In this retrospective study, researchers from the National Cancer Center Hospital in Tokyo, Japan, found that patients with screen-detected lung cancer had better survival than patients whose cancers were identified either incidentally or because they had become symptomatic. The lung cancers in the screened group were characteristically less advanced, had a smaller diameter, and were more frequently diagnosed as adenocarcinoma.
When looking at different modalities of detection, 5-year survival rates for patients screened by CT scan were higher than rates for patients screened by chest x-ray, positron emission tomography (PET), or sputum cytology. The difference in survival between the detection modalities was significant (P = .0127).
Lung cancer is the most common cause of cancer death in Japan, the researchers note, and early detection and surgical resection continue to remain the best possibility for cure. Previous trials using chest x-ray and sputum cytology in heavy smokers have failed to show a reduction in lung-cancer-related mortality, but more recently, several studies have shown that the disease can be detected at a much earlier stage.
Continued Controversy
The efficacy of screening for lung cancers remains controversial, the authors write, and there are no guidelines that currently recommend screening. In particular, evidence for the use of CT scanning for lung cancer is conflicting, as previously reported by Medscape Oncology .
Data from the International Early Lung Cancer Action Project (I-ELCAP), reported in October 2006 in the New England Journal of Medicine (2006;355:1763-1771), were widely publicized in the lay media. The researchers claimed that CT scanning in high-risk populations could prevent about 80% of deaths from lung cancer by detecting the disease in its earliest stages.
However, that study was criticized, and subsequently, a large study published in the Journal of the American Medical Association (JAMA. 2007;297:953-961) refuted the claims that CT scanning improved survival.
At the time, many expert commentators said that no recommendations should be made until large ongoing trials were completed, as reported by Medscape Oncology .
The current study by Hisao Asamura, MD, and colleagues is a retrospective analysis, the authors emphasize, and they too stress the need to wait for data from prospective studies. "For a direct demonstration of the effectiveness of lung cancer screening, we must wait for the results from ongoing randomized control trials, such as the Nederlands Leuvens Screening Onderzoek trial in Europe and the National Lung Screening Trial in North America," they write.
In their study, Dr. Asamura and colleagues attempted to identify the characteristics of lung cancer detected by screening, and to clarify whether patients with screen-detected disease had better survival than those with incidental or symptomatic cancers.
They retrospectively reviewed the records of 2281 patients who underwent lung cancer resection surgery between 2000 and 2006 at the National Cancer Center in Tokyo. Patients were classified into 3 groups, according to the method of detection: screen detected (n = 1290), symptom detected (n = 481), and incidental (n = 568). In the screen-detected group, the researchers analyzed clinicopathological factors according to screening modality used: chest x-ray (n =1136; 82.6%), CT (n = 196; 13.9%), PET (n = 22; 1.6%), and sputum cytology (n = 17; 1.3%).
Improved Survival for Screen-Detected Cancers
When evaluating the characteristics of screen-detected lung cancers, the researchers observed that they were smaller in diameter (<2>
Of screen-detected disease, cancers identified by CT scanning — compared with those identified by chest x-ray or PET-scan — were smaller in diameter (<2>
The team also found that after classifying patients on the basis of diagnostic modality, there was a marked difference in 5-year survival rates. Overall, the 5-year survival rate for the 2281 patients was 75.4%, and 1486 had pathologic stage I nonsmall-cell lung cancer.
5-Year Survival According to Detection Method
| Type of Detection | 5-Year Survival Rate |
| Screen-detected | 79.6% |
| Symptomatic | 74/6% |
| Incidental | 64.6% |
The differences between the 3 groups were statistically significant. In the subgroup with stage I disease, overall survival was 89.6%. Five-year survival rate for screen-detected patients was 92.9%, for symptomatic disease was 84.0%, and for incidental detection was 84.6%.
The 5-year survival rates also differed among screen-detected cases according to the modality used, with CT showing the highest rates.
5-Year Survival of Screen-Detected Lung Cancer According to Modality
| Modality | 5-Year Survival Rate |
| CT | 91.2% |
| Chest x-ray | 77.8% |
| PET | 90.9% |
| Sputum cytology | 80.9% |
In the screen-detected group, 896 patients were diagnosed with stage I nonsmall-cell lung cancer, and of this cohort, 5-year survival for those who underwent CT scanning was 91.7%; for those diagnosed with a chest x-ray, 5-year survival was 81.4%.
Source : http://www.medscape.com/viewarticle/702751?src=mp&spon=34&uac=133298AG
No comments:
Post a Comment