Ovarian cancer is rare but particularly fatal. Scientists are divided, a new study discusses the value of screening to reduce mortality.
Ovarian cancer is one of the rarest in France, affecting just over 3,000 women each year. However, it is a particularly aggressive cancer, with mortality five years after diagnosis exceeding 60%.
This gloomy prognosis can be explained in part because ovarian cancer is often detected late, when the disease is already well advanced. It must be said that the merits of screening and the relevance of the detection tools currently available to experts are still debated.
A large study,published this Thursday in the scientific journal The Lancet, is interested precisely in this issue of screening. With more than 200,000 participants, followed over a maximum period of 14 years, this work is among the most ambitious ever carried out on the subject.
The researchers wanted to determine the impact of current screening tests on mortality. Their results were eagerly awaited, but still failed to get all the experts to agree. Some are not convinced of the relevance of current screening methods.
The challenge of screening
The most widely used test, and evaluated in the Lancet study, is to measure the concentration of CA125, a protein, present in the blood serum of women. Problem: this biological marker is not specific to cancer, and may be a sign of another benign pathology of the ovary.
The “normal” concentration threshold is evaluated at 35 IU / L, but several studies have shown that it is more interesting to regularly assess the variations in the CA125 concentration of each woman, rather than looking for precise thresholds.
“The CA125 serum is a diagnostic aid, it allows better guidance of patients. In general, for ovarian pathologies, it is interesting, but still insufficient, ”explains Prof. Patrice Mathevet, head of the gynecology department at Lausanne University Hospital.
In the event of a concentration considered abnormal, an endovaginal ultrasound is offered to the patients, in order to detect the abnormalities. This can also be offered as a first-line treatment, but this method leads to a significant number of “false positive” results.
More than 200,000 women
In the Lancet study, researchers conclude that these screening techniques, despite their apparent flaws, can help reduce mortality. In all, 202,638 women aged 50 to 74 were followed.
They were divided into three groups. In the first, the participants were not screened, in the second, they were tested only by ultrasound, and in the last, by a serum CA125 test, then by ultrasound in second line.
In the first case, 630 cancers were diagnosed during follow-up, 338 in the second and 314 in the third. Excluding women who already had undiagnosed ovarian cancer at the start of the study, the scientists estimate that screening combining CA125 and ultrasound resulted in an average 20% drop in mortality during follow-up.
“20% that might sound like a lot. But this decrease in mortality is in fact not huge when we talk about a group that has benefited from all the screening techniques available. Above all, it does not necessarily compensate for the side effects of screening, which can be deleterious, ”emphasizes Professor Mathevet.
According to the practitioner, these results show a favorable trend, but they will not lead to a systematic implementation of screening, because the reduction in mortality is not significant enough at the population level.
Low cost effective
Behind this study actually hides the issue of whether screening is cost effective. Prof. Mathevet explains that beyond the economic cost, the tests can sometimes cause more harm than good, insofar as false positives can give rise to surgical procedures that leave after-effects.
Another problem is the diversity of cancers. “Finding an effective screening tool is complicated, because of the great diversity of ovarian cancers. Often the cancer is very aggressive and grows very quickly, so it would have been difficult to find it in time anyway. If it is only mildly aggressive, screening early only represents a small gain in setting up the appropriate therapeutic arsenal, ”explains Professor Mathevet.
Unless a more relevant screening tool is found, systematizing these tests is therefore not of major interest to him.
Even for women carrying the BRC1 and BRC2 genes, who are more at risk of developing this cancer, practitioners may prefer prevention to screening, deeming these tools too unreliable. They offer in particular rather an ablation of the ovaries, as in the highly publicized case of actress Angeline Jolie.
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