New study looks at growth rates of lung cancers found by CT screening
Lung cancers diagnosed in annual repeat rounds of CT screening are similar in volume doubling time and cell-type distribution to cancers found in routine practice
- Date : 03 Apr 2012
- Topic : Lung and other thoracic tumours
Growth rates of lung cancers found by annual rounds of computed tomography (CT) screening are important for determining the usefulness and frequency of screening, as well as for determining the treatment. According to the latest report from the International Early Lung Cancer Action Programme (I-ELCAP) published in the journal Radiology, lung cancers diagnosed in annual repeat rounds of CT screening are similar—both in volume doubling time and cell-type distribution— to those found in clinical practice.
There was concern that cancers diagnosed in the screening context were somehow different than cancers found in routine practice, but according to I-ELCAP principal investigator Claudia Henschke, PhD, MD, professor of radiology at Mount Sinai School of Medicine in New York, a new study demonstrated that actually they were not aggressive.
A difference in the growth rates of cancers in solid and sub-solid lesions
I-ELCAP researchers reported that growth rates found in cancers detected in repeat rounds of annual CT screening are not significantly different from growth rates reported for cancers diagnosed in clinical practice in the absence of screening. Also, the frequencies of small-cell carcinoma and adenocarcinoma among all lung cancers have been reported to be approximately 20% and 50%, respectively, in the absence of screening. In repeat rounds of CT screening, these frequencies were nearly identical (19% and 50%).
CT screening has been found effective in detecting lung cancer at its earliest, most curable stage. The first, or baseline, round of screening for any cancer detects a higher proportion of slower-growing cancers than those detected in clinical practice.
The subsequent, repeat rounds of screening, however, reflect what is found in clinical practice. The study found that there is a difference in the growth rates of cancers in solid and sub-solid lesions and that the sub-solid ones tend to be less aggressive than solid ones.
This suggests that a less aggressive approach could be indicated for both diagnosis and treatment of sub-solid lesions.
Review of the I-ELCAP database
The researchers reviewed results from the I-ELCAP database for 1993 to 2009, consisting of men and women at risk for lung cancer who underwent annual repeat rounds of CT screening. The research team identified 111 instances of first primary lung cancer diagnosed either through screening or between rounds after a negative result of the prior screening 7 to 18 months earlier. Of the 111 cancers identified, 88 were clinical stage I. The investigators then analysed volume doubling time and cell-type distribution.
The results showed that the median volume doubling time was 98 days. Most of the cancers, 99 of the 111, manifested as solid nodules, while only 12 of the cancers manifested as sub-solid nodules. Solid nodule cancers had significantly faster volume doubling times than sub-solid nodule cancers. According to Dr. Henschke, identifying the volume doubling times for specific lesion types may lead to more tailored treatment for the patient.
Volume doubling times for lung cancers diagnosed in clinical practice in the absence of screening have been reported to range from 20 to 360 days. A recent study, based on a systematic medical literature review, reported a mean volume doubling time of 135 days for non-small cell lung cancers diagnosed in the absence of screening.
Dr. Henschke recommends that people at high risk for lung cancer have a discussion with their health care provider to discuss the benefits and risks of screening so as to make an informed decision about enrolling in a screening programme.
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