Cancers in the earliest stage, which have not yet spread beyond the lungs, are divided by size into stage IA (tumors less than 30 millimeters in diameter) and stage IB (tumors larger than 30 millimeters in diameter), according to background information in the article. The development of computed tomography (CT) scanning has allowed physicians to detect lung tumors at a smaller size, prompting some to call for more subdivisions of stage I cancers. Though tumor size has been linked to cancer prognosis in patients with symptoms, the relationship between tumor size, metastasis (cancer spread) and prognosis in asymptomatic individuals has been unclear, the authors write.
Claudia I. Henschke, M.D., Ph.D., New York Presbyterian Hospital–Weill Cornell Medical Center, New York, and colleagues from the International Early Lung Cancer Action Program screened 28,689 men and women for lung cancer at 38 institutions worldwide between 1993 and 2004. Four hundred sixty-four patients were diagnosed with lung cancer as the result of the screening. The researchers classified the participants' lung cancers based on their type--small cell or non–small cell--as well as the size (diameter) of their tumors at diagnosis and whether or not they had metastasized. They also recorded the consistency of the tumors as solid, nonsolid or part-solid.
For the 436 patients with non–small cell cancers, which are less aggressive than small-cell cancers, the likelihood of metastasis increased along with tumor size. When the researchers analyzed the tumors by consistency, they found the association strongest for solid tumors, weaker for part-solid tumors and not apparent for nonsolid tumors. For the few (28) cases of small cell cancer, the relationship appeared strong for those tumors as well. The percentages of nonmetastasized cancer of all types were much higher than those reported in previous studies.
"The pattern confirmed herein suggests the usefulness of finding latent cancers at small sizes," the authors conclude. "Most lung cancers without evidence of lymph node metastases are curable, with the curability rate being higher at smaller sizes. This suggests that tumor diameter also serves as a prognostic indicator for curability, perhaps even for micrometastases not detectable by our current techniques."
(Arch Intern Med. 2006; 166: 321-325. Available pre-embargo to media at www.jamamedia.org.)
Last reviewed: By John M. Grohol, Psy.D. on 21 Feb 2009
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