Lung cancer is associated with very high mortality, in part because it is hard to detect at early stages, but also because it can recur frequently after surgical removal. A common question is what is the best way to follow lung cancer patients after surgery in order to spot problems early enough. A study presented at the recent meeting of the American Association of Thoracic Surgery (AATS) by investigators from the University of Toronto departments of Thoracic Surgery and Diagnostic Radiology show that minimal dose computed tomography (MnDCT) of the thorax offers much greater sensitivity at detecting new or recurrent lung cancer, with equivalent amount of radiation, compared to conventional chest x-rays. “Up to a few years ago, we were using chest x-rays to monitor patients after surgery for lung cancer, but this follow-up was ineffective, and many patients still died of recurrent lung cancer, comments lead investigator Waël C. Hanna. “While CT scans can effectively be used to monitor lung cancer after surgery, there was significant concern about the large amount of radiation that would be delivered to patients, and standard dose CT scans were not used routinely in the follow-up of lung cancer. More recently, new technology allowed us to develop MnDCT.” As reported in the study, the majority of new or recurrent cancers were detected by MnDCT at a subclinical, intrathoracic stage, within two years of surgery. This allowed for the delivery of curative treatment in the majority of patients with asymptomatic cancer and was associated with long survival. The investigators found in their study that MnDCT detected 94% of recurrent cancers compared to only 21% with standard x-rays (p<0.0001). Importantly, the recurrent lung cancer was detected at a much earlier stage, allowing patients to possibly undergo another curative surgery. Detection of a new or recurrent cancer in asymptomatic patients led to further surgery or radiation for 75.5%, while palliative treatment was recommended for the remainder of patients. Survival in the treated group was significantly longer than those who were treated with palliative intent (69 months vs. 15 months, p<0.0001).
“MnDCT offers the best of both worlds: on the one hand it allows for precise imaging close to what is produced from a standard CT scan, and on the other hand it only delivers a small amount of radiation which is comparable to what a regular x-ray would deliver and much less than a standard dose CT scan,” says Dr. Hanna. “More importantly, now we can detect recurrent lung cancer at a much earlier stage, allowing patients to possibly undergo another surgery, and live longer, healthier lives.
The study did find however that MnDCT results produced a higher rate of false positives.