Copyright (c) by W. H. Freeman and Company 25-5 Cancer Copyright (c) by W. H. Freeman and Company

Copyright (c) by W. H. Freeman and Company What is cancer? Cancer is defined as the continuous uncontrolled growth of cells. A tumor is a any abnormal proliferation of cells. Benign tumors stays confined to its original location Malignant tumors are capable of invading surrounding tissue or invading the entire body Tumors are classified as to their cell type Tumors can arise from any cell type in the body Copyright (c) by W. H. Freeman and Company

Copyright (c) by W. H. Freeman and Company Cancer is an umbrella term covering a numerous conditions characterized by unscheduled and uncontrolled cellular proliferation Almost any mammalian organ and cell type can succumb to cancer The causes of cancer are many and varied, and include genetics, environmental influences, infectious agents and ageing. These transform normal cells into cancerous ones The complexity of the disease that has hampered the development of effective and specific cancer therapies. Copyright (c) by W. H. Freeman and Company

Copyright (c) by W. H. Freeman and Company Cancer cells have abnormal cell cycles divide excessively and form tumors Copyright (c) by W. H. Freeman and Company

Copyright (c) by W. H. Freeman and Company Breast cancer cell - altered morphology Figure 8.10x1 Copyright (c) by W. H. Freeman and Company

Copyright (c) by W. H. Freeman and Company A kidney tumour A kidney carcinoma (the blob at the top) Copyright (c) by W. H. Freeman and Company

Copyright (c) by W. H. Freeman and Company Lung Cancer x-ray Squamous carcinoma Copyright (c) by W. H. Freeman and Company

Copyright (c) by W. H. Freeman and Company Colon Cancer X-ray Gross Microscopic Copyright (c) by W. H. Freeman and Company

Heterogeneous size and shape of cancer cells and cancer cell nuclei Heterogeneous size and shape of cancer cells and cancer cell nuclei. The nuclear heterogeneity reflects the genetic instability. Copyright (c) by W. H. Freeman and Company

Cancer continued 3 cancer types Carcinomas; constitute 90% of cancers, are cancers of epithelial cells Sarcomas; are rare and consist of tumors of connective tissues (connective tissue, muscle, bone etc.) Leukemias and lymphomas; constitute 8% of tumors. Sometimes referred to as liquid tumors. Leukemias arise from blood forming cells and lymphomas arise from cells of the immune system (T and B cells). Copyright (c) by W. H. Freeman and Company

Properties of cancer cells Normal cells show contact inhibition Cancer cells lack contact inhibition Copyright (c) by W. H. Freeman and Company

Properties of cancer cells They keep growing And growing Copyright (c) by W. H. Freeman and Company

Cancer Incidence and Death Rates Copyright (c) by W. H. Freeman and Company

Copyright (c) by W. H. Freeman and Company Cancer Cells in culture and in vivo exhibit contact-inhibition Cancer cells lack contact inhibition feedback mechanisms. Clumps or foci develop. Copyright (c) by W. H. Freeman and Company

Copyright (c) by W. H. Freeman and Company Cancer Grade Alternate term “tumor grade” Based on microscopic features (cytology or histology) low grade moderate high Copyright (c) by W. H. Freeman and Company

Early detection is the key! Copyright (c) by W. H. Freeman and Company

What causes Cancer? Genetic mutations Copyright (c) by W. H. Freeman and Company

What is the source of oncogenes? Mutation of a normal gene = change in DNA sequence UV light, Xrays, natural or synthetic chemicals Virus (ex. HPV and cervical cancer) Copyright (c) by W. H. Freeman and Company

How do normal cells become cancerous? Selection within tumor for “most cancerous” cells Copyright (c) by W. H. Freeman and Company

Copyright (c) by W. H. Freeman and Company

Copyright (c) by W. H. Freeman and Company Cancer: Benign Benign: localized and of small size Cells that closely resemble, and may function, like normal cells May have a fibrous capsule around the cells Become problems due to sheer bulk or due to secretions (e.g. hormones) Copyright (c) by W. H. Freeman and Company

Copyright (c) by W. H. Freeman and Company Cancer : Malignant Malignant tumors: high rate of division, properties may vary compared to cells of origin. Most malignant cells become metastatic Invade surrounding tissue and establishment of secondary areas of growth: Metastasis Copyright (c) by W. H. Freeman and Company

Copyright (c) by W. H. Freeman and Company Malignant tumors can invade other tissues and may kill the organism Lymph vessels Tumor Glandular tissue Metastasis 1 A tumor grows from a single cancer cell. 2 Cancer cells invade neighboring tissue. 3 Cancer cells spread through lymph and blood vessels to other parts of the body. Figure 8.10 Copyright (c) by W. H. Freeman and Company

Copyright (c) by W. H. Freeman and Company Growth pattern Benign Malignant Copyright (c) by W. H. Freeman and Company

Metastasis Carcinoma: derived from endoderm or ectoderm Copyright (c) by W. H. Freeman and Company

Copyright (c) by W. H. Freeman and Company Events in Metastasis. Copyright (c) by W. H. Freeman and Company

Copyright (c) by W. H. Freeman and Company Angiogenesis Cancer cells block the formation of new blood vessels that bring necessary nutrients and oxygen to the hungry tumor cells This forms a network of new blood vessels! Copyright (c) by W. H. Freeman and Company

Copyright (c) by W. H. Freeman and Company 24.1 Benign tumors arise with great frequency but pose little risk because they are localized and small Figure 24-1 Copyright (c) by W. H. Freeman and Company

Copyright (c) by W. H. Freeman and Company 24.1 Malignant tumors generally invade surrounding tissue and spread throughout the body Alterations in cell-cell interactions and the formation of new blood vessels are associated with malignancy Figure 24-2 Copyright (c) by W. H. Freeman and Company

DNA from tumor cells can transform normal cultured cells transformed Cells that continue to grow when normal cells have stopped are said to be transformed Transformed cells may exhibit many of the properties of malignant tumor cells Copyright (c) by W. H. Freeman and Company Figure 24-3