Things to know about cancer
Cancer refers to a collection of a large number of diseases characterized by the development of abnormal cells that divide uncontrollably and can infiltrate and destroy the normal body tissue.
Cancer can often spread throughout your body. It develops when the body’s normal growth control mechanisms stop working. Unlike normal body cells, cancer cells are immortal. These extra cells continue to multiply and may form a mass of tissue called a tumor. Moreover, these cells compete with the normal body cells for nutrition and oxygen and cause starvation of the normal cells.
Some types of cancer, such as leukemia, do not form tumors. Leukemia is the second leading cause of death in the world. Survival rates are improving for many types of cancer because of improvements in cancer screening and cancer treatment. Cancer does not have one single cause. There are usually multiple causes and risk factors involved.
There are over 200 types of cancers.
5 Main categories of cancer
Cancer may occur anywhere in the body. In women, breast cancer is one of the most common. In men, it’s prostate cancer. Lung cancer and colorectal cancer affect both men and women in high numbers.
There are five main categories of cancer:
- Carcinoma: It begins in the skin or tissues that line the internal organs.
- Sarcoma: It develops in the bone, cartilage, fat, muscle, or other connective tissues.
- Leukemia: It begins in the blood and bone marrow.
- Lymphoma: It arises from the immune system.
- Central nervous system cancer: It develops in the brain and spinal cord.
The following table (National Cancer Institute 2022) gives the estimated numbers of new cases and deaths for each common cancer type:
|Cancer Type||Estimated New Cases||Estimated Deaths|
|Breast (Female -- Male)||287,850 - 2,710||43,250 - 530|
|Colon and Rectal (Combined)||151,030||52,580|
|Kidney (Renal Cell and Renal Pelvis) Cancer||79,000||13,920|
|Leukemia (All Types)||60,650||24,000|
|Lung (Including Bronchus)||236,740||130,180|
The three most common cancers in men, women, and children in the U.S. are as follows:
- Men: Prostate, lung, and colorectal
- Women: Breast, lung, and colorectal
- Children: Leukemia, brain tumors, and lymphoma
For more information, read our full medical article about cancer signs, symptoms, treatment, and prognosis.
Causes of cancer
Cancer is caused by changes (mutations) in the DNA within the cells. The DNA inside the cell is packaged into many individual genes, each of which contains a set of instructions telling the cell what functions to perform and how to grow and divide. Errors in the instructions can cause the cell to stop its normal function and may allow it to become cancerous.
A gene mutation can instruct a healthy cell to
- Allow rapid growth
- Fail to stop uncontrolled cell growth
- Make mistakes when repairing DNA errors
Nonmodifiable risk factors include
- Genetic inheritance: Many types of cancer run in the family. The reason may be a faulty gene. For example, BRCA mutation is associated with familial breast cancer.
- Familial cancer syndrome: Some types of syndrome such as Von Hippel–Lindau and familial polyposis coli may be responsible for cancer development in the family.
- Age: As a rule, the risk of cancer increases as you age. This may be because of the inability of a mutated cell to repair itself in old age.
Exposure to any predisposing factors (modifiable risk factors) such as
- Radiation exposure (diagnostic, occupational, or therapeutic)
- Viruses (human papillomavirus)
- Carcinogens (cancer-causing chemicals such as many industrial solvents [benzene])
- Heavy metals (arsenic, lead, and cadmium are blamed for kidney cancer and some bone cancer)
- Hormonal influence (prostate cancer is often androgen-dependent)
- Chronic inflammation (Crohn’s disease or ulcerative colitis and colon cancer)
- Environmental pollution (radon and lung cancer)
- Exposure to ultraviolet (UV) light and skin cancer
It is prudent to remember that we are yet to find out what exactly leads to failure in the cell division and replication that leads to cancer. Having a risk factor does not mean you will get cancer. Similarly, you may get a certain type of cancer even in absence of any risk factor.
