Up to 4 years of annual chest radiographic screening did not reduce
cumulative lung cancer mortality during 13 years of follow-up in a randomized
screening trial of nearly 155,000 participants.
From November 1993 to July 2001, 77,445 participants aged 55 to 74 years
were randomly assigned to annual screenings in the
Prostate, Lung, Colorectal and Ovarian Cancer Screening Trial
(PLCO). Another 77,456 were assigned to usual care.
About 45% of participants in both groups were never smokers, 42% former
smokers and 10% were current smokers.
Cumulative incidence rate for cancer through 13 years was 20.1/10,000
person-years in the intervention group and 19.2/10,000 person-years in the
usual-care group (RR=1.05; 95% CI, 0.98-1.12). Within the intervention group,
61% of lung cancers were screen-detected and 39% were detected during the
interval, indicating that 18% of total lung cancers were detected by screening
and 12% were interval cancers, according to the researchers.
There were 1,213 cancer deaths in the intervention group vs. 1,230 in
the usual-care group. Cumulative lung cancer mortality rate was 14/10,000
person-years in the intervention group and 14.2/10,000 person-years in the
usual-care group (RR=0.99; 95% CI, 0.87-1.22).
Primary treatment was similar overall and by stage in both groups.
Total overall deaths were nearly identical: 11.7% in the intervention
group vs. 11.9% in the usual-care group. Cumulative mortality rate from other
causes were 105.2/10,000 person-years in the intervention group and
107.1/10,000 person-years in the usual-care group (RR=0.98; 95% CI,
0.95-1.01).
In an accompanying editorial, Harold C. Sox, MD, professor of
medicine with Dartmouth Medical School and the Dartmouth Institute, said the
results show definitively that "a short-term chest radiography screening
program has no effect on
lung
cancer mortality."
"The PLCO lung cancer study result provides convincing evidence that
lung cancer screening with chest radiography is not effective," Sox wrote. "The
study is important for putting this question to rest and providing strong
empirical grounds for comparing low-dose computed tomography to a real-world
alternative: usual care."
This study emphasizes the fact that chest radiographs don't save lives in lung cancer and they don't detect cancer reliably at an earlier stage. Chest X-rays are not an effective screening tool for lung cancer.
The National Comprehensive Cancer Network has just updated its guidelines on prevention to recommend advising low-dose CT screening for patients who meet criteria from the National Lung Screening Trial: heavy smokers and people aged 55 to 74 years who have quit within the previous 15 years. By the time someone has symptoms from lung cancer, it is very likely they have late stage disease.
- Rita S. Axelrod, MD
Kimmel Cancer Center, Philadelphia
Disclosure: Dr. Axelrod reports no relevant financial disclosures.