2. Learning Objectives
• Describe cancer disease
• Risk of tobacco on cancer
• Risk of ultraviolet radiation on cancer.
• Chemoprevention efficacy
• Vaccine prevention against cancer
• Stages of cancer
• Principles of Tumor Growth
• Methods of cancer spread
3. Cancer Disease
➢Cancer disease is the condition that describes the
uncontrolled cells growing which has the potential
for invading local tissue and spreading to other
parts of the body (metastases).
➢ Cancer is the second leading cause of death behind
heart disease in US.
➢Today, most patients are able to receive
chemotherapy in the outpatient clinics or take oral
anticancer agents at home.
➢Most cancers are not curable in advanced stages
4. Cancer prevention
• Because most cancers are not curable in advanced stages, cancer prevention is an
important and active area of research.
The risk factors of cancer can be reduced by:
• Lifestyle modifications
• Chemoprevention agents
• Vaccines
6. Tobacco
Tobacco smoking increases the risk of developing of the
following cancers:
• Lung cancer
• Bladder cancer
• Mouth cancer
• Pharynx cancer
• Larynx cancer
• Esophagus cancer
• Kidney cancer
Smoking cessation is associated with a gradual decrease in the
risk of cancer, but more than 5 years is needed before a major
decline in risk is detected.
7. Ultraviolet (UV) Radiation
➢Ultraviolet lights increase the risk of skin cancers (sunlight or tanning booths and lamps)
➢Melanoma, the most serious type of skin cancer, develops in the cells (melanocytes) that produce melanin.
The risk increased with individuals who have
➢A positive family history
➢Fair skin
➢Light colored eyes
➢High degrees of freckling
➢Tendency to burn instead of tan.
8.
9. The proper UV protection methods, include the following:
➢Minimizing sun exposure
➢Using sunscreens with a sun protection
factor (SPF) of 15 or greater on exposed
areas
➢Wearing protective clothing and sunglasses
➢Avoiding tanning beds and sun lamps
11. ➢Selective estrogen receptor modulator (SERM) tamoxifen, reduces the risk
of breast cancer in premenopausal women.
➢Another SERM, raloxifene and the aromatase inhibitor (AI) exemestane
both have shown a reduction in breast cancer in high-risk postmenopausal
women.
12. Environmental Chemical carcinogenic agents
Chemicals in the environment, such as aniline and benzene, are associated
with bladder cancer and leukemia.
• The majority of aniline released from industries and natural forest fires.
• Natural sources of benzene include volcanoes and forest fires.
• Benzene is also a natural part of crude oil, gasoline, and cigarette smoke
14. ➢Vaccines that prevent infection with human papillomavirus (HPV)
- HPV responsible for many cancers of the cervix, vulva, vagina, and anus
➢Vaccine that prevents hepatitis B viral infections
- Hepatitis B viral infections can cause liver cancer.
15. HPV infections
➢HPV infections can cause certain cancers in men and women
➢HPV is thought to be responsible for more than 90% of anal
and cervical cancers, about 70% of vaginal and
vulvar cancers, and 60% of penile cancers.
➢HPV spreads easily through skin-to-skin contact
➢Prolonged contact with infected skin, such as holding hands,
may cause transmission of the virus.
16. Stages of cancer
• There are four stages in the cancer development process.
• The first step (Initiation) occurs when a carcinogenic substance produce genetic damage and
results in a mutated cell.
• The Second step (Promotion): alters the growth of the mutated cell
17. Stages of cancer
• The Third step (Transformation or conversion) occurs when the mutated
cell becomes malignant.
• The Fourth step (Progression) occurs when cell proliferation takes over
and the tumor spreads or develops metastases.
18.
19. Genetics in cancer
Two major classes of genes when mutated are involved in carcinogenesis:
1- Protooncogenes
2- Tumor suppressor genes
3- DNA repair genes
✓Protooncogenes are normal genes that change into oncogenes.
✓They present in all normal cells and regulate cell function and replication.
20. Oncogenes
The factors that increase the genetic damage of the protooncogene are:
• Chromosomal rearrangement
• Mutation
• The increase in gene function
The oncogene produces abnormal product that disrupts normal cell growth and
proliferation which increasing the risk of becoming cancerous.
21. Tumor suppressor genes
Tumor suppressor genes inhibit inappropriate cellular growth and proliferation which results in loss
of control over normal
➢The TP53 gene is one of the most common tumor suppressor genes, and mutations of TP53 may
occur in up to 50% of all malignancies
➢The mutations of the TP53 gene are found in many tumors, such as breast, colon, and lung cancer.
22. Deoxyribonucleic acid (DNA) repair genes
➢Deoxyribonucleic acid (DNA) repair genes fix errors in DNA that occur because of
environmental factors or errors in replication and can be classified as tumor suppressor
genes.
➢Mutations in DNA repair genes have been reported in hereditary colon cancer and in some
breast cancer syndromes
23. Principles of Tumor Growth
➢It takes about 109 cancer cells to be clinically detectable by palpation or
radiography.
➢Malignant cell growth occurs many times before a mass may be detected.
➢The number of malignant cells may decrease drastically because of surgery or
by each administration of chemotherapy.
24. Metastasis
A metastasis is a growth of the same cancer cell found at some distance from the primary
tumor site.
✓The metastasis may be large, or it may be just a few cells that may be detected through
polymerase chain reaction (PCR).
✓The presence of metastasis at diagnosis usually is associated with a poorer prognosis than
the patient with no known metastatic disease.
25. Methods of cancer spread
1-Hematogenous (through the bloodstream)
2-Through the lymphatics (drainage through adjacent lymph nodes).
✓The usual metastatic sites for solid tumors are the brain, bone, lung, and liver.
