Cancer: True or False statements

• Neoplasia literally means "new growth".
• Techncially, neoplasia is an abnormal mass of tissue with growth exceeding and uncoordinated with normal tissues.
• The growth persists in the excessive manner after cessation of the stimulus, evoking transformation.
• Oncology is the study of tumors or neoplasms.
• Origin of neoplasms is linked to heritable genetic changes permitting excessive, unregulated proliferation independent of normal growth stimuli.
• Neoplasms display autonomy, steadily increasing in size regardless of the environment and the host's nutritional status.
• Not all new growths are neoplasms.
• Examples of new growth of tissues and cells can happen during embryogenesis, regeneration and repair, hyperplasia, and hormonal stimulation.
• Normal adult cell proliferation and maturation are controlled.
• Neoplastic cells lose control and regulation of replication, forming an abnormal mass.
• The capacity of cells to divide allows them to be divided into 3 groups including Labile Cells, Stable Cells and Permanent Cells.
• Labile cells continue to multiply throughout life under normal physiologic conditions like surface epithelial cells, and hematopoietic cells.
• Stable cells decrease or lose their ability to proliferate after adolescence, but they keep the capacity to multiply in response to stimuli throughout adult life.
• Stable cells are the parenchymal cells of organs, such as liver, pancreas, kidneys, adrenal and thyroid, and mesenchymal cells.
• Permanent cells lose their ability to proliferate around the time of birth, like neurons, skeletal and cardiac muscle cells.
• A neoplasm is a mass of tissue resulting from abnormal, excessive, uncoordinated and autonomous proliferation of cells even after cessation of growth stimulus.
• Neoplasms may be benign, growing slowly and remaining localized.
• Neoplasms may be malignant, proliferating rapidly, spreading throughout the body, and causing death.
• All tumors, whether benign or malignant, have two components including parenchyma and supportive stroma.
• The Parenchyma determines the nature and evolution of the tumor.
• The Supportive Stroma provides the framework on which the parenchymal tumor cells grow.
• Neoplasms are named upon two factors, the histologic or behavioral patterns
• The suffix "-oma" denotes a benign mesenchymal neoplasm. Examples:
  • Muscle results in Rhabdomyoma
  • Bone results in Osteoma
  • Fat results in Lipoma
  • Blood vessel results in Hemangioma
  • Nerve results in Neuroma
  • Fibrous tissue results in Fibroma
  • Cartillage in Chondroma
• Benign epithelial neoplasms are classified on the basis of cell of origin.
• Adenoma is a term for benign epithelial neoplasm that form glandular pattern or on basis of microscopic or macroscopic patterns.
• Visible finger like or warty projection from epithelial surface are referred to as papillomas.
• Malignant neoplasms of epithelial cell origin derived from any of the three germ layers are called carcinomas.
• Malignant neoplasms can originate from the ectoderm such as in skin (squamous cell carcinoma, basal cell carcinomal).
• Malignant neoplasms can originate from the mesoderm such as from renal tubules in renal cell carcinoma.
• Malignant neoplasms origin can be from the endoderm such as the lining of the gastrointestinal tract, resulting in colonic carcinoma.
• Some malignant, glandular microscopic picture neoplasms are called Adeno carcinomas.
• Recognizable squamous cells turn into Squamous cell carcinoma.
• Malignant neoplasms arising from mesenchymal tissues are called sarcomas, and these neoplasms are named fibrosarcoma, liposarcoma, osteosarcoma, hemangiosarcoma etc.
• Some exceptional nomenclatures include:
  • Non-neoplastic misnomers such as Hematoma, Granuloma, Hamartoma, mycetoma.
  • Malignant misnomers such as Melanoma, Lymphoma, Seminoma, Glioma, Hepatoma.
  • The suffix for neoplastic disorders of blood cells is 'aemia' such as leukaemia.
• tumors arise from more than tissue components such as Teratomas.
• Teratomas contain representative of parenchyma cells of more than one germ layer, usually all three, and arise from tot potential cells so are principally encountered in ovary and testis.
• Other tumors arise from more than tissue components such as Mixed tumors, containing both epithelial and mesenchymal components like pleomorphic adenoma and fibroadenoma.
• Summary of nomenclature:
  • Benign tumours of epithelial origin are called either Adnomas or Papiloma depending on the type of the epithelial tissue type.
  • Malignant tumours of epithelial origin are called carcinomas.
  • The suffix '-oma' is added to denote Benign mesenchymal Tumours.
  • Malignant mesenchymal tumours are named sarcomas (sarcos = fleshy).
• Neoplasm is the broadest term encompassing all abnormal cell growths, while tumors refer to solid neoplasms only.
• Cancer is specifically for malignant neoplasms.

