Introduction – World Cancer Day will be celebrated every year on February 4 across the world to spread awareness about cancer and promote its treatment, detection, and prevention It is mainly observed by the (UICC) Union for International Cancer Control to support the goals of the World Cancer Declaration, which was written in the year 2018. The main purpose of this international day is to reduce deaths that are caused by cancer. This international day was celebrated by the United Nations and targets misinformation decreases stigma and raises awareness.

At present, cancer is the second leading cause of death and millions of people die due to cancer worldwide. Several types of cancer that occur but the most common cancers which affect mostly in India are cervical, colorectal, lung, neck, brain, and breast cancer. Now, cancer has become a major health concern in the past several years across the world.

Cancer – It is the uncontrolled growth of abnormal cells anywhere in a body and can occur in any organ and at any age. In this dangerous disease, the damaged cells grow, divide, and spread abnormally. If it is not treated on time, it can become fatal.  Cancer works in different stages. In stage zero, there is no harm, as cancerous cells do not perform any activity. In the stags first, second, and third, their speed of infecting other organs increases and this can lead to death. Symptoms of the disease sometimes can be diagnosed due to the formation of tumors.

But there are many situations in which symptoms are shown at a later stage. Cancerous basically occurs when there are changes in genetic code, which makes certain types of cells cancerous. The growth of these cells in other parts of the body damages other organs and this can lead to various types of problems. Millions of people in the world die of cancer if it is not treated timely. The treatment of the disease becomes costly and it depends on the stage in which the disease has reached.

Several types of cancer – There are several types of cancer, which are discussed below –

1. Blood Cancer – This type of cancer occurs when abnormal blood cells start growing out of control that interrupts the function of normal blood cells which helps in fight against infection and produce new blood cells. Most of the blood cancers start in the bone marrow where blood cancer is produced is also known as hematologic cancers.
2. Cervical cancer – It is the fourth most common cancer among women across the world and is caused by persistent infection with the human papillomavirus (HPV). Women are suffering from HIV (Human immunodeficiency Viruses) may be 6 times more likely to develop cervical cancer as compared with women without HIV. HPV is a common infection which passed or spread through making sexual relationships and is the main cause of cervical cancer.
3. Breast cancer – It is one of the most common cancers especially in women that occurs in the cells of the breast. The breast is the important part of the body that is made up of three parts such as lobules, connecting tissues, and ducts. The lobules are the main part of the breast that produce milk for the baby and ducts are tubes that carry milk to the nipple. In the breast, the connecting tissue is made up of fatty and fibrous tissue which surrounds and holds everything together. Most of the cases of breast cancer start in the lobules or ducts. It can spread outside the breast through lymph and blood vessels. This type of cancer may occur in both men and women but it is most common in women.
4. Bone Cancer – It is one of the rare cancers that occurs when a tumor or abnormal mass of tissue forms in a bone. A tumor may be cancerous which means it is growing aggressively and spreading to other parts of our body.  Bone cancer affects the pelvis or the long bones in the arms and legs.
5. Brain Tumor– It is a dangerous disease, which occurs when cells grow at an abnormal rate to form a mass of abnormal cells inside the brain. A brain tumor can occur in the brain tissue and may be a life-threatening disease for people however it can be treatable completely. If a brain tumor occurs inside the brain and is known as a primary brain tumor and sometimes, cancer may spread to the brain from several other parts or organs of the human body and is called as metastatic brain tumor. A brain tumor is divided into two types such as benign (non-cancerous) tumors and cancerous (malignant) tumors. The treatment of a brain tumor depends on the type, size, location of the tumor in the human body.
6. Neuroendocrine Tumor or Cancer – It is that type of cancer that spreads in specialized cells and are known as neuroendocrine cells. The work of neuroendocrine cells is to send and receive messages via hormones to help the body function. Neuroendocrine tumors are one of the rare cancers that may occur anywhere in the body. This type of cancer mainly occurs in the appendix, pancreas, rectum, lungs, and small intestine. There are several types of neuroendocrine tumors, some grow gradually, and many very fast. Several neuroendocrine tumors may produce excess hormones (functional neuroendocrine tumors) and many others do not release hormones or also do not release sufficient to cause symptoms (non-functional neuroendocrine tumors).
7. Lung Cancer – It is a type of cancer that begins in the lungs and is one of the leading causes of cancer deaths all around the world. Smokers have a high risk of lung cancer as compared with non-smokers. The risk of lung cancer increases in people with the number of cigarettes and length of time smoked. If you quit smoking after several years then you can lower the possibility of developing lung cancer.
8. Bladder Cancer – This type of cancer occurs in the tissues of the bladder that is the organ in the body, which holds urine.  It is one of the common types of cancers, which begins in the cells of the bladder. The bladder is a hollow muscular organ and is placed in the lower abdomen, which stores urine. This type of cancer may occur in the urothelial cells, which line the inside of the bladder. Urothelial cells are present in the kidneys and the tubes (ureters), which connect the kidney to the bladder. Most of the cases of bladder cancers are diagnosed in an early stage when the cancer is highly treatable
9. Pancreatic Cancer – This type of cancer develops when an uncontrolled growth of cells begins in a part of the pancreas. The pancreas is situated behind the stomach near the gallbladder and in the back of the abdomen. It has glands that produce hormones including enzymes and insulin.

There are several other types of cancer are stomach cancer, colorectal cancer, skin cancer, thyroid cancer, kidney cancer, penile cancer, thyroid cancer, and many more.