Serologic Response to Pneumococcal Vaccination Among Esophageal Cancer Patients With High Grade Lymphopenia After Chemoradiation

This study looks at how well people with esophageal (food pipe) cancer respond to pneumococcal (pneumonia) vaccines while undergoing chemotherapy combined with radiation therapy. Some patients develop low white blood cell counts (lymphopenia) during this treatment, which weakens the immune system. The study examines whether vaccinations are still effective under these conditions. **You may be eligible if...** - You have esophageal cancer and are receiving or have recently completed chemoradiation treatment - You are treated at the participating medical center - You are able to receive a pneumococcal vaccine as part of normal preventive care **You may NOT be eligible if...** - You have a prior immune system disorder that would interfere with vaccine response - You are unable to receive vaccines for medical reasons - You have already received a pneumococcal vaccine recently (within time limits specified by the study) Talk to your doctor to see if this trial is right for you.