Characteristics of Benign and Malignant Neoplasms

• Differentiation refers to the extent to which neoplastic parenchymal cells resemble the corresponding normal parenchymal cells, lack of differentiation is called anaplasia.
• Benign tumors are well differentiated, while malignant neoplasm could be range from well differentiated to undifferentiated.
• Dysplasia is a term used to describe disorderly but non-neoplastic proliferation principally in the epithelia which has a loss in the uniformity of individual cells and in their architectural orientation.
• The growth rate of tumors relates to the level of differentiation.
• Most malignant tumors grow more rapidly than do benign lesions, the benign tumors can higher growth rate than malignant tumors
• Factors may affect their growth such as hormonal stimulation, adequacy of blood supply, and unknown influences may affect their growth.
• Benign tumors remains localized to their site of origin, do not have the capacity to infiltrate, while Benign tumors usually develop a rim of compressed connective tissue called a fibrous capsule.
• The growth of malignant neoplasms is accompanied by progressive infiltration, invasion and destruction of the surrounding tissue, and poorly demarcated from the surrounding normal tissue.
• Invasiveness is the most reliable feature that differentiates malignant from benign neoplasms.
• Carcinoma in situ is an epithelial neoplasm exhibiting all the cellular features associated with malignancy, but which has not yet invaded through the epithelial basement membrane.
• Carcinoma in situ detection is used in population screening programmes for cervical, breast and some other carcinomas.
• Metastasis is a transfer of malignant cells from one site to another not directly connected with it.
• Metastasis is the most reliable sign of malignancy.
• Organs least favored for metastatic spread include striated muscles and spleen. Approximately 30% of newly diagnosed patients with solid tumors present with metastasis.
• In general, more aggressive neoplasms can also metastasise.

Pathways of Spread

• Dissemination of cancers may occur through one of three pathways: Direct seeding of body cavities or surfaces/ transcoelomic spread, Lymphatic spread, and Hematogenous spread.
• Direct seeding of body cavities and surfaces such is particularly characteristic of carcinomas arising in the ovaries such as Krukenberg tumour and Pseudomyxoma peritoni.
• Transport through lymphatics is the most common pathway for the initial dissemination of carcinomas, and sarcomas. Carcinoma metastasize to Axilary Lymph nodes, and Cancers of Breast metastasizes to Inner Mammary arteries.
• The pattern of lymph node involvement follows the natural routes of lymphatic drainage.
• Skip metastasis occur when local lymph nodes may be bypassed and occasionally found in lymph node distant from the site of the primary malignant neoplasm.
• A "sentinal lymph node" is defined as the first lymph node in a regional lymphatic basin that receives lymph flow from a primary tumor.
• Hematogenous spread is typical of sarcomas but is also seen with carcinomas.
• Arteries, with their thicker walls, are less readily penetrated than are veins.
• Lung & liver are common sites of metastasis because they receive the systemic and venous out flow respectively.
• Renal cell carcinoma invades the branches of the renal vein, Breast carcinoma is more likely to metastasize into bone.
• Spleen is unfavorable site for hematagenous spread due to open sinusoidal pattern which does not permit tumor cells to stay there.

