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Size of Lung Tumor Does Not Always Reflect Cancer Severity

Size of Lung Tumor Does Not Always Reflect Cancer Severity

A fundamental assumption of lung cancer screening is
that small tumors are less likely to have metastasized than large tumors.
However, in a new study conducted at Duke Comprehensive Cancer Center,
researchers showed that size does not necessarily indicate the severity of the
cancer.

The authors of the study, based on the stage distribution of cancer in 620
men and women with primary non-small-cell lung carcinomas, caution physicians
who have begun to use computed tomography (CT) scans for screening and early
lung cancer detection not to assume that small tumors represent early-stage
cancer. They advise physicians against the widespread use of CT scans for
screening and early detection of lung cancer until further data become
available.

"Our study found no statistically significant relationship between the
size of small tumors and the stage of cancer," said Dr. Edward F. Patz, Jr,
professor of radiology at Duke University Medical Center and senior author of
the article appearing in a recent issue of the journal Cancer (92:3051-3055,
2001).

Smaller Tumors and Advanced Disease

The study focused on patients with tumors that measured from less than
1 cm to 3 cm in size. Researchers concluded that even the smaller tumors
could represent an advanced stage of disease. They said that their study
suggested that the size of tumors less than or equal to 3 cm played only a
limited role in the biology of lung cancer. Patients with a primary lesion that
is 3 cm or smaller in diameter will have an approximately 80% to 85% chance of
having stage I lung cancer and an approximately 10% chance of having stage IV
lung cancer, regardless of tumor size at detection.

In recent years, low-dose spiral CT scans have been proposed as a potential
method to screen for lung cancer. Proponents of CT scans have argued that these
scans could detect smaller lesions not visible with chest x-rays, that these
smaller tumors represented an early stage of cancer, and that detecting them
would lead to reduced lung cancer mortality, said the Duke researchers.

"Our study emphasizes the fact that size alone does not appear to
determine a cancer’s metastatic potential and ultimate stage
distribution," said the researchers. "While it is reassuring to
believe there is a size threshold below which there is minimal or reduced risk
of a tumor having metastasized, and thus that lung cancer screening can reduce
mortality, there are no conclusive data to support this notion. Early detection
with imaging alone may not be enough to impact the natural course of lung
cancer."

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