Esophageal Cancer

Fast Facts:

• 1% of U.S. cancers (much higher incidence in other parts of the world)
• Male > female (3-4:1)
• 1:125 men affected in U.S.

Types:

• Squamous Cell Carcinoma: Usually affects upper 2/3 of esophagus.
• Adenocarcinoma: Usually arises in the lower 1/3 of esophagus (typically associated with chronic inflammation secondary to gastroesophageal reflux).

Indications for PET/CT Scan: 

Nearly every esophageal cancer patient presenting for PET/CT imaging already has a biopsy-proven diagnosis. Occasionally, however, an incidental esophageal cancer is found. 

Initial Staging: 

• Currently, initial staging is best performed by a combination of upper endoscopy (including endoscopic ultrasound) and PET/CT, to assess resectability and the role of neoadjuvant chemoradiation.
• Endoscopy and EUS are better at evaluating both lesion size and degree of invasion.  EUS may also have greater sensitivity for small adjacent paraesophageal nodes.
• The utility of PET/CT lies in its assessment of regional and distant metastatic disease.
  • Regional Nodes:
    • Upper Esophagus: Cervical nodes.
    • Lower Esophagus: Mesenteric nodes.
  • Distant Disease: Most commonly to the liver, lungs and bone.

Assessing Response to Therapy & Prognosis: 

• Early Response: Non-responders can be offered alternative therapy.
• Late Response: Assess success or failure of therapy, and ultimate outcome.
• NOTE: A negative post-neoadjuvant therapy PET/CT scan cannot completely exclude residual underlying active disease. Esophagectomy is still typically required.

Recurrence & Restaging: 

• Restaging suspected recurrence.
• Distinguishing recurrence from post-therapeutic inflammation.

Criteria for “Active Malignancy”:

• Any focus of increased metabolic activity involving the esophagus should raise a suspicion for malignancy. 
• An accompanying well-defined soft tissue abnormality will not always be detected on the co-registered CT images.
• The more focal and the more intense the uptake, the more likely the lesion is to be malignant.
• The presence of associated hypermetabolic nodes dramatically increases the likelihood of malignancy.
• Diffuse uptake is presumed inflammatory or physiologic (discussed here).

False Positives:

• Inflammation: May be diffuse or distal, typically due to reflux esophagitis.
• Radiation-Induced Esophagitis: The effects of radiotherapy can induce focal or segmental areas of intense uptake lasting 3-months or longer.
• LES: Uptake at the lower esophageal sphincter typically represents normal physiologic muscle uptake.
• Hiatal Hernia: Increased metabolic activity is frequently encountered within a hiatal hernia. Such uptake is nearly always physiologic or inflammatory (discussed here). Malignancy, however, sometimes cannot be excluded and upper endoscopy may be required.
• Post-Surgical Inflammatory Changes: Typically seen at anastomosis sites. May require follow-up to exclude disease.
• Benign strictures status-post dilatation can be intensely avid.

False Negatives:

• Lesions less than 8.0 mm: These very small lesions may have minimal or no appreciable uptake, as they are “beneath the resolution of PET”.
• Small adenocarcinomas can have poor avidity (possibly due to mucinous elements).
• Small FDG-avid para-esophageal nodes can be masked by superimposed uptake from the primary lesion.