Epidemiology and Factors in Cancer

• The only certain way to avoid cancer is not to be born.
• Screening procedures for cervical and brest cancer have resulted in increased cancer detection and treatment.
• The most common tumors in Men tend to arise in the prostate, lung, and colorectum while in Women tumors are of breast, lung, and colon and rectum.
• Most cancers in adults occur in those over 55 years of age.
• In children under 15 years of age cancers can be more susceptible when it comes to Acute leukemia, central nervous system tumours, Neuroblastoma, wilm's tumour, Retinoblastoma, and rhabdomyosarcoma.
• Geographic differences in stomach carcinoma is most common in Japan, lung cancer is USA, and skin cancer in New zeland and Australia
• Environmental factors include:
  • Asbestos causing lung cancer
  • Vinyl chloride causing angiosarcoma
  • Benzene causing leukemias
  • Cadmium and cadmium compounds causing prostatic cancer
  • Cigarette smoking causing brochogenic carcinoma
  • Venereal infection (HPV) causing cervical carcinoma
  • Radon and its decay products causing lung cancer
  • Ethylene oxide causing Leukemia
• Premalignant heredity disorders are categorized in to three groups such as familial retinoblastomas, familial adenomatous polyps.
• Premalignant heredity disorders are categorized in 3 groups such as E.g. Breast, ovarian, colonic, and brain cancers
• Autosmal recessive syndromes of defective DNA repair are characterized by chromosomal instability caused by Ataxia telaangietasia and Fanconi anemia
• Acquired preneoplastic disorders include endometrial hyperplasia, and Regenerative nodules.

Molecular Basis of Cancer (Carcinogenesis)

• The fundamental principle includes Non-lethal genetic damage
• Three classes of normal regulatory genes include growth promoting genes and, Genes that regulate DNA repait.
• Growth promoting proto-oncogenes include which activate Activation of proto-oncogenes which gives rise to point mutation while, Gene amplification and translocation, Inversion.
• Cancer suppressor genes are important due that its inactivation is the event in cancer genesis, for example: P53.
• The process of carcinogenesis is multi-factorial at both phenotypic and genotypic levels.
• Large number of agents cause genetic damages and transform cells such as chemical carcinogenesis, and Viral carcinogenesis.
• Chemical carcinogenic agents fall into two categories, directly and indirectly acting compounds.
• Indirect acting compounds require metabolic conversion in vivo to produce ultimate carcinogens - examples of this group are aromatic amines, polycyclic aromatic hydrocarbons.
• Examples of proven chemical carcinogens are Lung cancer caused by Polycyclic, Bladder cancer caused by Aromatic amines.
• Radiation carcinogenesis may be caused by ultraviolet (UV) or ionizing electromagnetic (X rays and gamma rays).
• Ultraviolet rays can induce vibration, increased of squamous cell carcinoma, basal cell carcinoma and possibly malignant melanoma caused by intensity of exposure.
• UV rays have a carcinogenic effect due to its formation of pyrimidine in DNA, and can cause inhibition of cell division.
• Occupational hazards for radiation includes skin cancers ,and Thyroid cancer
• Microbial Carcinogenesis is caused by RNA viruses ,Fungus, such as Helicobacter Pylori, Aspergillus flavus
• Examples tumors are Human wart ,Kaposi's sarcoma by human herpes virus-8.
• HPV is linked to oral and laryngeal,squamous 85% cell carcinomas is linked to 85%.
• Hepatitis B- virus (HBV is caused by transmission of infected T cells through sexual intercourse or breast feedings.

Clinical Features, Screening and Prevention

• Both benign and malignant neoplasms may problems because of Location, hormones and or Bleeding.
• Cancer cachexia is a patient having profound weakness from the from low food or calorie expenditures.
• Paraneoplastic syndromes aggregate in bearing patients that result in high calorie expenditure, they be the be hard to identify but can be lethal. Hypercalcimia, can be identified as sign of syndrome ,for three reasons.
• Grading denotes the level of differentiation.
• Cancers are classified into grades I and V, and can be examined , Investigations like TNM.
• N3 nodes are involved while stages TO can only have small primary.
• Screening for cancer is performed by mammogram and is recommended for woman. Prevention of cancer can be screened for genetic risk, and use checkup for signs for stages.
• Some preventive measures include, smoking and high.
• HPV Vaccine are good to intake for prevention of most type of cancers is linked with HPV transmission.

Test your knowledge of cancer with this true or false quiz. Topics covered includes lesion detection, metastasis, gene mutation, neoplasms, spread and differentiation of tumors. See how well you know cancer!