The most glaring deficiency was the lack of any comparison between the research test and current colon cancer screening options. The story never mentions what those options are or what benefits/drawbacks the new test might have in relation to them. And the very issue of screening for precancerous polyps vs detection of cancer was not addressed.
As the competing HealthDay story points out, many people do not take advantage of the colon cancer screening options that are currently available to them. At least some of that reluctance has to do with the inconvenience and invasiveness of current tests (not to mention squeamishness on the part of many patients)–issues that could presumably be addressed by a simple breath test like this one.
Costs were not mentioned, but since this test is in an early stage of development, it would be difficult to provide an accurate cost figure. That figure would have to include both the cost of the test and any unnecessary follow-up tests and procedures due to false-positive results. We’ll rule it not applicable.
The story never clearly explained why breath testing would be an advantage over current screening methods, and it didn’t tell what stage of cancer the patients being tested had or whether the test would be useful for detecting precancerous polyps. In addition, as we noted with the competing HealthDay piece, good diagnostic tests not only have to be able to identify people who have a disease correctly, but they also have to be able to rule out people who don’t have the disease correctly. Given that context, it’s unclear what the accuracy statistic provided by the story means. The story says that the test was able to distinguish between the cancer and non-cancer patients 76% of the time. We would have preferred to see the absolute numbers of people in each group (the cancer patients and controls) who were accurately diagnosed, and a comparison of how this stacks up against existing screening methods.
It’s too early to say exactly what harms might result from the use of this test clinically, but at the very least, we know that some patients would be unnecessarily flagged for additional tests and procedures based on a false-positive test. The story should have mentioned this.
The story did make it clear that the test was still in development and might never pan out clinically. However, that was about the extent of the critical evaluation of the evidence. There was almost no discussion of the current study’s methods and limitations.
There was no disease-mongering.
The story quotes an expert who wasn’t involved in the current study. However, since the source is involved in the development of a competing “electronic nose” technology, we don’t think he qualifies as a truly independent voice. Someone with expertise evaluating cancer screening evidence could have probably provided more useful context for readers.
The story did not discuss currently recommended screening practices and their benefits or drawbacks. In addition to colonoscopy and sigmoidoscopy, newer high sensitivity stool testing has good sensitivity and specificity for detecting colon cancers and can be done at home.
It always makes us nervous when a source is allowed to speculate, without reasonable justification, about when an experimental device will be available clinically. And that’s exactly what happened here when an expert said that a breath test for cancer “may be a reality in as little as five years if all goes well.” On the other hand, the story did qualify things quickly when the expert added, “But we are still in the research phase, and there is still the possibility that this technology will never prove clinically useful.” Borderline, but we’ll call it satisfactory.
The story acknowledges that similar technology is being tested for the detection of other cancers.
The story pulls a quote from one of the study authors from this press release, but it acknowledges that the source was “a statement” rather than an interview. It’s clear that reported actually consulted a second expert as well. Another borderline call for which we’ll give the benefit of the doubt.