Lung cancer screening

Why are we not screening for lung cancer?

So began an editorial in a recent edition of 'The Blue Journal'. In this particular edition, an Italian group was reporting on the DANTE trial, which investigated - in a randomised and controlled structure - the use of low dose CT scanning (LDCT) as a screening tool for lung cancer.

Now, although - as previously blogged - lung cancer is the leading cause of cancer death in our community, discussions about lung cancer screening don't rate a mention in the mainstream news. (Contrast this with prostate, breast, cervical and bowel cancer for example).

Efforts to determine whether our new, super-duper, multi-camera CT scanners can be utilised to screen for lung cancer have - to date - fallen over at the first hurdle. While they have demonstrated, repeatedly, that if you perform CT scans on lots of middle-aged smokers you identify lots of asymptomatic, early, curable tumours they have not yet proven that taking out these tumours saves lives.

The recent study has struggled at the same point.

What did they do? A total of 2,472 men aged 60 to 75 years, with at least a 20 pkt year smoking history (a packet a day for 20 years equivalent) were randomised to either a baseline LDCT scan and annual LDCT scans over 5 years, or else a baseline chest xray with annual clinical review. The current data cover follow up over a mean of 33 months (ie not a very long time yet).

What did they find? They found 60 patients (4.70%) with lung cancer in the LDCT group (63 cancers in total - some patients had more than one). Twenty-eight cancers were found in the initial scan ( ie over 2% of these people had cancers they didn't know about to begin with ), 25 were found on subsequent scans and ten were found because people developed symptoms between their annual scans. In the control group, they found 36 cancers in 34 patients; 8 at basline, 3 at routine review and the others because patients developed symptoms.

What did they do next? Lots of intervention! Thirty-nine of the 60 patients in the LDCT arm with cancer had resections, and of these 36 were complete resection. In the control group it was 18 of 34 resected, 17 completely. In the LDCT group there were 96 invasive procedures, vs 36 in the control group. As the investigators put it ''we performed three times as many invasive procedures and found twice as many lung cancer cases with LDCT than without it, ...(but) .. the absolute numbers of advanced and lethal lung cancer cases were unfortunately identical in the two arms.....moreover a significant proportion of major surgical procedures (13%) were performed for pulmonary lesions that ultimately turned out to be benign..."

What happened next after all that intervention? Mortality rates in the groups are identical to date. Put in plain English, the same number of people died in each arm of the study.

So, LDCT screening for lung cancer in asymptomatic patients with no history of cancer detects nearly twice as many cancers as a 'chest xray and annual specialist review' approach, leads to a raft of invasive and expensive interventions, and has not been proven to save any lives. Yet.

Andrew