This is a study conducted in patients with a diagnosis of stage IB-IVA squamous cell carcinoma of the head and neck. Patients will have a comprehensive geriatric assessment (CGA) as part of standard assessments. The patients classified as frail, with a CGA score of 3-5, will then be treated with a novel reduced intensity regimen. The regimen will be tailored based on the programmed cell death ligand 1 combined positive score (PD-L1 CPS) and will involve 4 cycles of systemic chemotherapy and/or immunotherapy followed by radiation treatment.

See above summary.

Inclusion Criteria:

• Patients must have the following
• Pathology confirmed squamous cell carcinoma of the head and neck (unknown primary is excluded).
• Confirmed stage of disease between IB and IVA, based on imaging studies.
• CGA score of 3-5
• Evaluation by medical oncology and radiation oncology.
• Patients in the experimental group must be eligible for systemic treatment with chemoimmunotherapy followed by radiation treatment as determined by the geriatric oncology team.
• Age ≥ 65 years.
• ECOG performance status ≤ 2
• Adequate organ and marrow function as defined below:

Absolute neutrophil count ≥1.0 x 109/L Platelets >100,000/mm3 Total bilirubin <1.5 x ULN Aspartate aminotransferase (ast/sgot) <3 x ULN Alanine aminotransferase (alt/sgpt) <3 x ULN Creatinine clearance ≥ 40 mL/min as determined by Cockcroft Gault (using actual body weight) or <1.5 x Upper limit of normal

Males:

CLcr (mL/min) = "[140 - age (years)] × weight (kg)" /"72 × serum creatinine (mg/dL)"

Females:

(CLcr (mL/min) = "[140 - age (years)] × weight (kg)" /"72 × serum creatinine (mg/dL)" × 0.85

• Patients receiving pembrolizumab must meet standard institutional criteria for immunotherapy including no history of severe autoimmune disease.
• Human immunodeficiency virus (HIV)-infected patients on effective anti-retroviral therapy with undetectable viral load within 6 months are eligible for this trial.
• For patients with evidence of chronic hepatitis B virus (HBV) infection, the HBV viral load must be undetectable on suppressive therapy, if indicated.
• Patients with a history of hepatitis C virus (HCV) infection must have been treated and cured. For patients with HCV infection who are currently on treatment, they are eligible if they have an undetectable HCV viral load.
• Patients with metastases, including treated brain metastases, are not eligible for enrollment.
• Patients with a prior or concurrent malignancy whose natural history or treatment does not have the potential to interfere with the safety or efficacy assessment of the investigational regimen are eligible for this trial.
• Patients with known history or current symptoms of cardiac disease, or history of treatment with cardiotoxic agents, should have a clinical risk assessment of cardiac function using the New York Heart Association Functional Classification. To be eligible for this trial, patients should be class 2B or better.
• Ability to understand and the willingness to sign a written informed consent document.

Exclusion Criteria:

• Patients who have previously received systemic chemoimmunotherapy for H/N cancer.
• Patients with uncontrolled intercurrent illness.