Blood Test May Detect Lung Cancer Early

NOTTINGHAM, England, Oct. 10 -- A blood test for tumor antibodies may allow earlier detection of lung cancer, even for node-negative patients, researchers here said.

In a study comparing blood samples, cancer patients were significantly more likely to have antibodies to at least one of a panel of seven tumor-associated antigens than were healthy volunteers, according to Caroline Chapman, Ph.D., of Nottingham City Hospital, and colleagues.

Importantly for early detection, the test picked up eight of nine patients with node-negative disease, Dr. Chapman and colleagues reported online in Thorax.

The study is not the first to suggest that testing for so-called autoantibodies -- those made by the immune system against its own proteins -- might allow for early detection of cancer.

Dr. Chapman and colleagues reported earlier this year, in Annals of Oncology, that higher levels of tumor antibodies were present in the circulation of patients with early invasive breast cancer, and ductal carcinoma in situ.

And a small study in 2003, in Cancer Epidemiology Biomarkers and Prevention reported that a panel of seven autoantibodies (mostly not the same as those used in this study) could be used to detect lung cancer.

Dr. Chapman and colleagues studied blood samples from 104 cancer patients, including 82 with non-small-cell lung cancer and 22 with small-cell lung cancer.

Those samples were compared with blood from 50 healthy volunteers for the presence of antibodies to seven known tumor-associated antigens -- p53, c-myc, HER2, NY-ESO-1, CAGE, MUC1 and GBU4-5.

There were raised levels of antibodies to least one of the seven antigens in 76% of the lung cancer patients, compared with four of the 50 controls (8%). Interestingly, one of the healthy volunteers had antibodies to four of the seven, but no additional clinical data were available for the individual.

The results gave the antigen panel a sensitivity of 76% and a specificity of 92%, the researchers noted.

In almost all cases, the levels of antibody in the blood of patients differed significantly (ranging from P<0.05 to P<0.001) from levels in controls, the researchers found.

The difference was non-significant for p53 in patients with non-small-cell lung cancer and for NY-ESO-1 in small-cell lung cancer, Dr. Chapman and colleagues said.

Indeed, not all of the antigens appeared to be essential for detection, the researchers found. A restricted panel of four -- CAGE, GBU4-5, NY-ESO-1 and MUC1 - had only a slight drop in sensitivity (to 68%) and in increase in specificity (to 94%).

The study shows that testing for a panel of tumor-associated antigens provides an "excellent level of sensitivity for the detection of lung cancer," Dr. Chapman and colleagues said.

Because no clinical information was available for the healthy volunteers, the possibility of underlying malignancy can't be eliminated, the researchers said. But the low level of antibodies seen in this study agrees well with other published research, they added.

Dr. Chapman and colleagues also noted that screening with x-rays is limited, because the lungs are sensitive to radiation. On the other hand, a blood test "is non-invasive, cost effective relative to imaging tests, carries no side effects and is acceptable to the vast majority of patients," they said.