Cancer Research Lab

Incidentally detected lung cancers tend to be smaller and less likely to require removal of a lung, according to a research team at the University of California-San Francisco.

Incidental identification of lung tumors will be more common as imaging for coronary screening, pulmonary embolism, aortic disease, and abdominal pain increases, the investigators note.

As yet, however, screening is not recommended for lung cancer, which may be one reason why lung cancer survival is as low now as it was 30 years ago, whereas survival from other cancers has improved because of routine screening, Dr. Dan J. Raz and his associates note in the Journal of Thoracic Oncology for February.

Dr. Raz and his team identified 274 patients who underwent surgical resection of lung cancer with negative margins at their hospital between 1999 and 2004. Of these, 100 had incidentally detected tumors.

Initially, most indications for imaging were screening chest x-ray, preoperative chest x-ray, staging of another type of cancer, and evaluation of chest symptoms, such as pneumonia and MI. Other reasons included evaluation of non-chest pain, trauma, interstitial lung disease and coronary screening.

“Not surprisingly,” the investigators write, “patients with incidentally detected lung cancer had smaller cancers and earlier-stage disease.” In fact, half of all patients with stage I non-small cell lung cancer had incidentally detected lung cancers.

Of the 23 patients with bronchioloalveolar carcinoma, 65% were detected incidentally, compared with 34% of all other histologic subtypes (p = 0.003). It is not clear whether most of these would remain slow-growing and noninvasive if not treated, the authors note, or if they’re likely to evolve into adenocarcinomas.

As noted, incidental tumors were less likely to require pneumonectomy, which carries greater perioperative morbidity and mortality than lobectomy.

After adjusting for stage, the duration of survival was similar between incidental and symptomatic lung cancers. However, for the 17 lesions detected by computed tomography, the stage-adjusted hazard radio of death was 0.47 for incidental cancers, though the sample size was too small to establish statistical significance.