Inclusion Criteria:  ESCC Cases:  Male or female >= 18 years of age at screening visit. Patients are currently seen for clinical care at Muhimbili National Hospital (MNH)-Upanga or at MNH-Mloganzila. Patients with a diagnosis of ESCC as evidenced by histological confirmation. Patient must be able to swallow liquid (Ogilvie's score < 3). Patients must be well enough to participate in a 20-minute interview or have a close relative who is able to do so on their behalf. Patients must be willing to be contacted either in person or via phone 7-10 days following administration of the 'EsophaCap' sponge device. Native of Tanzania. Written informed consent (and assent when applicable) obtained from subject or subject's legal representative and ability for subject to comply with the requirements of the study.  Non-ESCC study participants:  Male or female ≥ 18 years of age at screening visit. Patients are currently seen for clinical care at MNH-Upanga or at MNH-Mloganzila. Patient is scheduled to undergo EGD for a suspected non-malignant condition with no symptoms concerning for esophageal cancer (i.e. dysphagia or odynophagia) Patient must be able to swallow liquid (Ogilvie's score < 3). Patients must be well enough to participate in a 20-minute interview or have a close relative who is able to do so on their behalf. Patients must be willing to be contacted either in person or via phone 7-10 days following administration of the 'EsophaCap' sponge device. Native of Tanzania. Written informed consent (and assent when applicable) obtained from participant or participant's legal representative and ability for subject to comply with the requirements of the study.  Exclusion Criteria:  ESCC Cases:  Known pregnancy during participation in the study. Presence of a condition or abnormality that in the opinion of the Investigator would compromise the safety of the patient or the quality of the data. Clinical instability (i.e. hypotension or a recent cardiovascular event). Any history of upper gastrointestinal bleeding within the past 3 months (including reported history of hematemesis and/or melena). Diagnosis of peptic ulcer disease within the last 3 months. Known history of esophageal varices. Patients taking anticoagulation or antiplatelet therapy/medication (warfarin, clopidogrel, aspirin, heparin or enoxaparin) for high-risk conditions. Patients with an active extra-esophageal malignancy (not currently in remission). Patient with a known history of a non-malignant esophageal stricture. Patients with esophageal stents currently in place. Patients with a history of radiation therapy to the head, neck, any part of the gastrointestinal tract (including esophagus) or thorax. Patients who have previously received chemotherapy in the last 12 months Patients with any history of major surgery for esophageal cancer (e.g. esophageal bypass, esophagectomy, etc.). Patients who have a known history of or clinical symptoms concerning for tracheoesophageal fistula (aspiration history, severe cough) Patients with a known history of small bowel obstruction Patients with a history of bleeding complications during esophageal biopsy performed for histological confirmation. Patients with any history of a head and neck malignancy. Patients with a known bleeding disorder Patients with known thrombocytopenia (less than 50,000 platelets per microliter) Individuals who are not permanent residents or natives of Tanzania. Inability to follow instructions. Unable to provide informed consent.  Non-ESCC study participants:  Known pregnancy during participation in the study. Presence of a condition or abnormality that in the opinion of the Investigator would compromise the safety of the patient or the quality of the data. Clinical instability (i.e. hypotension or a recent cardiovascular event). Any history of upper gastrointestinal bleeding within the past 3 months (including reported history of hematemesis and/or melena). Diagnosis of peptic ulcer disease within the last 3 months. Known history of esophageal varices. Patients taking anticoagulation or antiplatelet therapy/medication (warfarin, clopidogrel, aspirin, heparin or enoxaparin) for high-risk conditions. Patients with an active extra-esophageal malignancy (not currently in remission) or any history of a non-cutaneous malignancy diagnosed within the previous five years. Patient with a known history of esophageal strictures disabling passage of the capsule. Patient with esophageal stents currently in place. Patients with a history of radiation therapy to the head, neck, any part of the gastrointestinal tract (including esophagus) or thorax. Patients with a known history of small bowel obstruction Patients with a known bleeding disorder Patients with known thrombocytopenia (less than 50,000 platelets per microliter) Individuals who are not permanent residents or natives of Tanzania. Allergy to iodine Presence of goiter. Inability to follow instructions. Unable to provide informed consent