Low Dose Lung CT Finds More Cancers in Surgery Patients

Minimal dose computed tomography detected 96 percent of new or recurrent lung cancers in patients who had undergone resection of lung cancer, compared with 21 percent detected using chest X-ray, according to the results of a study presented at the recent 93rd AATS Annual Meeting.

“Patients who have had surgery to remove a lung cancer in the past are among the highest risk to get a new cancer in the future,” said Waël C. Hanna, MDCM, of the Department of Thoracic Surgery at the University of Toronto. “Prior to this study, we followed them with chest X-rays, but could only detect a small minority of patients with new lung cancer, in time to offer them curative surgery again.”

In the study presented at the meeting, Hanna and colleagues followed patients who had lung cancer surgery with minimal dose computed tomography (MnDCT). According to Dr. Hanna, MnDCT offers superior imaging, but subjects patients to a dose of radiation that is equivalent to that experienced during a regular chest X-ray.

The study included 311 patients who had undergone curative resection of lung cancer. All patients underwent surveillance with MnDCT and chest X-ray at three, six, 12, 18, 24, 36, 48 and 60 months. Radiologists blinded to the imaging modality interpreted the images looking for new or recurrent cancer. When cancer was suspected, a full-dose CT or biopsy was performed.

MnDCT had a higher sensitivity for detecting new or recurrent cancers (96 percent vs. 21 percent; P<.001). The modality also had a higher negative predictive value (99 percent vs. 95 percent; P=.007).

“We were not surprised by these numbers,” Hanna said in an interview. “However, the surprising finding was that in 75 percent of these patients, the new lung cancer was detected at a very early stage, where we can intervene and offer further curative life-prolonging treatment.”

A majority of patients diagnosed with new or recurrent cancers were asymptomatic. Seventy-six percent of these patients were treated with curative intent surgery or radiation and had a median survival of 69 months. Patients who did not undergo surgery received palliative care and had a median survival of 25 months.

“We believe that this study is going to change practice in terms of how we follow lung cancer,” Hanna said. “We will start using MnDCT instead of chest X-ray, because it offers superior imaging for the same radiation dose, and because it allows for early detection and cure of recurrent lung cancer.”

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