p < .0001). Human papillomavirus negative (HPV-) patients with a total lymphocyte count <500 cells/mm(3) at 2 months had significantly earlier disease progression than those with higher total lymphocyte counts (hazard ratio [HR], 5.75; p = .045).

Conclusion: Baseline total lymphocyte counts were normal, but at 2 months approximately 60% of patients had severe treatment-related lymphopenia regardless of HPV status. Severe treatment-related lymphopenia in HPV- patients is independently associated with earlier disease progression. Prospective studies are needed to confirm these findings, which suggest that immune preservation is important in this cancer.