Preventing the big killer, a new study may change the rules of screening

The implementation of prevention programmes is crucial to diverting this disease trajectory. And in this respect, therefore, all screening tests work. But to varying degrees.

by Maria Rita Montebelli

29 April 2026

4' min read

Translated by AI

Versione italiana

Key points

The test challenge: which one prevents better (and costs less)
The test challenge: who prevents better (and costs less)
A practice changing strategy: less invasive, more cost-effective
Rise in colon cancer cases at a younger age

4' min read

Translated by AI

Versione italiana

It has always been one of the big killers par excellence. Indeed, colorectal cancer is one of the most widespread and deadly cancers in the world (it is the second leading cause of cancer death globally). But it is also one of the most preventable. This neoplasm, like the others, in fact grows slowly, often over several years, from benign lesions (polyps) that can be detected and removed before they become dangerous. The decisive variable for success is therefore not so much how to 'cure' it, but how to get there in time.

And it is on this terrain that the vital game of screening is played. In Italia, screening for colorectal cancer is offered free of charge by the National Health Service (SSN) to all citizens between 50 and 69 years of age (in some regions it has been extended to 74 years of age) and involves the detection of faecal occult blood (Sof) every two years. In the event of a positive result, an in-depth colonoscopy is proposed. But this strategy could be enriched with new instruments in the future.

The test challenge: which one prevents better (and costs less)

A study published in the journal Radiology (official organ of the RSNA, the Society of American Radiologists) compared two diagnostic strategies: virtual colonoscopy, which uses CT scans to reconstruct the inside of the colon, and faecal DNA testing, which analyses faecal samples for molecular markers associated with cancer. To compare the results of these two approaches, the researchers built a sophisticated mathematical model (Markov model), which simulates the evolution of the disease over time. For this work, they 'imagined' a population of 10,000 healthy people, representative of the US population aged 45 (the age at which many guidelines now recommend earlier screening, in light of the increase in cases of colorectal cancer among younger people) and followed them virtually until the age of 75, assuming perfect adherence to screening.

Three screening strategies have been modelled on this 'population': faecal DNA testing every 3 years, the virtual colonoscopy (CTC) strategy with immediate polypectomy (conventional CTC) for all polyps 6 mm or larger every 5 years, and the surveillance strategy (CTC surveillance) involving follow-up with virtual colonoscopy every 3 years for small polyps (6-9 mm) and polypectomy for large polyps (≥10 mm).

The necessary premise is that, in the absence of screening, approximately 7.5% of these people would develop colorectal cancer. Only the implementation of prevention programmes is able to divert this disease trajectory. And from this point of view, therefore, all screening tests work. But to varying degrees. Faecal DNA testing reduces the incidence of colon cancer by 59%. Virtual colonoscopy does better, leading to a 70% risk reduction with the surveillance CTC strategy and 75% with the conventional CTC strategy. Percentages that translated into everyday clinical reality mean hundreds of cases of colon cancer avoided in a relatively small population (the 10,000 virtual patients in this study).

The test challenge: who prevents better (and costs less)

And it is not just a question of different effectiveness. The most interesting fact concerns the economic impact. Because obviously the issue of sustainability, especially in public health systems, is an inescapable component of prevention. To measure this, the authors of the study used a standard indicator, the QALY (quality-adjusted life year), which combines quantity and quality of life gained as a result of a healthcare intervention. The faecal DNA test is confirmed to be 'cost-effective', at a cost of about $9,000 per healthy life year gained. A positive result certainly, but far below the commonly accepted thresholds. Quite different is the case with virtual colonoscopy, which does much better: not only is it more effective, it is even 'cost-saving'. In other words, it saves resources compared to no screening and is therefore clinically and economically superior to faecal DNA testing. A result that overturns the mainstream assumption that more advanced technologies automatically lead to higher costs.

A practice changing strategy: less invasive, more cost-effective

Another important point for reflection emerges from this study. It is not necessary, indeed not convenient, to intervene on every small polyp detected. It is the largest lesions, those over 10 millimetres, that are the real target of prevention, because they are the ones most likely to develop into cancer. Hence the idea of a hybrid strategy that envisages the use of virtual colonoscopy to monitor the smallest polyps over time, with checks every three years, while reserving traditional colonoscopy only for cases with the largest or most suspicious lesions. It should be pointed out that, although slightly more effective, conventional CTC, leading to more optical colonoscopies, has a disadvantage in terms of cost-effectiveness compared to the CTC surveillance strategy.

The one proposed by this study is therefore a different logic, a more selective risk stratification, which avoids embarking on unnecessary invasive procedures and reduces NHS costs, without compromising effectiveness. And it is precisely this combination (CTC surveillance) that presents the best compromise between clinical benefit and economic sustainability. In contrast, a more aggressive and interventional approach, which consists of referring all patients with polyps larger than 6 millimetres to colonoscopy, proves less cost-effective according to the results of this study, because the additional costs are not compensated for by a real health gain.

Colon cancer cases are increasing at a younger age

Meanwhile, the epidemiological context is also evolving. The increase in colon cancer cases among younger people has already prompted several scientific societies and the U.S. Preventive Services Task Force to lower the age for starting screening to 45. And although traditional colonoscopy remains the most popular diagnostic investigation, especially in the United States, there is growing interest in less invasive and more accessible alternatives, such as faecal DNA testing and virtual colonoscopy, both of which are already reimbursed by Medicare.

According to Perry J. Pickhardt, first author of the study, the point is this: among the most reliable and minimally invasive diagnostic options, virtual colonoscopy is not only the most effective in detecting and preventing cancer, it is also the most cost-effective. And with a further added value: the possibility of intercepting, during the same examination, signs of other diseases, such as osteoporosis or cardiovascular diseases.

The implementation of virtual colonoscopy, in short, would, according to American researchers, optimise the time available before a tumour develops. And the take-home message of this sophisticated and number-filled study is quite simple: colorectal cancer can be successfully prevented. But to do so, it is not enough to rely on just any test. You need to do the right one, at the right time.