Do plants get cancer? The answer is, ‘Yes’, if cancer is defined as dysregulated cell growth, but typically plant cancer is different than in animals. Plant cells have a rigid cell wall that limits metastatic spreading of cancer cells through the plant. Instead, the tumor grows as a single mass called a gall. Also, most plant tumors/galls are caused by a viral infection that disrupts the normal expression of genes. Here is an example that I found in my garden. I think this is an onion bulb where the new shoot has developed as a tumor of abnormal stem/leaf cells.
Plant Tumor

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