Cancer

It is a condition where certain cells in the body begin to grow uncontrollably and can spread to other areas. It can originate in almost any part of the body. Under normal circumstances, cells grow, divide, and create new cells as needed. When old or damaged cells die, they are replaced by new ones. However, in cancer, this process malfunctions, leading to the rapid growth of abnormal cells.

1.0Introduction

• Cancerous tumors invade nearby tissues and can spread to distant parts of the body to form new tumors, a process known as metastasis. These tumors are referred to as malignant. Many cancers develop as solid tumors, though blood cancers like leukemia typically do not. 
• In contrast, benign tumors do not invade surrounding tissues or spread. Once removed, they typically don't return, unlike malignant tumors. However, benign tumors can grow large and, in some cases—like those in the brain—can cause severe symptoms or become life-threatening.

2.0Differences Between Cancer Cells and Normal Cells

Cancer cells differ from normal cells in many ways. For instance, cancer cells:

• They grow without receiving signals that usually trigger cell growth, unlike normal cells that rely on such cues.
• They ignore signals that instruct cells to stop dividing or undergo apoptosis (programmed cell death).
• They invade nearby tissues and spread to other parts of the body, whereas normal cells stop growing when they come into contact with other cells and typically stay in place.
• Cancer cells attract blood vessels to tumors, providing them with oxygen and nutrients while removing waste.
• They evade the immune system, which normally eliminates damaged or abnormal cells.
• Cancer cells often accumulate changes in their chromosomes, such as duplications or deletions, and may have twice the usual number of chromosomes.

3.0How Does Cancer Develop?

• Cancer arises due to changes in genes, which are the basic units of inheritance located on chromosomes made of tightly packed DNA. 
• These genetic changes affect how cells function, particularly in terms of growth and division. Cancer-causing gene mutations can occur for two main reasons:
• They may be inherited from our parents.
• Over time, the body's ability to remove cells with damaged DNA weakens, increasing the risk of cancer as we age. 
• This decline in DNA repair is a key factor in the higher cancer risk in later life.

4.0Types of Genes that Cause Cancer

• Genetic changes contributing to cancer typically affect three main types of genes—proto-oncogenes, tumor suppressor genes, and DNA repair genes. These alterations, often referred to as "drivers" of cancer, can lead to uncontrolled cell growth:
• Proto-oncogenes regulate normal cell growth and division. When mutated or overly active, they become oncogenes, causing cells to grow uncontrollably.
• Tumor suppressor genes control cell division. Mutations in these genes can result in unchecked cell proliferation.
• DNA repair genes fix damaged DNA. Mutations in these genes lead to additional genetic errors, which can transform cells into cancerous ones.
• When cancer cells spread from their original location to form new tumors elsewhere, this is called metastasis. A cancer that has spread is known as metastatic cancer.

5.0Types of Cancer

• There are numerous types of cancer, typically named after the organ or tissue where they originate. 
• For instance, lung cancer begins in the lungs, while brain cancer starts in the brain. Additionally, cancers can be classified by the type of cell from which they develop, such as epithelial cells or squamous cells.

1. Carcinoma :

These are the most prevalent type of cancer, arising from epithelial cells that line both the internal and external surfaces of the body.

2. Sarcoma :

Sarcomas are cancers that develop in bone and soft tissues, including muscles, fat, blood vessels, lymph vessels, and fibrous tissues such as tendons and ligaments.

3. Leukemia :

• Leukemias are cancers originating in the bone marrow's blood-forming tissues. 
• Unlike most cancers, they do not form solid tumors. 
• Instead, they lead to the accumulation of abnormal white blood cells (leukemia cells and leukemic blast cells) in the blood and bone marrow, which overcrowds and suppresses normal blood cells.

6.0Example of some cancer

Bone Tumor:

• A mass of unusual cells growing in a bone. Causes of bone tumours include abnormal healing of an injury, inherited conditions and radiation therapy. They can also be caused by bone cancer or another cancer that has spread to the bone from other parts of the body.
• A bone tumor may be painful also. Some people have dull, aching pain. In some cases, a minor injury causes a fracture near the tumour.
• Treatments include surgery and radiation.

Colon Cancer:

• It is a type of cancer that develops in the colon, located at the lower end of the digestive tract. In its early stages, it often begins as non-cancerous polyps, which usually do not present symptoms but can be detected through screening. 
• The symptoms of colorectal cancer can vary depending on the size and location of the tumor and may include changes in bowel habits, alterations in stool consistency, blood in the stool, and abdominal discomfort. 
• Treatment options are influenced by the cancer's size, location, and extent of spread, with common methods including surgery to remove the cancer, as well as chemotherapy and radiation therapy.

