Thursday, 3 December 2020

·         Tumors, which in the past has been used as a non-neoplastic term as used by Celsus in describing the cardinal signs of Inflammation to mean swelling but its use now is equated with Neoplasm
·         The Greek word “oncos” means “swelling” and where we get the word oncology or oncologist.
·         The word “cancer” comes from the Latin Word for “crab”, is a term used mainly for Malignant tumors

2. Neoplasia

· It derived from 2 Greek words

Neos = New

Plasia = Thing Formed

o Hence, Neoplasia in simple terms means the process of forming new things or simply, new growth.

“A neoplasm is an abnormal mass of tissue, it’s growth exceeds and is uncoordinated with that of the normal tissue and persist in the same excessive manner after cessation of the stimuli which evoke the change.”

(Dr. RA Willis)

3. Features of Neoplasm

· Excessive cellular proliferation

· Autonomous growth - uncoordinated

· Derived from cells with proliferative capacity (active cell cycle)

· Results from alterations in DNA

· Some resemblance to cell of origin

Epidemiology of Cancer

4. Introduction

Cancer is a group of more than 200 diseases characterized by uncontrolled and unregulated growth of cells.

Cancer is often considered a disease of aging, with the majority of cases (77%) diagnosed in those over age 55 years, it occurs in people of all ages.

5. The global burden of cancer

6. Global Cancer Incidences 2018

7. Global Cancer Mortality 2018

8. Percentages of new cases
by type, region and sex

9. Five Most commonly diagnosed cancer

10. Global Cancer Incidences in Male 2018

11. Global Cancer Incidences in Female 2018

12. The National burden of cancer

· Estimated number of people living with the disease: around 2.25 million

· Every year, new cancer patients registered: Over 11,57,294 lakh

· Cancer-related deaths: 7,84,821

o Men: 4,13,519

o Women: 3,71,302

13. The National burden of cancer

· Cancers of oral cavity and lungs account for over 25% of cancer deaths in males and

· Cancer of breast and oral cavity account for 25% cancers in females.

· The top five cancers in men and women account for 47.2% of all cancers;

· these cancers can be prevented, screened for and/or detected early and treated at an early stage.

14. The National burden of cancer

15. The National burden of cancer

· One woman dies of cervical cancer every 8 minutes in India.

· For every 2 women newly diagnosed with breast cancer, one woman dies of it in India.

· Mortality due to tobacco use in India is estimated at upwards of 3500 persons every day.

· Tobacco (smoked and smokeless) use accounted for 3,17,928 deaths (approx) in men and women in 2018.

Biology of Cancer

“The adult human body contains over 100 trillion cells.”

About three billion of those cells die—and most are replaced—every minute.

16. Cell

· Cells are the simplest units of all living matter.

o Some exist as independent organisms. (such as microscopic amoeba and bacteria)

o Others function only when part of a larger organism. (such as the cells of the human body)

· These tiny forces of life do more than give the body structure.

· They also orchestrate all of the processes that make life possible: respiration, movement, reproduction, digestion, and excretion.

· The body employs a vast array of cell types to accomplish these varied tasks.

· In fact, the human body consists of about 200 different types of cells. These cells vary greatly in size and shape, both of which are dictated by the cell’s function.

17. The Basic Structures of the Cell

18. Cell Growth and Reproduction

19. Biology of Cancer

· The body normally functions within an orderly system of cell division and cell death.

· When cells multiply faster than they die, abnormal growths (tumors) result.

· Two major dysfunctions in the process of cancer development are

o Defective cell proliferation (growth) and

o Defective cell differentiation

20.Defective cell proliferation (growth)

· The normal body’s cells proliferation (growth) are controlled by-

o An intracellular mechanism that determines the necessity of cell proliferation

§ Under normal conditions, a state of dynamic equilibrium

· i.e., cell proliferation equals cell degeneration or death.

· So, process of cell division and proliferation is activated only in the presence of cell degeneration or death.

§ Under physiologic need, Cell proliferation also occurs.

· For example, a normal increase in WBC count in case of infection.

o Contact Inhibition

§ Normal cells respect the boundaries and territory of the cells surrounding them.

§ inhibit cell growth through the physical contact of the surrounding cell membranes.

21. Defective cell proliferation (growth)

· The cancer cells Defective proliferation (growth) -

· Pyramid effect

o In most situations, cancer cells multiply at the same rate as the normal cells from which they originate but respond differently to intracellular signals regulating equilibrium

o Proliferation is indiscriminate and continuous.

o Each cell division creates two or more offspring cells.

o Because of this there is continuous growth of a tumour mass

· Loss of contact inhibition

o No regard for cell boundaries and Grow on top of one another and on top of or between normal cells

22. Defective cell differentiation

· Cell differentiation

o all body cells are derived from the fertilized ova,

§ all cells have the potential to perform all body functions.

