Intensity-Modulated Radiation Therapy, Pemetrexed, and Erlotinib in Treating Patients With Recurrent or Second Primary Head and Neck Cancer

Inclusion: \* Histologically or cytologically confirmed diagnosis of recurrent or second primary squamous cell carcinoma (SCC) of the head and neck, including any of the following: * Oral cavity * Oropharynx * Hypopharynx * Larynx * Recurrent neck metastases with unknown primary Exception from pathology confirmation of tumor recurrence is accepted for patients who originally had pathologically confirmed SCC of the Head and Neck, the new tumor is located in the head and neck area and it is clinically considered as a recurrence of the original tumor, and a tumor biopsy is technically difficult and would expose the patient to unjustified risk. The treating physicians should agree and document the clinical definition of tumor recurrence and should document the increased risk for biopsy. * Measurable disease by CT scan or MRI OR evaluable disease * No definitive evidence of distant metastasis * Unresectable disease by a preliminary ENT evaluation OR refused surgery * Patients may have received chemotherapy as a component of their primary tumor treatment but not for recurrent or metastatic disease. No prior treatment with systemic anti-EGFR inhibitors or Pemetrexed is permitted * Has undergone prior head and neck radiotherapy (for SCC of the head and neck) to a dose of ≤ 72 Gy that involved most of the recurrent tumor (\> 75%) OR has a second primary tumor volume in areas previously irradiated to \> 45 Gy * The entire tumor volume must be included in a treatment field that limi…