Finnish investigators recently reported that
the survival rates of patients whose lung cancer was found during
screening with a single chest radiograph were significantly higher
than survival rates in patients whose cancer was detected through
the ordinary health care system. Their study was
published in Chest, the journal of the American College of
Chest Physicians (ACCP).
In this study, 290,000 men underwent screening for cancer as part of
a large cancer prevention study in southwestern Finland. Those who
were found to have cancer were excluded from the study.
A total of 93 of the excluded participants were found to have lung
cancer as a result of a single chest radiograph and became the
screened or study group in an investigation headed by Dr.
Elja-Riitta Salomaa of Turku University Hospital in Preitila,
Finland. These men were compared with 239 men in the same age range
whose lung cancer was detected in what researchers described as the
ordinary health care system or other cases. These men
were identified through the local hospital discharge register. Of the
239 patients, 74 had their cancer detected by chest radiographs taken
to control diseases other than lung cancer.
The premise of the study was that lung cancer prognosis is better if
the diagnosis is made early when the disease is still localized and
is curable with radical surgery.
Differences Between Screened and Other Cases Groups
There were differences between the screened and the
other cases groups. For example, 91% of those in the
screened group smoked, as compared with only 58% of the other cases
group. Also, the cancer found in the screened group was more limited.
The treatment of lung cancer was also different in the two groups.
Radical surgery was performed in 37% of men with lung cancer in the
screened cases group and in 19% of men with lung cancer in the other
cases group. In both groups, 48% of the men were treated with
radiotherapy or chemotherapy.
Survival rates were almost twice as good in the screened group as in
the other cases group: 19% of men in the screened group and 10% of
men in the other cases group were alive 5 years after diagnosis.
Investigators noted that if those in the others group who
had chest radiography were excluded from the analysis, the difference
in survival rates between the two groups would be even greater. They
emphasized, however, that there were several factors that were only
partly controlled for, and that the results should be interpreted cautiously.
Interpreting the Data
In an accompanying editorial in Chest, Gary Strauss, MD, of
the Dana-Farber Cancer Institute at Harvard Medical School, pointed
out that the study may be subject to some biases, including that of
patient selection. At the same time, he noted that the results of the
study cannot be completely explained on the basis of selection bias
because the results confirm the major findings of four randomized
Dr. Strauss added that these results (also) provide powerful
evidence that chest radiography screening does not lead to the
overdiagnosis of lung cancer. He added: Proper
interpretation of cancer early detection trial is exceedingly
complex. However, the significant stage distribution, resectability,
and long-term survival advantages reported in this new study, which
confirm similar findings from randomized population trials, represent
solid evidence that chest radiography screening can save lives.