According to results recently published in the journal Cancer, fluorodeoxyglucose positron emission tomography (FDG-PET) scans appear to improve accuracy of staging in esophageal cancer over computed tomography (CT) scans alone, particularly in the detection of cancer spread to lymph nodes and distant sites in the body.
The esophagus is a tube that connects the mouth and the stomach. Cure rates for esophageal cancer depend upon its extent of spread; however, overall long-term survival for most patients with esophageal cancer remains poor. The accurate determination of the extent of spread, or the stage, of esophageal cancer is imperative, as the stage dictates treatment options. Types of scans, such as computer tomography (CT) scans, or procedures such as ultrasound, may be used to determine how far cancer has spread in a person or to what areas of the body the cancer has spread. However, often these procedures are not able to detect some areas of cancer spread, leaving patients with suboptimal therapeutic choices for their true stage of cancer. Since long-term survival for esophageal cancer remains poor, researchers continue to compare screening procedures to ensure patients are receiving the most accurate screening methods to determine their stage of cancer..
PET scans are being evaluated in the staging of esophageal cancer, in an attempt to improve upon staging accuracy determined by CT scans, the most commonly utilized staging procedure for esophageal cancer. PET scans utilize a combination of sugar and a radioactive isotope (molecule that spontaneously and continuously emits radiation for a specified period of time) to detect cancer cells in the body. The mixture is injected into a patient’s vein and tends to accumulate in cancer cells, rather than normal cells, as cancer cells have a higher rate of metabolism. The radioactivity is then picked up on a screen, indicating the presence of cancer cells. The main criticism of PET scans versus CT scans is the increased expense of PET scans. Because of the added expense, it is important that studies show clear benefit before being routinely adopted.
Researchers from Japan recently conducted a clinical trial evaluating the effectiveness of PET scans in determining the stage of patients with esophageal cancer. The trial included 149 patients who underwent a PET scan and a CT scan within one month of each other. Overall, PET scans identified 80% of the original cancer. Accuracy in staging according to cancer spread to the lymph nodes was 72% for PET scans, compared with 63% for CT. Results from PET scans also correctly identified 6 patients with cancer spread to distant sites in the body that CT had not identified. The effectiveness of staging accuracy with the addition of PET results increased by 14% compared to CT results alone.
The researchers concluded that the combination of CT and PET may be the most effective combination in staging of esophageal cancer, particularly in staging for cancer spread to the lymph nodes and distant sites in the body. Future clinical trials will undoubtedly be ongoing to evaluate combinations of screening methods for optimal staging of esophageal cancer. Patients diagnosed with esophageal cancer may wish to speak with their physician regarding their individual risks and benefits of PET scans.
Reference: Kato H, Miyazaki T, Nakajima M, et al. The incremental effect of positron emission tomography on diagnostic accuracy in the initial staging of esophageal carcinoma. Cancer. 2005; 103:148-156.