Among the entire diseases, cancer ranks high as a major killer worldwide.Cancers are a large family of diseases that includes the abnormal cell growth with the potential to invade or spread to other parts of the body. The term cancer derives from the Greek word (Karkinoma) for crab, by Hippocrates used to describe the appendage-like projections extending from tumors. Cancer refers to a disease of cells that show uncontrolled proliferation, dedifferentiation (anaplasia), invasiveness and the ability to metastatis . Not all tumors are cancerous; benign tumors do not spread to other parts of the body. The branch of science dealing with the study of neoplasms or tumours is called oncology.
Neoplasm may be:
Benign
When they are slow-growing and localised without causing much difficulty to the host.
Malignant
When they proliferate rapidly, spread throughout the body and may eventually cause death of the host.
Tobacco use is the source of about 22% of cancer deaths. Another 10% is due to a poor diet, obesity, lack of physical activity, and alcohol consumption. Other factors include ionizing radiation, certain infections, and environmental pollutants. In the developing world nearly 20% of cancers are due to infections such as human papillomavirus (HPV), hepatitis B and hepatitis C. These factors act by changing the genes of the cell. Usually many such genetic changes are required before cancer develops. Approximately 5–10% of cancers are owing to genetic defects inherited from a person’s parents. Cancer can be diagnosed by certain signs and symptoms or screening tests. It may be further investigated by medical imaging and confirmed by biopsy.
In 2012 about 14.1 million of new cancer cases occurred globally (not including skin cancer other than melanoma). It results about 8.2 million deaths or 14.6% of all human deaths. The most common types of cancer in males are prostate cancer, colorectal cancer, lung cancer, and stomach cancer, and in females, the most common types are lung cancer ,breast cancer, colorectal cancer, and cervical cancer. When skin cancer other than melanoma were incorporated in total new cancers each year it would account for about 40% of cases. In children, brain tumors and acute lymphoblastic leukaemia are most common except in Africa where non-Hodgkin lymphoma appears more often. In 2012, about 165,000 children under the age of 15 years were diagnosed with cancer. The threat of cancer increases appreciably with age and many cancers occur more commonly in developed countries.The economical costs of cancer have been determined at $1.16 trillion US dollars per year as of 2010.
SIX HALL MARKS OF CANCER
• Cell growth and multiplication without the proper signals to do so
• Continuous growth and division even when there are signals bring to an end
• Avoidance of the programmed cell death
• Unlimited number of cell divisions
• Promoting blood vessel construction
• Invasion of tissue and development of metastases
The progression from normal cells to cells that can form a detectable crowd to outright cancer involves multiple steps known as malignant progression.
TYPES OF TUMOURS
Tumors can be benign or malignant. Benign tumours are generally slow growing, resemble normal cells,remain localised and are usually not harmful.The terms cancer or malignant neoplasm or malignant tumour are synonymous.They proliferate rapidly,manifest dedifferentiation,invasiveness, and the capacity to metastasise.They cause damage on the surrounding cells and are harmful if left untreated.
Cancers are classified based on
The Origin of the tumor. These types include:
Benign tumours names usually end with “oma”, for example Papilloma (from surface epithelium), Adenoma (from glandular epithelium), Melanoma (from pigment cells), Myoma (from muscle tissue), Fibroma (from fibrous tissue) Neurofibroma (from nerve sheath) and Aleiomyoma (from smooth muscle cells) ,etc.
Malignant neoplasms are either Solid tumours or Haematological malignancies.
• Carcinoma: Derived from epithelial cells,most common cancers,mainly in the aged,in the breast, prostate, lung, pancreas, and colon.
• Blastoma: Derived from immature “precursor” cells or embryonic tissue and are more common in children than in older adults.
• Leukemia and lymphoma: These two types of cancer arise from hematopoietic (blood-forming) cells and be likely to mature in the blood and lymph nodes, respectively. Leukemia is the most common type of cancer in children accounting for about 30%.
• Germ cell tumor: Derived from pluripotent cells, occurs in the ovary or the testicle (dysgerminoma and seminoma, respectively).
• Sarcoma: Arises from connective tissue (i.e. cartilage, bone, fat, nerve), each of which develops from cells originating in mesenchymal cells outer the bone marrow.
Types of cancer classified by body system
Cancer has the potential to affect each organ in the body. The cells inside the malignant tumours have the capability to invade neighbouring tissues and organs, thus spreading the disease. It is also possible for cancerous cells to break free from the tumour and enter the bloodstream, entering to the body organs.
1. Blood cancer: These cancers are also known as leukemia or lymphoma.
• Leukemia.
• Lymphoma.
