Comparison of computed tomograms taken during the first 31 days of chemotherapy with pre-treatment images can detect which non-small cell lung cancers will progress and which will respond to chemotherapy, according to a presentation at the annual meeting of the American Roentgen Ray Society.

The study, led by Dr. John F. Bruzzi of MD Anderson Cancer Center in Houston, TX, was done to determine whether short-term follow-up computed tomography in patients with non-small cell lung cancer can detect significant changes in tumor size due to disease progression or response to therapy.

The study, which was performed within a 31-day time period, had 41 adults ranging from 26 to 85 years of age. Short-term restaging scans in each patient comprised at least two serial studies performed during this time period.

A significant change in tumor size was observed in 7 patients, 4 of whom had poorly differentiated tumors. There was a 33 percent decrease in tumor size in 1 patient in response to chemotherapy. In 5 patients, tumors increased extensively in size by 20 to 48 percent over a period of 31 days or less. This prompted either a change or discontinuation of chemotherapy in all 5 patients.

"We found that 17 percent of patients with non-small-cell lung cancer being treated with chemotherapy had a significant change in tumor size on restaging computed tomography (CT) performed within 31 days of their baseline CT scan," said Bruzzi.

"Twelve percent of these patients had tumor progression, while 3 percent had tumor shrinkage. This response occurred regardless of initial tumor stage, tumor histology or type of treatment received. This means that an early restaging CT that detects tumor progression can allow the clinician to change or discontinue chemotherapy earlier than might otherwise be done, thereby helping to reduce exposure of the patient to costly and potentially toxic chemotherapy agents that are ineffective; it also gives greater confidence to the clinician in continuing therapy that is producing a good tumor response," said Bruzzi.

"We believe now that the value of performing early restaging CT should be assessed in a controlled prospective study of a more homogeneous population of patients with lung cancer, which could perhaps also incorporate volumetric measurements of tumor size and assess the relative values of restaging CT and CT-PET scanning," concluded Bruzzi.