Physical Fitness in Ambulatory Patients with Chronic Lymphoid Malignancies Receiving Monoclonal Antibody-Based Therapy: A Case–Control Study

Introduction: Hematologic malignancies account for a significant proportion of the global cancer burden. Immunotherapy is currently one of the key treatment modalities used in the management of these diseases. Objective: This study aimed to assess the physical fitness of patients with chronic lymphoid malignancies receiving monoclonal antibody-based therapy compared with healthy individuals. Materials and Methods: The study included 99 ambulatory patients being treated for hematologic malignancies—33 with chronic lymphocytic leukemia, 32 with multiple myeloma, and 34 with follicular lymphoma—as well as 43 healthy individuals. All participants underwent the Two-Minute Step Test, the 30-Second Sit-to-Stand Test, and the Timed Up and Go Test. Results: Patients with hematologic malignancies, regardless of diagnosis, were characterized by significantly lower lower-limb strength (H(3, N = 142) = 24.779, p < 0.0001), as well as poorer agility and dynamic balance (H(3, N = 142) = 24.993, p < 0.0001). Patients diagnosed with multiple myeloma and follicular lymphoma also exhibited lower cardiorespiratory endurance (H(3, N = 142) = 13.223, p = 0.0042). Age was a significant predictor of physical fitness. However, in an analysis treating diagnosis as a categorical variable with the control group as the reference category, patients with hematologic malignancies also had significantly lower physical fitness scores than controls. Conclusions: Patients with chronic lymphoid malignancies receiving monoclonal antibody-based therapy exhibit reduced physical fitness regardless of hematologic diagnosis. Patient age is an additional factor associated with physical fitness.