Cancer Research Lab

Overdiagnosis is common in computed tomography (CT) lung cancer screening, according to a report in the February issue of Radiology.

“Screening high-risk patients with chest CT may result in lung cancer overdiagnosis, especially in women,” Dr. Rebecca M. Lindell from the Mayo Clinic, Rochester, Minnesota said.

Dr. Lindell and associates evaluated the size, morphology, location, morphologic change, and growth rate of new and existing lung cancers detected in high-risk individuals who underwent annual screening chest CT for 5 years.

Sixty-one tumors were diagnosed in 1520 participants in the lung cancer screening study, the authors report. Thirty-one were incidence tumors and 30 were prevalence tumors.

The new cancers detected by CT were most commonly non-bronchoalveolar adenocarcinomas, the investigators say.

Mean volume doubling time in the 48 tumors that could be assessed was 518 days, the results indicate. The 13 tumors with a volume doubling time longer than 400 days were stage IA (10 tumors), IB (1 tumor), or II (2 tumors).

Eleven of the 13 overdiagnosed tumors (that is, those with a volume doubling time in excess of 400 days) occurred in women, the report indicates.

Tumors were more commonly detected in the right lung than in the left lung, the researchers note, and most tumors were in the upper lobes.

“Overdiagnosis, especially in women, may be a substantial concern in lung cancer screening,” the authors conclude.

“The effectiveness of lung cancer screening hasn’t been proven; therefore, one can not assess the cost-effectiveness yet,” Dr. Lindell added.