§ As cells differentiate, this potential is repressed, and the mature cell is capable of performing only specific functions.

o there is a stable and orderly phasing out of cell potential.

o Under normal conditions the differentiated cell is stable and will not dedifferentiate.

o Two types of normal genes that control the differentiation and proliferation, those are protooncogenes and tumor suppressor genes.

23. Defective cell differentiation

· Protooncogenes

o Normal cellular genes that are important regulators on normal cellular processes, that promote growth.

o Mutations that alter their expression, can activate them to act as oncogenes (tumor-inducing genes)

o It works as the genetic lock that keeps the cell in its mature functioning state.

o When this lock is “unlocked,” due to exposure to carcinogens and mutations occur. The abilities and properties that the cell had in fetal development are again expressed and cell regains a fetal appearance and function.

24.Defective cell differentiation

· Tumor suppressor genes

o Regulate cell growth by ‘growth Suppression’.

§ i.e. prevent cells from going through the cell cycle.

o Mutations render them inactive

o Examples of mutation in tumor suppressor genes that increase the risk of cancer -

§ BRCA1 and BRCA2 - breast and ovarian cancer.

§ APC gene - colorectal cancer.

§ p53 - bladder, breast, colorectal, esophageal, liver, lung, and ovarian cancers.

Cancer Cells and Normal Cell Characteristics

25. Development of Cancer

· Chemical, environmental, genetic, immunologic, viral, or spontaneous in origin

· Initiation

o Mutation of genetic structure

o Has potential to develop into clone of neoplastic cells

26.Development of Cancer

· Promotion

o Characterized by the reversible proliferation of altered cells

o Activities of promotion (e.g. obesity, smoking, alcohol) are reversible

o Latent period

o Initial genetic alteration to clinical evidence of cancer

27. Development of Cancer

· Progression

o Characterized by increased growth rate of tumor as well as its invasiveness and metastasis

o Metastasis = spread of cancer from primary (initial) site to distant site

§ Metastasis process begins with rapid growth of primary tumor

§ Tumor angiogenesis - formation of blood vessels within the tumor; critical for tumor survival

28.Development of Cancer

The pathogenesis of cancer metastasis.

29.References

1. Lewis SM, Dirksen SR, Heitkemper MM, Bucher L, Harding M. Medical-surgical nursing: assessment and management of clinical problems. Ninth edition. St. Louis, Missouri: Elsevier/Mosby; 2014. p. 247-253

2. Smeltzer SC, Hinkle JL, Bare BG, Cheever KH, editors. Brunner & Suddarth’s textbook of medical-surgical nursing. Volume 2: Twelfth edition. Philadelphia Baltimore New York London Buenos Aires Hong Kong Sydney Tokyo: Wolters Kluwer/Lippincott Williams & Wilkins; 2010. p. 336-342

3. Nettina SM, editor. Lippincott manual of nursing practice. 10th ed. Philadelphia: Wolters Kluwer Health/Lippincott Williams & Wilkins; 2014. p. 134-137

4. World Health Organization: WHO. Cancer [Internet]. 2018 [cited 2020 Aug 26]. Available from: https://www.who.int/en/news-room/fact-sheets/detail/cancer

5. Globocan 2018 Latest global cancer data – IARC [Internet]. Iarc.fr. 2018 [cited 2020 Aug 26]. Available from: https://www.iarc.fr/infographics/globocan-2018-latest-global-cancer-data/

6. Sushmi Dey. ‘1 in 10 Indians to get cancer in lifetime’ [Internet]. The Times of India. Times Of India; 2020 [cited 2020 Aug 26]. Available from: https://timesofindia.indiatimes.com/india/1-in-10-indians-to-get-cancer-in-lifetime/articleshow/73947229.cms

7. The Difference Between Normal and Cancer Cells - DrJockers.com [Internet]. DrJockers.com. 2016 [cited 2020 Aug 26]. Available from: https://drjockers.com/cancer-cells/

8. What is cancer? | World Cancer Day [Internet]. Worldcancerday.org. 2018 [cited 2020 Aug 26]. Available from: https://www.worldcancerday.org/what-cancer#whatiscancer

9. India Against Cancer [Internet]. India Against Cancer. 2017 [cited 2020 Aug 26]. Available from: http://cancerindia.org.in/cancer-statistics/#:~:text=Oral%20cancer%20is%20the%20most,New%20cases%20registered%3A%2092%2C011