My mother have had 3 types of cancer (that is: of separate types not related to each other) and been cured of them all using different kinds of treatments.
My father have a friend that had bone cancer in the cheek which was successfully removed surgically with chemo therapy afterwards to avoid spreading.
A relative was diagnosed with throat cancer (she was a life-long smoker) and the first treatment planned was an operation to remove the main tumors, after opening her up it was discovered that the cancer had spread more than expected and later examinations showed the tumors had spread throughout most internal organs. Then the care shifted to make her death as comfortable as possible.
I could list more examples but the fact is that oncologists are medical doctors just as any in the field and yes they are treated by the same methods as anybody else if they get cancer. This strange paranoid fixation on oncologists is strangely often linked to antisemitism for some reason, like all oncologists would be Jews...