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Waiting too long to challenge claims of “perfect accuracy” in a pancreatic cancer test

Rating

3 Star

A blood test for pancreatic cancer may re-stack the odds in patients' favor

Our Review Summary

This article describes the discovery of a molecule that points to the presence of glypican-1, a protein that is expressed in pancreatic and breast cancer, and how the protein might serve as a marker for earlier diagnosis of pancreatic cancer. It presents a clear overview of the method researchers used to detect the protein and includes an independent expert which gives the story balance. The story would have been stronger with a nod to the potential cost and harms of screening tools, and with a more aggressive challenge to the claim that the test has “perfect accuracy.”  We also reviewed stories published by NBCNews.com the Houston Chronicle on this same discovery.

 

Why This Matters

By the time it is diagnosed, pancreatic cancer is often too far advanced to respond to treatment. A screening tool that would allow earlier detection and treatment could potentially save lives. There currently is no specific screening test that can reliably detect early-stage pancreatic cancer in people who have no symptoms, according to the American Society of Clinical Oncology.

Criteria

Does the story adequately discuss the costs of the intervention?

Not Satisfactory

The story doesn’t mention costs of the screening tool, should one be developed. Costs for screening tests vary widely.

Does the story adequately quantify the benefits of the treatment/test/product/procedure?

Not Satisfactory

The description of benefits could have been stronger. The article states that researchers have found a way to identify the presence of a protein that indicates pancreatic cancer “with perfect accuracy and no false positives.” That’s technically true in this study, but it’s only part of the story. As the story notes, the main benefit of the test would be its ability to detect cancer at an early, treatable stage. But the study included only 5 patients with such early stage cancers — something the story didn’t explicitly tell us. While experts quoted in the article urge caution in reading too much into a small study, the claim of “perfect accuracy,” based on such a tiny sample, deserved a more aggressive and immediate challenge. It isn’t until the very end of the story that any caveats are introduced. In addition, while patients who are able to undergo early treatment might be cured of the disease, the NCI cancer summary points out that the 5-year survival rate for patients who underwent complete resection for small tumors that were confined to the pancreas (the target for screening) was still only 18 to 24%. So, patients may still face long odds even when their tumors are caught early — context the story could have provided.

Does the story adequately explain/quantify the harms of the intervention?

Not Satisfactory

This article, like others covering the study that we reviewed, ignored the potential harms from screening tests. In the real world, all screening tests carry the risk of false negatives, false positives and inconclusive results that could lead to more invasive tests and over-aggressive treatments.

Does the story seem to grasp the quality of the evidence?

Satisfactory

The article provides a clear explanation of how researchers identified the protein and the methods they used to measure it. The story also defines the number of volunteers (251 with pancreatic cancer, 32 with chronic pancreatitis and 120 health controls). While we’re concerned with the story’s assertion that the presence of the protein provides “perfect accuracy and no false positives” in diagnosing pancreatic cancer, we’ve already addressed that issue above under Benefits. We’ll give credit here for the story’s inclusion of cautionary statements, such as that that this was a small cohort and that the study should be repeated in a larger group of volunteers.

Does the story commit disease-mongering?

Not Satisfactory

The problem here isn’t egregious, but the story does refer to pancreatic cancer as one of the “common cancers” in the United States, which is not accurate. Pancreatic cancer isn’t in the Top 10. The most common cancers in the U.S. are breast, cervical, colorectal, HPV-associated, lung, ovarian prostate, skin, uterine and vaginal and vulvar, according to the Centers for Disease Control.

As we noted in a review of an NBCNews.com article on this research, it’s important to present statistics in context. That story was lauded for including an important caveat: “For perspective, over the course of a lifetime, 1.5 percent of Americans will develop pancreatic cancer.”

Does the story use independent sources and identify conflicts of interest?

Satisfactory

In addition to quoting from the study in Nature and an editorial published alongside it, the article includes an independent expert who provides a measured and objective assessment of the finding which helps put the study in better context. While stating that the research is “a cool observation,” he added that “this is not a biomarker yet” since the study was too small to draw a conclusion.

Does the story compare the new approach with existing alternatives?

Not Satisfactory

The story doesn’t mention how pancreatic cancer is currently diagnosed. Tests to identify pancreatic cancer in patients include, but aren’t limited to, physical exams to look for the presence of jaundice, blood tests, imaging tests and biopsy.

Does the story establish the availability of the treatment/test/product/procedure?

Satisfactory

The article gives no indication when the discovery could be translated into a clinical screening tool but reviewers don’t see that as a drawback in this story. The article is cautious about the implications of the finding and  highlights experts calling for additional research so we can assume the tool is some years off.

Does the story establish the true novelty of the approach?

Satisfactory

The story establishes what is novel about the test — the fact that it has the potential to detect cancer at an early, more treatable stage. The story could have done more to establish whether there has been other research into tests for pancreatic cancer and how the new test builds upon those previous efforts.

Does the story appear to rely solely or largely on a news release?

Satisfactory

The story includes comments obtained from an interview with an independent expert, and statements from a published editorial about the significance of the research.

Total Score: 5 of 10 Satisfactory

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