Cancer is defined as disease that describes uncontrolled cell growth which means these cells are characterised by unregulated division. Thus, it forms group of cells which is called as tumor.
There are two different types of tumors which are benign tumors and malignant tumors.
Benign tumor is surrounded by a fibrous capsule which is made up of connective tissue. It normally resembles normal cells and does not invade adjacent tissue. Now question arises, why benign tumor does not invade adjacent tissue? Answer to this is because of presence of fibrous capsule.
People having benign tumors sometimes is harmless such as a mole is a benign tumor of skin cells which is called as melanocytes. But all benign tumors are not harmless. If the tumors restrict a normal tissue’s blood supply then it is harmful and affects the function of normal tissue.
Malignant tumor cells do not resemble normal cells and invade adjacent tissues and thus come in contact with either blood or lymph vessels that allows tumor to spread throughout the body. Therefore, malignant tumour is dangerous.