After two years of pandemic, the high mass of the European Society of Medical Oncology (ESMO) found a face-to-face edition, like its American counterpart, ASCO, in June. From September 9 to 13, more than 23,000 oncologists, researchers and industrialists gathered in Paris around the latest advances in science and cancer treatment. “There was a joy to meet again, it was palpable”testifies Professor Caroline Robert, head of the dermatology department at Gustave-Roussy (IGR), in Villejuif (Val-de-Marne).
What to remember from this abundance of novelties, when hundreds of speakers have followed one another? A breakthrough, perhaps, which concerns certain cancers of the colon or rectum, the third tumors in frequency in France. It could, in fact, change the situation, in the long term, for the patients concerned, by sparing them from mutilating surgeries. A hope to be confirmed, because it is still a study conducted on a small number of patients, 112 in total.
However, when Myriam Chalabi, of the Netherlands Cancer Institute in Amsterdam, unveiled these first results in the large auditorium of the congress on Sunday, September 11, the room applauded without even waiting for the end of the presentation, thus departing from custom.
95% regression of tumors
You should first know that the standard treatment for patients with non-metastatic colon cancer is surgery, followed or not by chemotherapy, depending on the case. But, here, the patients were first treated for four weeks with a series of immunotherapies, then they were operated on one to two weeks later. Examination of the surgical specimens reveals that a total of 95% of the tumors regressed by 90%, and 99% by more than 50%. By comparison, when this type of patient receives conventional chemotherapy before surgery, only 5% to 7% of tumors regress by more than 50%.
However, this advance only concerns a fraction – 10% to 15% – of non-metastatic colon cancers. These are tumors that present specific genome abnormalities, called “microsatellite instability”. They result from a failure of the DNA repair system (dMMR), during its duplication. A third of these abnormalities are linked to a hereditary disease, Lynch syndrome, known to increase the risk of cancers of the colon, uterus and ovaries.
“This treatment could concern several hundred patients per year, even counting only localized cancers linked to a failure of the DNA repair system. Colorectal cancer, in fact, is very common, with 43,000 new cases per year in France.explains Pauline Vaflard, medical oncologist at the Institut Curie (Paris).
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