Le Monde tends to be pretty rigourous I would say; it is here again. You've cut or missed the references and/or quote attributed to Professeur David Khayat, from the Institut du cancer and numbers from l'Institut de veille sanitaire, both of which look serious enough bodies to me with the relevant expertise/numbers to pass comments. Le Monde supports its statements. The rest is for the most part relating what riders have admitted to themselves.
Anquetil's condition has often been linked to his "past", so what is related here is not news really; not to his legendary diet of champagne and pheasant (only)!