Three cancers that should never be poked (biopsied)Health experts have cautioned that biopsy may carry risks in certain suspected cancers, potentially spreading malignant cells. In biopsies, a small piece of the malignancy is collected and then tested in the laboratory for cancer cells. Dr Priyam pointed out that testicular cancer should not be biopsied. The second tumour that should never be poked is Wilms Tumor (Kidney Cancer in Children), Dr Priyam said. As a result, it instantly transforms a localized, highly curable case into one that suddenly demands chemotherapy,” Dr Priyam said.