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What is the early clinical diagnosis ?

Study's summary and key findings

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See also the page of the site Cancer Rose on the same subject

Version françaiseEarly clinical diagnosis as effective as screening

The Lancet Oncology has published a study suggesting that early clinical diagnosis may be as effective as screening in avoiding advanced cancers and reducing breast cancer mortality.

What is the early clinical diagnosis ?

To begin, it is necessary to define the early clinical diagnosis of breast cancer.
Early clinical diagnosis refers to the prompt recognition of the first symptoms of breast cancer to diagnose and treat it without delay.
These early symptoms may be : palpation of a lump inside the breast, discharge from the nipple, a change in the appearance of the skin on the breast, or a deformed breast.

Screening and early clinical diagnosis should not be confused.
Screening is intended for women who have no symptoms, as it aims to detect cancers before they cause symptoms. That is why screening can result in so much overdiagnosis: the earlier we try to find tumors, the greater the risk that the tumor will not progress as expected, leading to fatal cancer if left untreated.
Early clinical diagnosis is intended for women who have symptoms that could lead to the suspicion of breast cancer. It is, therefore, less ambitious than screening in terms of early diagnosis but does not carry the risk of overdiagnosis since the tumor has already started to show symptoms.

The study's summary and key findings

The goals of this extensive study were twofold :
- to compare breast cancer mortality and a broad panel of public health indicators to determine which of these indicators is critical for breast cancer mortality,
- to investigate the relationship between breast cancer mortality and the proportion of cancers in the early stages (stage I or II).
All countries with available data were included (141 countries for the mortality/public health indicators analysis and 35 countries for the mortality/proportion of early stages study).

Among the results of the study, we note that :

Another study that did not find a decrease in mortality with screening

This study adds to the long list of observational studies that have found no reduction in mortality with screening.
Of course, observational studies are not as reliable as randomized controlled trials, and their conclusions should be taken with caution. However, if, as we are told, screening results in a 20% reduction in breast cancer mortality, why is it so difficult to find a correlation between screening and breast cancer mortality ?

Screening or early clinical diagnosis ?

The authors emphasize the importance of early detection of breast cancer, but they make it clear that early detection is not limited to screening.
Screening is only one of two methods of early detection, and there is another method that also allows for early detection of breast cancer : early clinical diagnosis.

In its « Guide to cancer early diagnosis », the WHO validates this alternative to screening and recommends it for countries that do not have the resources to implement mass screening.
The study results, published in The Lancet Oncology, confirm the WHO recommendation, suggesting that early clinical diagnosis may be as effective as screening in avoiding advanced cancers and reducing breast cancer mortality.

Therefore, why not replace screening with an early clinical diagnosis ?
Of course, one could object that the WHO recommendation concerns countries that do not have the means to implement screening, which is not the case in France. In countries that can afford to screen, it might seem unreasonable to replace screening with early clinical diagnosis, which is at best as effective but certainly not more effective than screening.
This objection is only valid if only effectiveness is taken into account. Suppose we reason from a benefit/risk perspective, considering both effectiveness and risks. In that case, the choice of early clinical diagnosis becomes reasonable. Compared with screening, early clinical diagnosis may be slightly less effective in avoiding advanced forms of breast cancer and reducing mortality from breast cancer. Still, it does not lead to overdiagnosis and considerably reduces overtreatment.

Meanwhile, women should know that not participating in screening does not mean they will die of breast cancer. By doing self-examination and by being concerned without delay about any abnormality in their breasts (swelling, discharge from the nipple, skin changes, etc.), the diagnosis of possible cancer can be made early enough that the prognosis remains almost as good as if they had been screened. And this preserved prognosis will be obtained without overdiagnosis and with much less risk of overtreatment.

Duggan C., Trapani D., Ilbawi A., Fidarova E., Laversanne M., Curigliano G. et al.
National health system characteristics, breast cancer stage at diagnosis, and breast cancer mortality: a population-based analysis
DOI:https://doi.org/10.1016/S1470-2045(21)00462-9
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Dernière mise à jour le 05/11/2021