Aging and Cancer: Intervention Strategies

Aging and Cancer: Intervention Strategies

Shailendra Prasad Verma (King George's Medical University, India) and Pooja Mahour (King George's Medical University, India)
Copyright: © 2018 |Pages: 17
DOI: 10.4018/978-1-5225-3480-8.ch013

Abstract

This chapter describes aging and the resultant effects of aging. According to WHO report 8.8 million people died from cancer worldwide in 2015. The incidence of cancers increases with age. This increase incidence may be due to biological factors, prolonged exposure to carcinogens and incidence of mutations etc. Cancers in elderly may have poor biological vulnerability, presence of various co-morbidities and poor tolerance of therapy hence treatment got compromised. Elderly cancer patients also are neglected in various trials and strong data lacks for optimal management. Other important aspect is psychosocial state of these patients. Discipline of Psycho-oncology deals with patients with cancer, their lifestyle related difficulties, negligence by self, family members and society, Lack of emotional support, poor financial assistance and treatment monitoring etc. leading to various psychological problems. This chapter will address issues of cancers in elderly including disease biology, disease characteristics, management, their quality of life etc. with reference to elderly patients suffering from cancer.
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Aging At Cellular And Molecular Level

Aging is a complex process many theories have evolved over a time period in quest of explanation to the aging process. None of the theories proposed till date could explain it in a holistic way. It is increasingly becoming apparent that the molecular and subcellular processes of aging are also relevant in cancer and tumorogenesis.

Genetics and Aging

Experiments have shown that there are defined genes in low evolutionary animals like yeast, nematodes and drosophila which affect the life span of these organisms (Orr et al., 1994; Sun et al., 1994). Probably certain critical genes also relate to aging and life span in humans. Genetic regulation of aging comes from analysis of clinical syndromes with accelerated aging like progeria. Accelerated aging is seen in early onset progeria, late onset progeria and Down syndrome (Yu et al., 1996). Identification of genes in these patients is at least a beginning towards understanding of molecular mechanisms involved in aging process. Werner syndrome is a disease of adolescent onset characterised by short stature and probability of development of cancers of mesenchymal origin. Yu et al. (1996) published a data on etiology of Werner syndrome caused by mutation in a single gene located on human chromosome 8 that encodes a helicase –like protein (Yu et al.,1997). Functional characterisations of these genes may be of great significance in understanding physiology of aging.

Telomere Biology and Aging

Cells have their genetic code in form of DNA which is a part of the chromosome. Telomeres are part of our chromosomes which cap their terminal ends and protect chromosomes from damage. With each cell division the telomere gets shortened. Ultimately it comes to a critical level where cell senescence occurs and cell dies. This process gives a defined life span to an individual. Telomerase is an enzyme which tries to protect the telomeres from shortening (Harley & Villeponteau, 1995). During this process cancers can arise due to chromosomal instability. If telomere shortening can be prevented life can be extended which is area of current research too. Many cells of our body like stem cells, sperm cells and T lymphocytes have high replicative power and express telomerase.

There is evidence that many key genes may be involved in maintenance of telomeres. TERC (Telomere RNA complex gene) and TERT (Telomere reverse transcriptase gene) mutations have been implicated in rapid shortening of telomeres in inherited and acquired aplastic anaemia, a process where bone marrow fails producing hematopoietic stem cells. Dyskeratosiscongenita (DKC) is an inherited bone marrow failure syndrome characterized by extremely short telomeres. It has X- linked, autosomal recessive and autosomal dominant patterns of inheritance. Mutation in a gene called DKC1 which codes dyskerin protein is responsible for X-linked type of DKC. Autosomal dominant type of DKC is associated with mutation in TERC gene. This syndrome presents with bone marrow failure (cytopenias), dystrophic nails and skin changes. Patients with DKC are at increased risk myelodysplastic syndrome, leukemia, primarily acute myeloid leukemia and squamous cell carcinomas. This is a classic example of a group of relatively recententity i.e. telomeropathy (Dokal, 2000).

Key Terms in this Chapter

Malignant Hematological Disorders: Refers to cancers of hematological origin like lymphomas and leukemias.

Tumour Aggressiveness: Describes a tumor or disease that forms, grows, or spreads quickly usually associated with adverse biological and clinical features without intense chemotherapy.

Cell Cycle: Cell Cycle is a highly regulated process of events occurring inside the cell leading to cell division (mitosis) and formation of new cells.

Angiogenesis: Angiogenesis is formation of new blood vessels usually mediated by some chemicals in body.

Stem Cells: An undifferentiated cell of a multicellular organism which is capable of giving rise to indefinitely more cells of the same type, and from which certain other kinds of cell arise by differentiation.

Psychological Management in Cancer: Taking care of psychological aspects of treatment of cancer. Emotional and social support can help patients learn to cope with psychological stress. Such support can reduce levels of depression, anxiety, and disease- and treatment-related symptoms among patients.

Quality of Life: The standard of health, comfort, and happiness experienced by an individual or group.

Resistance Cytogenetic: Adverse cytogenetic abnormalities leading to poor response to chemotherapy.

DNA Repair Defect: A limited number of rare hereditary diseases characterized by genetic defect of DNA repair mechanisms is known as DNA repair defect for example: comprising ataxia telangiectasia, Nijmegen breakage syndrome, Werner syndrome, Bloom Syndrome, Fanconianemia, xerodermapigmentosum.

Cellular Senescence: Generally defined as an irreversible state of G1 cell cycle arrest in which cells are refractory to growth factor stimulation.

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