Chapter 12 + 13: Cancer Epidemiology/Childhood and Adolescent Cancer

Cancer

Disease caused by uncontrolled cell growth, arises from complicated web of etiologies and carcinogens.

Etiology

Study of causes or origins of diseases.

Carcinogens

Substances that promote cancer development, i.e. lifestyle behaviors, lack of physical exercise, infection, environmental factors, occupational exposure, and medications.

Interacting Factors of Cancer

Weaker immune systems, detoxifying enzyme variation, hormone level differences, metabolic factors

Morbidity

Rate of disease occurrence in a population.

Mortality

Rate of death in a population.

Incidence Rates

Frequency of new cancer cases in a population.

Liver Cancer

Highest rate of death and incidence rate of all reported cancer sites

Developmental Plasticity

Organism's ability to organize physiologically or structurally in response to environmental conditions during fetal development

In Utero Exposure

Fetal exposure to substances affecting later health.

Developmental Origins' Hypothesis

Nutrition and other environmental factors affect cellular pathways during gestation, enabling a single genotype to produce a broad range of adult phenotypes (i.e maternal nutrition, environment)

Cigarette smoke

Carcinogenic, most important cause of cancer that causes it in over 15 organ sites.

Secondhand Smoke

Inhalation of smoke from others' tobacco use; can can stroke, inflammation, immunity impairment, and rheumatoid arthritis

Nutrigenomics

Study of nutrition's effects on on the phenotypic variability of individuals based on genomic differences.

Mediterranean dietary pattern

Dietary pattern promoting health and cancer prevention.

Cancer risk among migrants

With geographic migration, risks and cancer patterns change, particularly with the adoption of the Western diet.

Bioactive components

Food compounds influencing cancer stem cell differentiation.

Xenobiotics

Toxic chemicals that can cause cancer. Many foods enhance the efficiency and degree of detoxification, serving a protective role in metabolizing carcinogens.

Red meat

Diets high in this lead to increased risk of colorectal cancer due to preservatives left in the colon.

A physical factor that increases risk for 11 different types of cancer; a United States epidemic

Three mechanisms of of obesity-associated cancer risks

1.) Insulin-like growth factor (IGF-1) axis

2.) Sex hormones

3.) Adipokines (hormones released by adipose tissue)

Metabolic changes in adipose tissue

Insulin resistance, hyperglycemia, dyslipidemia, hypoxia, chronic inflammation

Alcohol-related carcinogenesis

Involves acetaldehyde, reactive oxygen species (ROS), pro-carcinogen activation, cellular regeneration, nutritional deficiencies, and enzyme/metabolic dysfunction

Biological mechanisms for the protective effects of physical activity

Decreases insulin and IGF levels, decreases oncogenes, and increasing free radical scavenger system

Exercise recommendations

150 minutes of moderate or 75 minutes of vigorous activity weekly.

Air pollution

Leading environmental cause of death globally.

Particulate Matter

Mixture of small particles and liquid droplets.

Primary Particles

Emitted directly from sources like construction sites or smokestacks.

Secondary Particles

Formed from emissions of power plants, industries, and automobiles.

Diesel Exhaust

Carcinogenic fumes linked to lung cancer, asthma attacks, and myocardial ischemia.

Mechanisms of Particulate Matter's Adverse Affects

1.) Oxidative stress

2.) ROS generation

3.) DNA oxidative damage

4.) Mutagenicity

5.) Stimulation of proinflammatory factors

6.) Induction of senescence

Oxidative Stress

Imbalance between free radicals and antioxidants.

Induction of Senescence

Cellular aging triggered by stressors.

Indoor Air Pollution

Worse than outdoor pollution, includes tobacco smoke.

Ionizing Radiation (IR)

Radiation that can cause cancer and mutations.

Life Span Study

Research on atomic bomb survivors' cancer effects.

ERRs

Excess relative risks for radiation-induced cancers.

Bimodal Age Distribution

Cancer risk varies by age at exposure-- Early ages is related to initiation of cancer processes, later ages are associated with promotion of pre-existing premalignant cells.

Mutagen

Substance that causes genetic mutations.

Affects of IR on DNA

Cross-linking, nucleotide base damage, single-double stranded DNA breaks.Double stranded break = Hallmark of IR instability.

Genomic Instability

Inherited mutations affecting future cell generations.

Ultraviolet Radiation (UVR)

Radiation from sunlight and artificial sources. Consists of UVA and UVB waves, with UVA being weaker but more penetrative.

Basal Cell Carcinoma (BCC)

Skin cancer linked to intense intermittent recreational sun exposure.

Squamous Cell Carcinoma (SCC)

Skin cancer associated with chronic sun exposure.

Melanoma

Severe skin cancer from intense sun exposure.

Skin cancer risk factors

Cumulative sun exposure, ionizing radiation, chronic arsenic ingestion, immunosuppression, genetic factors

Nonmelanoma Skin Cancers

Skin cancers excluding melanoma, often due to UV exposure.

Electromagnetic Radiation (EMR)

Energy from electric and magnetic waves.

Most common source of radio frequency electromagnetic radiation (RF-EMR)

Wireless communication devices

Low-Frequency EMFs

Classified as possible carcinogens by health agencies.

Most notable cancer-causing viruses

Epstein-Barr

Hepatitis B

Hepatitis C

Human Papillomavirus

Helicobacter Pylori

Bacteria causing 75% of stomach cancers.

Most common sexually transmitted virus in the U.S.

HPV

HPV Types 16 and 18

Responsible for most HPV-related cancers, identified as definite carcinogens

Cervical Intraepithelial Neoplasia

Precursor lesions for cervical cancer from HPV.

HPV Vaccine

Reduces cervical cancer risk but screening is still needed.

HPV and biological factors interaction

Smoking, decreased immunity, having many children, oral contraceptive use, chronic inflammation

Human Herpes Virus Type 8

Linked to Kaposi sarcoma development.

Human T-cell Lymphotropic Virus Type 1

Associated with leukemia and lymphoma.

Chemical Carcinogenesis

Cancer caused by genotoxic (genetic) and nongenotoxic (non-genetic) chemical mechanisms.

Asbestos

Linked to mesothelioma, banned in many countries.

Synthetic Chemicals

100,000 used in the US, few fully tested.

Childhood cancer

Rare disease, but is still the 2nd leading cause of death in children

Most common childhood cancer

Leukemia

Second most common type of childhood cancer

Brain/CNS tumors

Rarity of carcinomas in children

Children have not lived long enough for environmental exposures to cause tumor formation.

Down Syndrome

Syndrome that leads to increased risk of leukemia

Risk factors of childhood cancer

Gene/genomic changes, nutrition and diet, immune function, occupational exposure, hormones, viruses, environment

Goals of cancer treatment for children

Less toxic treatments with fewer long-term side effects.