A tumour is a 'lump' or 'growth' of tissue made up from abnormal cells. Tumor is not synonymous with cancer. Both tumor and cancers are different. Tumors are divided into two types - benign and malignant.
While there is no need to be afraid of any of the thousands of diseases you could get, it pays to be sensible. None of us like to feel like hypochondriacs, it is only sensible to keep your self informed on common and new diseases