Minimal dose CT superior to chest X-ray for detection of recurrent lung cancer eInterview with Dr. Waël C. Hanna
University of Toronto departments of Thoracic Surgery and Diagnostic Radiology, What are the main findings of the study?

Dr. Hanna: By using Minimal Dose CT Scan (MnDCT) for surveillance of patients after lung cancer resection, we can detect 94.2% of recurrent or new lung cancer in this patient population. When we use chest x-ray (CXR) to conduct surveillance on the same cohort of patients, we can only detect 21.1% of new or recurrent lung cancer cases. Therefore, while MnDCT scan subjects the patient to a similar effective dose of radiation as CXR (0.2 mSV vs. 0.16 mSv), it is a vastly superior test for follow-up of this high risk population. More importantly, when we use MnDCT for surveillance, we can detect new or recurrent lung cancer at the asymptomatic locoregional stage in 78% of patients, and there quarters of those patients are candidates for further treatment in the form of surgery or radiation. In the patients who were treated, median survival was 69 months after initial operation, versus 25 months in those who received no treatment. Were any of the findings unexpected?

Dr. Hanna:

The efficacy of CT scan was expected, but the effect on survival was not. What should clinicians and patients take away from your report?

We believe that based on this data, MnDCT should become the modality of choice for surveillance of patients after lung cancer resection, because recurrences that are diagnosed by MnDCT are amenable to further treatment and this is associated with long survival. What recommendations do you have for future research as a result of this study?

Dr. Hanna: Future research should focus on the ideal intervals of surveillance with MnDCT, the cost implications of this surveillance regimen, and a longer follow-up to document longer term survival benefits.


Minimal dose CT superior to chest X-ray for detection of recurrent lung cancer
Presented at 2013
93rd American Association for Thoracic Surgery Annual Meeting

Press Release: May 6 2013

Minimal dose CT superior to chest X-ray for detection of recurrent lung cancer

Greater sensitivity, with lower radiation dose, allows for faster treatment, reported at 93rd AATS Annual Meeting

Minneapolis, MN, May 6, 2013 – 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. The question arises as to what is the best way to follow lung cancer patients after surgery in order to spot problems early enough, before symptoms become obvious, so that patients may still be eligible for new interventions. In this study presented at the 93rd AATS Annual Meeting, 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, MDCM, MBA, of the Department of Thoracic Surgery at the University of Toronto. “While CT scans can effectively be used to monitor lung cancer after surgery, there was significant concern about the large amount of radiation that will 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 this study, the majority of new or recurrent cancer was 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 study followed 271 patients with lung cancer (80% Stage I, 12.5% Stage II) who underwent curative resection of lung cancer. Repeated imaging occurred at 3, 6, 12, 18, 24, 36, 48 and 60 months using both standard chest x-rays and MnDCT.

Investigators found 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 that MnDCT results produced a high rate of false positives, and the need for surgeons to be alert to this limitation in order to make correct clinical judgments regarding follow-up treatment.

May 6 2013

Last Updated on May 7, 2013 by Marie Benz MD FAAD