Difficulty swallowing food can be because of various reasons. Esophageal cancer is one of the reasons. That can be diagnosed after upper GI endoscopy
from the suspicious lesion.
As per the recent guidelines, for proper evaluation of esophageal cancer, endoscopy with endoscopic ultrasound
and CT scan
or combined PET-CT
scan is required.
Endoscopic ultrasound is required for adequate evaluation of the tumor (T stage). CT scan or PET-CT scan is required for lymph nodal and distant metastases evaluation (N and M staging)
So when combined together, endoscopic USG and PET-CT provide for the ideal TNM staging of the cancer.
Needless to say, if biopsy doesnt show malignancy, the above mentioned investigations are not required.