Gallbladder Cancer:

• Gallbladder cancer originates in the gallbladder, an organ whose size and position can allow the cancer to progress unnoticed. 
• Often, there are no symptoms, but when they do occur, they may include abdominal pain, bloating, and fever. 
• Treatment options typically involve surgery, chemotherapy, and radiation therapy.

Lung Cancer:

• Lung cancer originates in the lungs and is mainly classified into two types: non-small cell lung cancer and small cell lung cancer. 
• Key risk factors include smoking, exposure to second-hand smoke, certain environmental toxins, and family history. Symptoms often manifest only in the advanced stages and may include a persistent cough (sometimes with blood), chest pain, wheezing, and weight loss. 
• Treatment options can vary and may involve surgery, chemotherapy, radiation therapy, targeted drug therapy, and immunotherapy.

Breast Cancer:

• Breast cancer arises in the breast tissue and predominantly affects women. Symptoms can include a lump in the breast or armpit, breast pain, bloody discharge from the nipple, and alterations in the shape or texture of the breast or nipple skin. 
• Treatment options depend on the cancer stage and may involve a combination of chemotherapy, radiation, hormone therapy, and surgery. Metastatic breast cancer is classified as advanced stage IV, indicating that it has spread to distant organs or lymph nodes beyond the breast.

Prostate Cancer:

• Prostate cancer is a type of cancer that occurs in the prostate gland of men. Symptoms often include difficulties with urination. Some prostate cancers grow slowly, and in these cases, active monitoring may be recommended. Others can be aggressive and require treatment options such as radiation, surgery, hormone therapy, or chemotherapy.
• The stages of prostate cancer are classified based on how far the cancer has spread, typically ranging from I to IV:
• Stage I : Cancerous cells are confined to the prostate.
• Stage II : Cancer remains in the prostate but may have a higher likelihood of spreading than in Stage I.
• Stage III : Cancer has extended beyond the prostate, potentially affecting the seminal vesicles.
• Stage IV : Cancer has metastasized to other tissues, such as the rectum, urethra, or pelvis.
• Some stages, like IA, IB, IC, IIA, or IIB, can be further subdivided for more precise classification.

Neuroendocrine Tumor:

• Neuroendocrine tumors arise when neuroendocrine cells develop into abnormal growths. These tumors can be slow-growing or aggressive and have the potential to spread to other parts of the body. 
• They primarily originate in the lungs, pancreas, small intestine (including the duodenum and ileum), and large intestine (rectum and colon). Many individuals do not exhibit symptoms, and tumors are often discovered incidentally. 
• When symptoms do occur, they can vary depending on the tumor's location and may include rare instances of skin flushing, breathing difficulties, diarrhea, or fluctuating blood sugar levels.

7.0Cancer Diagnosis

• Physical Exam : During a physical exam, healthcare providers look for abnormalities, such as changes in skin color or organ enlargement, that may indicate cancer.
• Laboratory Tests : Tests such as blood and urine analyses can reveal abnormalities linked to cancer. For example, a complete blood count may show unusual white blood cell levels in individuals with leukemia.
• Imaging Tests : Non-invasive imaging tests, including CT scans, bone scans, MRIs, PET scans, ultrasounds, and X-rays, help visualize bones and internal organs.
• Biopsy : A biopsy involves collecting a cell sample for laboratory analysis. The method used depends on the cancer type and location, and it is often the definitive way to diagnose cancer. In the lab, normal cells appear uniform and organized, while cancer cells show irregular sizes and disorganized structures.

8.0Cancer Treatment

• Treatment options vary based on the cancer type and stage, and they may include:
• Surgery : Aimed at removing the cancer or as much of it as possible.
• Chemotherapy : Utilizes drugs to kill cancer cells.
• Radiation Therapy : Employs high-energy beams (like X-rays and protons) to destroy cancer cells. This can be delivered externally or through internal methods (brachytherapy).
• Bone Marrow Transplant : Also known as stem cell transplant, this procedure replaces damaged bone marrow with healthy cells, either from the patient or a donor.
• Immunotherapy : Sometimes referred to as biological therapy, it helps the immune system recognize and fight cancer.
• Hormone Therapy : Used for cancers influenced by hormones (like breast and prostate cancer), this treatment aims to remove or block hormone effects, potentially slowing cancer growth.