• Multiple Myeloma
• Waldenstrom’s Macroglobulinemia
2. Bone cancer: It is rare type of cancer. It affects both children and adults. Common type of cancer are
• Ewings sarcoma
• Osteosarcoma
3. Brain cancer: Brain cancers are malignant or benign. They affect both children and adults. It spread only in brain.
• Brain tumour
• Brain Stem Glioma, Childhood
• Cerebellar Astrocytoma, Childhood
• Cerebral Astrocytoma/Malignant Glioma, Childhood
• Ependymoma, Childhood
• Medulloblastoma, Childhood
4. Breast cancer: It is a common type of cancer, mainly affect females. Common types of breast cancers are
• Ductal carcinoma in situ
• Lobular carcinoma in situ
• Inflammatory breast cancer
• Paget’s disease of the nipple
5. Digestive cancers: Also known as gastrointestinal cancers. It is a broad group of cancer that affects all the parts from oesophagus to anus. All cancers are specific and have its own symptoms. They are
• Anal cancer
• Bile Duct Cancer, Extra hepatic
• Carcinoid Tumour, Gastrointestinal
• Colon Cancer
• Gall bladder Cancer
• Oesophageal Cancer
• Liver Cancer
• Pancreatic Cancer
• Rectal Cancer
• Small Intestine Cancer
• Stomach (Gastric) Cancer
6. Endocrine cancers: The most common type is thyroid cancer. The other types are
• Adrenocortical Carcinoma
• Islet Cell Carcinoma (Endocrine Pancreas)
• Parathyroid Cancer
• Pheochromocytoma
• Pituitary Tumour
• Thyroid Cancer
7. Eye Cancer: It will affect both children and adults.
• Melanoma, Intraocular
• Retinoblastoma
8. Genitourinary cancers: It affects the male genitalia and urinary tract.
• Bladder Cancer
• Kidney (Renal Cell) Cancer
• Penile Cancer
• Prostate Cancer
• Renal Pelvis and Ureter Cancer, Transitional Cell
• Testicular Cancer
• Urethral Cancer
• Wilms’ Tumour and Other Childhood Kidney Tumours
9. Gynaecological cancers: It will affect the organs of female reproductive system.
• Cervical Cancer
• Endometrial Cancer
• Ovarian Cancer
• Vaginal Cancer
• Vulvar Cancer
10. Head and Neck cancers: This cancer affects the moist surface of neck and head. Cigarette smoking plays important role in this cancer.
• Hypo pharyngeal Cancer
• Laryngeal Cancer
• Lip and Oral Cancer
• Metastatic Squamous Neck Cancer
• Nasopharyngeal Cancer
• Oropharyngeal Cancer
• Paranasal Sinus and Nasal Cavity Cancer
• Parathyroid Cancer
• Salivary Gland Cancer
11. Respiratory cancers: Cigarette smoking is the main reason for cancer affecting respiratory system.
• Lung Cancer
• Malignant Mesothelioma
• Thymoma and Thymic Carcinoma
12.Skin cancer: The UV rays from sun are one of the main reasons for skin cancer.
• Cutaneous T-Cell Lymphoma
• Melanoma
• Non-Melanoma Skin Cancer
SIGNS AND SYMPTOMS
Symptoms of cancer metastasis depend on the location of the tumor.
•
• When cancer begins, it regularly produces no symptoms. Signs and symptoms only appear as the mass continues to grow or ulcerates.
1. Local effects
Local symptoms may occur due to the mass of the tumor or its ulceration. For example, mass effects from lung cancer can cause blockage of the bronchus results in cough or pneumonia; esophageal cancer can cause narrowing of the esophagus, makes it difficult or painful to swallow; and colorectal cancer can lead to narrowing or blockages in the bowel, results in changes in bowel habits. Masses in breasts or testicles may be easily felt.
Ulceration can cause
• bleeding in the lung, will leads to coughing up blood
• in the bowels to anemia or rectal bleeding
• in the bladder to blood in urine and
• in the uterus to vaginal bleeding.
Even though localized pain may present in advanced cancer, the initial swelling is normally painless. Several cancers can cause a buildup of fluid within the chest or abdomen.
• Systemic symptoms
• General symptoms arise due to distant effects of the cancer that are not linked to direct or metastatic spread. These may include: unintentional weight loss, fever, being excessively tired, and changes to the skin. Hodgkin disease, leukemias , and cancers of the kidney or liver can cause a persistent fever of unknown origin. Some cancers may cause specific groups of systemic symptoms, termed paraneoplastic phenomena. Examples include the appearance of myasthenia gravis in thymoma and clubbing in lung cancer.