PET Imaging May Help Guide Treatment of Esophageal and Gastric Cancers

PET Imaging May Help Guide Treatment of Esophageal and Gastric Cancers

According to the results of a study published in Lancet Oncology, use of positron emission tomography (PET) imaging to evaluate response to neoadjuvant (before surgery) chemotherapy may help guide treatment of patients with cancer of the lower part of the esophagus or the upper part of the stomach (adenocarcinoma of the esophagogastric junction).

For patients with operable, locally advanced adenocarcinoma of the lower esophagus, stomach, or esophagogastric junction (the area where the esophagus joins the stomach), a Phase III clinical trial indicated that chemotherapy before and after surgery may improve outcomes.[1] Not all patients respond to chemotherapy, however. Being able to identify early in the course of treatment those patients who are not responding to chemotherapy would allow these patients to stop chemotherapy early and proceed more quickly to surgery.

Positron emission tomography is an imaging technique that is sometimes used to help stage cancer. Prior to a PET scan, a substance containing a type of sugar attached to a radioactive isotope (a molecule that spontaneously emits radiation) is injected into the patient’s vein. The cancer cells “take up” the sugar and attached isotope. The low energy radiation emitted by these cells helps physicians locate cancer.

To evaluate the use of PET for assessing early response to neoadjuvant (before surgery) chemotherapy, researchers conducted a Phase II clinical trial among 110 patients with locally advanced adenocarcinoma of the lower esophagus or the upper part of the stomach.[2] Patients were assessed by PET prior to the start of neoadjuvant chemotherapy and after the first two weeks of neoadjuvant chemotherapy. A comparison of the two scans allowed physicians to assess which cancers were responding to chemotherapy.

Patients who responded to chemotherapy (as assessed by PET) continued on chemotherapy for a total of 12 weeks. Patients who did not respond to chemotherapy stopped chemotherapy after the first two weeks and proceeded directly to surgery.

  • 49% of patients were classified as chemotherapy responders on the basis of their PET results.
  • Median survival without cancer relapse was 29.7 months in the chemotherapy responders and 14.1 months in the chemotherapy nonresponders. The survival among the chemotherapy nonresponders was similar to the survival noted in a previous study in which nonresponders continued on chemotherapy; this suggests that stopping chemotherapy early in the nonresponders did not have an adverse effect on treatment outcomes.

The researchers conclude that use of PET to monitor chemotherapy response is feasible in patients with adenocarcinoma of the lower esophagus or upper stomach, and may allow for more individualized treatment. Early identification of patients who are not responding to chemotherapy may allow these patients to avoid unnecessary side effects and to consider other treatment options. The researchers note, however, that Phase III clinical trials will be necessary to further evaluate these issues.

References:

[1] Cunningham D, Allum W, Stenning S, et al. Perioperative Chemotherapy Versus Surgery Alone for Resectable Gastroesohpageal Cancer. New England Journal of Medicine. 2006 ; 355:11-20.

[2] Lordick F, Ott K, Krause B-J et al. PET to assess early metabolic response and to guide treatment of adenocarcinoma of the oesophagogastric junction: the MUNICON phase II trial. Lancet Oncology. 2007;8:797-805.

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