In today’s world, Cancer is one of the major and the most serious problems across the globe. But the fear of cancer is more dangerous than the cancer itself. The human body is made up of cells. These cells are the basic functional and structural units of the body. We all have been taught in our biology classes in the school days that how an animal cell is. These cells form tissues. Thus, cells are collectively tissues. Tissues together form an organ, say Liver, Stomach etc.
An organ, along with other organs makes a system. Like our digestive system consists of Stomach, Gall Bladder, Intestines etc. Normally, these cells, tissues, organs and every system work in a controlled and managed manner. This normal functioning of each cell of the body maintains the health and life goes normally. These cells have a limited life span. They are made, they work and they die. The dead cells are then replaced by new cells and the cycle goes on. Cells follow all the rules of life process and multiply by a normal process of cell division which is a controlled process and then the cells grow and function.
But sometimes, this controlled process gets uncontrolled and the cell division triggers off. The cancer cells develop from normal cells when the DNA of the normal cells gets damaged and the cells are transformed. Cancer is the uncontrolled cell division and cell growth of abnormal cells in parts of body which result in extra growth of the abnormal cells, forming a tumor. A tumor is the mass of uncontrolled abnormal cells.Cancer is medically known as Neoplasm which means new growth if it is harmful. Some are harmful and some are not. So, it can be grossly classified into harmful cancers and harmless tumors. One thing has to be noted that one can call a tumor as cancerous if it is malignant (harmful). But those which are benign cannot be called cancerous. They should be termed as tumors or growths only.
Malignant Tumors are the harmful cancers. They are characterized by severe destruction, spread, and invasion.
Destruction – The abnormal cancerous mass rapidly grows and starts involving the normal parts of rest of the organ. This is the destruction of the normal part by the cancerous growth. The new growth may resemble the cells from which it grew or it may even appear in a different type. The tumor cells which closely resemble the remaining normal cells are called as well differentiated tumor. In normal conditions, all the cells of a healthy organ are differentiated and they look the same in any part of that organ. Differentiated tumors which closely resemble the healthy cells have a better future. Tumors which totally change up and do not resemble the original healthy cells are called as poorly or undifferentiated tumors. They are more severe than the differentiated ones.
Spread – These malignant tumors are dangerous as the can spread easily as they grow. They spread through various means and get deposited in various body parts and then grow there independently as secondary tumors. Suppose there is a tumor in the breast of a female. The tumor grows and gets bigger and then a part of it gets detached, spreads through various means and reaches some other part of the body. There it starts growing as it gets nutrition and becomes the secondary center for growth. The tumor may even spread further to other parts but it is rare as in many cases by that time, the patient becomes so ill that the life terminates. Modes of spread – The tumor can spread either directly or by lymphatic fluid or by blood.
Direct Spread – The tumor directly spreads to the nearby organs from its primary site. As the tumor grows, it occupies more and more space. As soon as it comes in contact with other organ directly it leads to the spread to the adjoining organ which came in contact of the tumor. Suppose there is a malignant tumor in the breast. It soon spreads to the lungs which lie behind and arm pits (axilla). So the tumor parts spread and start growing in these adjacent organs. This is the direct local spread.
Blood Spread – It is the hematogenous spread of the cancer cells from one part to another part, that is from the primary center to the secondary center. As the tumor grows, it spreads in size and reaches the nearby blood vessels. It then starts invading and penetrating the vessels and thus a part of the tumor gets separated and enters the blood circulation. This piece of tumor, circulating in the blood system is known as malignant embolus. Now the blood transports the tumor piece and thus it gets implanted where the blood takes it. This can be anywhere in the body and the tumor grows at that site as a secondary growth.
Lymphatic Spread – Lymphatic system of the body consists of Lymphatic organs, Lymph nodes and Lymph vessels. Lymphatic system is an open circulatory system which contains a clear fluid called Lymph. The primary cellular component of the Lymph is Lymphocytes. These are the protective cells of the body which provide immunity. Except for immunity, Lymph also has other functions like transportation, excretion etc.
The tumor, as it grows, invades the Lymphatic vessels and thus gets transported to different body parts of the body and grows as secondary tumors.
This way the malignant tumor spreads and grows its kingdom and thus it becomes harmful. This spreading of malignant tumor is called Metastasis. They have this tendency to survive and conquer new territories.
Invasion – By invasion, the tumor becomes harmful as it invades into the organ where it started growing. This invasion locks the tumor into the organ and thus making it fixed into the organ making it difficult for the surgeons to cut it out completely and properly. The tumor invades deeply and thereby making the conditions worse. Example- Just like it is very easy to just lift the plant which is kept in a pot than to remove a plant which is growing in the garden as the roots of that plant has invaded itself into the soil which makes it difficult to remove.
