Cancer is characterized by uncontrolled cell growth and can affect many parts of the body. In New Zealand, cancer is a leading cause of death, with the most common cancers being lung, prostate, colorectal, breast and lung cancers. Maori have higher mortality rates from cancer compared to non-Maori. Cancers are caused by defects in cellular proliferation and differentiation as well as environmental and genetic factors. Cancer cells spread via metastasis which can occur early for some cancers or later for others. The immune system plays a role in detecting cancer cells but cancers can evade immune response.

1. Cancer

2. Introduction A group of more than 200 diseases characterized by uncontrolled and unregulated growth of cells In NZ 14,808 new cases of cancer 1 in 3 men and 1 in 4 women will be affected by age 75yrs Most common cause of death in NZ (29% of deaths overall)

3. Cancer Most common cancers causing death in males are lung, prostate and colorectal Most common cancers causing death in females are breast, lung & colorectal Cancer rates for Maori & non Maori are similar but mortality rates are 51% (males) and 78%(females) higher for Maori

4. 5-year survival rate is now 62% for those who are disease free, in remission, or under treatment 5-year survival rates do not include the number of people who are “cured” of cancer

5. Defect in Cellular Proliferation (process by which cells divide & reproduce) Cancer cells are characterized by the loss of contact inhibition – have no regard for cellular boundaries Grow on top of one another and on top of or between normal cells Cancer cells divide indiscriminately and haphazardly – sometimes they produce more than 2 cells at the time of mitosis

6. Defect in Cell Proliferation In most situations, cancer cells multiply at the same rate as the normal cells from which they originate The difference is that proliferation of the cancer cells is indiscriminate and continuous Because of this there is continuous growth of a tumour mass

7. Defect in Cellular Differentiation Cellular differentiation (the development of specific & distinctive features in cells) is normally an orderly process Protooncogenes Normal cellular genes that are important regulators on normal cellular processes Mutations that alter their expression can activate them to act as oncogenes (tumour-inducing)

8. Neoplasms Characterised as: Benign neoplasms Malignant neoplasms Major difference between malignant & benign neoplasms is the ability of malignant tumour cells to invade and metastasize

9. Benign Neoplasms Well differentiated (specific & distinctive features of cells are well developed). Cells resemble the cells of tissue of origin. Well-defined fibrous capsule Characterized by slow, progressive rate of growth. Tumours grow by expansion Metastases absent Recurrence unusual Do not usually cause death unless they interfere with vital functions because of location e.g.. Benign cranial tumour compressing brain structures

10. Malignant Neoplasms Tend to grow rapidly, spread widely, & kill regardless of original location Able to metastasize Because of rapid growth, they compress blood vessels & outgrow their blood supply causing ischaemia & tissue necrosis Rob normal tissues of essential nutrients Liberate enzymes & toxins that destroy normal & tumour tissue Infiltrative and expansive Frequent recurrence Moderate to marked vascularity Rarely encapsulated Cells abnormal; become more unlike parent cells

11. Effects on Body Function with Cancer Growth Altered function of involved tissue Bleeding & haemorrhage Ulceration, necrosis & infection of tumour area Obstruction of hollow organs or pathways Effusion in serous cavities Increased risk of vascular thrombosis Anaemia Bone destruction

12. Effects (cont.) Hypercalcaemia Pain Cachexia – weight loss & wasting of body fat & lean protein Inappropriate hormone production (e.g. ADH or ACTH secretion by cancers such as bronchogenic carcinaoma)

13. Cachexia

14. Advanced Breast Cancer

15. Cancer of Kidney

16. Ascites – Liver Cancer

17. Development of Cancer Carcinogens – cancer-causing agents capable of producing cellular alterations Can be chemical, environmental, immunologic, viral, or spontaneous in origin Some genetic abnormalities increase the susceptibility of individuals to certain cancers Hereditary predisposition in approx 50 types of cancers e.g. breast cancer

18. Process of Cancer Development Fig. 15-3

19. Metastasis The spread of cancer from the initial or primary site to a distant site Some metastasize early e.g. pre-menopausal breast cancer Others spread regionally and rarely metastasize e.g.. BCC of skin Certain cancers have an affinity for a particular tissue or organ as a site of metastasis, others are unpredictable e.g. melanoma

20. Metastasis (cont.) Certain cancers (‘seed’), such as ovarian cancer, require a particular site for proliferation (‘soil’) Most frequent sites for metastases are lungs, brain, , bone, liver & adrenals

21. Metastasis Metastasis process begins with rapid growth of primary tumour Development of its own blood supply is critical for survival Tumour angiogenesis is formation of blood vessels within the tumour

22. Melanoma Metastases

23. Progression of Cancer Metatases

25. Role of Immune System Immune response is to reject or destroy cancer cells if perceived as non-self May be inadequate as cancer cells arise from normal human cells Some cancer cells have changes on their surface antigens Tumor-associated antigens (TAAs)

26. Role of Immune System Response to TAAs is termed immunologic surveillance Lymphocytes continually check cell surfaces and detect and destroy cells with abnormalities Involves cytotoxic T cell, natural killer cells, macrophages, and B lymphocytes

27. Role of Immune System Escape mechanisms by which cancer cells evade immune system Suppression of factors that stimulate T cells Weak surface antigens allow cancer cells to “sneak through” surveillance

28. Role of Immune System Development of tolerance of immune system Suppression of immune response to products secreted by cancer cells Induction of suppressor T cells Blocking antibodies that bind TAAs

29. Classification of Cancer Anatomic Site Classification Identified by tissue origin anatomic site behaviour of the tumour

30. Classification of Cancer Anatomic Site Classification Carcinomas originate from embryonal ectoderm and endoderm Sarcomas originate from embryonic mesoderm Lymphomas and leukaemias originate from hepatopoietic system

31. Classification of Cancer Histologic Analysis Classification Appearance of cells and degree of differentiation are evaluated Grade 1: Cells differ slightly from normal cells and are well differentiated Grade 2: Cells more abnormal and moderately differentiated

32. Classification of Cancer Grade 3: Cells very abnormal and poorly differentiated Grade 4: Cells immature and primitive and undifferentiated; cell of origin difficult to determine

33. Classification of Cancer Clinical Staging 0: cancer in situ 1: tumor limited to tissue of origin 2: limited local spread 3: extensive local and regional spread 4: metastasis

34. Classification of Cancer TNM Classification Tumor size Spread to lymph nodes Metastasis

35. TNM Classification System T (tumour) Tx Tumour unable to be adequately assessed T0 No evidence of primary tumour Tis Carcinoma in situ T1-4 Progressive increase in tumour size or involvement

36. TNM Classification System N (nodes ) Nx Regional lymph nodes cannot be assessed N0 No evidence of regional node metastasis N1-3 Increasing involvement of regional lymph nodes

37. TNM Classification System M (metastasis) Mx Not assessed M0 No distant metastasis M1 Distant metastasis present, specify sites

38. Prevention and Detection of Cancer Reduce or avoid exposure to known or suspected carcinogens Eat balanced diet Exercise regularly Adequate rest Health examination on a regular basis

39. Prevention and Detection of Cancer Eliminate, reduce, or change perceptions of stressors and enhance ability to cope Enjoy consistent periods of relaxation and leisure Know 7 warning signs of cancer Self-examination Seek medical care if cancer is suspected

40. Early Warning Signs of Cancer Change in bowel or bladder habits A sore that does not heal Unusual bleeding or discharge Thickening or lump in breast or elsewhere Indigestion or difficulty in swallowing Obvious change in mole or wart Nagging cough or hoarseness