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Siegel RL, Miller KD, Fuchs HE, Jemal A. Cancer statistics, 2022. CA: A Cancer Journal for Clinicians 2022; 72(1):7-33. Last accessed May 10, 2022. [PubMed Abstract]
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Bone CancerBone cancer is a rare type of cancer that occurs in cells that make up the bones. Primary bone cancer that arises in bone cells is different than metastatic bone cancer, which is cancer that arises in another part of the body and then spreads to the bones. Hereditary and environmental factors likely contribute to the risk of bone cancer. Signs and symptoms of bone cancer may include pain, the presence of a mass or lump, and bone fractures. There are different types of bone cancer (osteosarcoma, chondrosarcoma, Ewing's sarcoma, pleomorphic sarcoma, fibrosarcoma). Treatment for bone cancer may include surgical removal of the tumor, chemotherapy, radiation, and/or a stem cell transplant. The prognosis for bone cancer depends on the type of cancer and the extent of spread.
Breast cancer is an invasive tumor that develops in the mammary gland. Breast cancer is detected via mammograms, breast self-examination (BSE), biopsy, and specialized testing on breast cancer tissue. Treatment of breast cancer may involve surgery, radiation, hormone therapy, chemotherapy, and targeted therapy. Breast cancer risk may be lowered by managing controllable risk factors.
What you should know about breast cancer
- Breast cancer is the most common cancer among American women.
- One in every eight women in the United States develops breast cancer.
- There are many types of breast cancer that differ in their capability of spreading (metastasize) to other body tissues.
- The causes of breast cancer are unknown, although medical professionals have identified a number of risk factors.
- There are 11 common types of breast cancer and 4 uncommon types of breast cancer.
- Breast cancer early signs and symptoms include
- a lump in the breast or armpit,
- bloody nipple discharge,
- inverted nipple,
- orange-peel texture or dimpling of the breast's skin (peau d'orange),
- breast pain or sore nipple,
- swollen lymph nodes in the neck or armpit, and
- a change in the size or shape of the breast or nipple.
- Breast cancer can also be symptom free, which makes following national screening recommendations an important practice.
- Breast cancer is diagnosed during a physical exam, by a self-exam of the breasts, mammography, ultrasound testing, and biopsy.
- Treatment of breast cancer depends on the type of cancer and its stage (0-IV) and may involve surgery, radiation, or chemotherapy.
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Cancer Risk Factors and CausesThough it's difficult to say why some people develop cancer while others don't, research shows that certain risk factors increase a person's odds of developing cancer. These risk factors include growing older, family history of cancer, diet, alcohol and tobacco use, and exposure to sunlight, ionizing radiation, certain chemicals, and some viruses and bacteria.
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Liver CancerLiver cancer is cancer of the liver cells (hepatocellular carcinoma) or of the ducts in the liver (cholangiocarcinoma). Liver cancer often arises due to liver damage, cirrhosis (scarring) caused by alcohol use/abuse, hepatitis B, or hepatitis C. Liver cancer may not cause any symptoms. Liver cancer is diagnosed with blood tests, imaging tests, and a liver biopsy. Treatment for liver cancer may include surgery, ablation, embolization, radiation, chemotherapy, and targeted therapy.
Lung CancerLung cancer kills more men and women than any other form of cancer. Eight out of 10 lung cancers are due to tobacco smoke. Lung cancers are classified as either small-cell or non-small-cell lung cancers.
Melanoma (Skin Cancer)Melanoma is a type of skin cancer which begins in skin cells called melanocytes and affects more than 53,600 people in the United States each year. These melanocytes can grow together to form benign moles which, after a change in size, shape, or color can be a sign of melanoma. Caused by sun exposure, early detection becomes extremely important to avoid a spread to other areas of the body. Diagnosis is confirmed through a biopsy of the abnormal skin and treatment depends on the extent and characteristics of the patient. Metastatic melanoma is melanoma that has spread to various organs.
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Prostate Cancer Facts
Prostate cancer is a leading cause of cancer and cancer death in males; in some men, identifying it early may prevent or delay metastasis and death from prostate cancer.
- The prostate is a walnut-shaped gland that is a part of the male reproductive system that wraps around the male urethra at it exits the bladder.
- Prostate cancer is common in men over 50 years of age, with the risk of developing prostate cancer increases with aging.
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