So, a malignant tumor invades, spreads and causes destruction of the body parts and thereby, it is fatal for the host (patient). It grows so rapidly that the body and the immune system is not able to match up the speed and thus growth becomes more than the destruction of the tumor by the immune system. A tumor grows like the normal cells only but the speed of growth is fast and the cells of the tumor do no obey the basic rules. They also need nutrition and blood for survival and thus a cancer patient starts becoming weak as most of the energy gets consumed by the tumor if it is malignant and is growing fast. Also one can see that such fast growing tumors sometimes remain deficient of blood supply in the central part where the blood vessels could not reach properly due to the rapidity of growth. Thus the central part starts becoming dead and the central tissues undergo decay. This is called central necrosis of the tumor. Necrosis, in general, is the death of a cell/tissue which can happen anywhere in the body in different conditions. These malignant tumors do not have any covering, thus they freely spread.
Benign Tumor – A benign tumor is generally harmless. Even though they are also from the same group of uncontrolled growth of cells, they are much different from the malignant variety. They grow but they do not spread or invade.
A benign tumor is well capsulated. It has a thick covering made up of fibrous connective tissue which keeps the tumor cells inside. With this reason, the benign harmless tumor does not spread to different parts of body which means there is no metastasis in cases of benign cells. These tumors do not invade the surrounding structures too. They are mostly circular or oval and they just grow in size and do not mix up with other structures. This makes it simple for the surgeons to cut and take it out.
A benign tumor grows in size and thus when left untreated or when it grows too large, it starts compressing the surrounding structures and may cause secondary problems. Sometimes it displaces the surrounding structures too. Thus it can damage a nerve or compress a blood vessel and reduce blood supply to an organ. This is known as the mass effect of the tumor. It remains confined to its own place. There is no threat to life until the tumor presses upon the vital structures and causes problems. As they are not harmful thus they are called non-cancerous tumors. They grow at a slower rate than that of the malignant ones.
Cells of a benign tumor are well differentiated (the cells resemble the cells from which they originated and thus more normal functionality is there). Sometimes when a benign tumor arises from an endocrine gland (hormone secreting tissue), and when it is well differentiated then the tumor also starts producing that hormone and there is an excessive hormonal production leading to imbalance in the levels of that hormone.
Sometimes, there may be a transformation of a benign tumor into a malignant one. That is from being harmless to harmful. This is known as tumor progression.
So basically, the difference between a benign and a malignant tumor is the ability to invade the surrounding structures. A tumor which does not invade into the nearby structures and remains in that local area only then it is said to be benign. If invasion is there, it belongs to the malignant category.
Signs and Symptoms of cancer in general: The signs and symptoms depend upon the location of the tumor in the body. Many of the malignant growths present themselves as ulcerations. (Ulceration is the formation of ulcers which are formed by breaking of the surface and creating a wound). Many growths take up a cauliflower type form and grow in that manner. Sometimes the growth may compress body tracts or may occlude the tracts and cause obstruction, resulting in the related symptoms.
Most harmful effects by the malignant tumors are caused due to their local effects on the neighboring structures. They invade and destroy the surrounding structures. Although they follow the path where they get least resistance against invadation. They infiltrate and destroy the walls of blood vessels, lymphatic vessels, nerves, muscles and bones. They invade, encircle and obstruct the tube like structures of the respiratory, gastro intestinal system, genito-urinary tracts and their associated structures. They ulcerate and destroy the mucous membrane (organ lining and inner lining of structures) and skin. Initial symptoms may not help in diagnosis of the case but one must always pay attention when our body speaks.
A proper history and physical examinations may suspect for a tumor which has to be confirmed by radiological tests and laboratory tests.
Condition of the patient due to Cancer – The patient having the cancerous tumor is called the host. Benign tumors do not cause any problem as such in the patient’s condition. But when it comes to malignant cancerous tumors, it greatly affects the condition of the patient. Tumors affect the host by their metabolic activities. Just like the normal cells, tumor cells also show metabolism, although in an altered state. When the tumor becomes too large then it starts affecting the body metabolism process. This is due to the diversion of nutrients to the tumor cells than to the normal cells. This results in weakness of the patient, slow emaciation (losing out the body flesh). Also there may be a bad effect on the body due to the release of intoxicated products released by the metabolic process in the tumor cells. This way, the person has to face the illness on one side and undernourishment on the other side. Example – We can think of the patient as the burning candle. But here the candle burns from both the ends, resulting in a rapid destruction and death. One side of the candle is burnt by the harmful tumor and on the other side, the poor nutrition supply affects the patient’s condition.