CANCER A. THE NATURE OF CANCER def - sudden uncontrolled growth of cells

1. FEEDS ON THE BODY’S NUTRIENTS RESULTS FROM ANGIOGENESIS - FORMATION OF NEW BLOOD VESSELS

2. DEPLETES BODY’S SUPPLY OF NUTRIENTS  AMINO ACIDS, GLUCOSE, FATTY ACIDS

3. BLOCKS PASSAGEWAY FOR MATERIAL FLOW

4. DISRUPTS, OR PREVENTS PROTEIN SYNTHESIS

5. SECRETE PROTEASES  LEADS TO METASTASIS

6. BLOCKS DIFFERENTIATION  CELLS PRODUCED LACK SPECIALIZATION, THEIR FUNCTION IS THEREFORE INHIBITED

7. NO CONTACT INHIBITION  LEADS TO METASTASIS  CELLS MOVE OVER UNDER AND THROUGH NEIGHBORING CELLS

8. LACK ANCHORAGE DEPENDENCY  CELLS FLOAT FREELY  CELLS DO NOT REMAIN AT ORIGINAL SITE  LEADS TO METASTASIS

9. GENETIC INSTABILITY  HIGH MUTATION RATE  LEADS TO DRUG RESISTANCE  CONTAIN GENETIC ABBERRATIONS

10. GROWTH FACTOR REQUIREMENTS ARE LOW  RECEPTORS TO REGULATE GROWTH MALFUNCTION  IT DOESN’T REQUIRE MUCH TO INITIATE GROWTH

B. POSSIBLE CONTRIBUTING FACTORS  1. GENETIC PREDISPOSITION  2. CARCINOGENS  3. DIET  4. RADIATION  5. VIRUSES

C. MOLECULAR LEVEL  1. ONCOGENES – GENES THAT TRIGGER RAPID CELL DIVISION  (GAS PEDAL)  FORM WHEN PROTO-ONCOGENES MUTATE TO FORM ONCOGENES

discovery  discovered because of a viral link to some cancers and also from the ability to transfer genes from cancer cells to normal cells resulting in cancerous growth in the previously normal cells. THIS IS KNOWN AS TRANSFORMATION

2. TUMOR SUPPRESSOR GENES  GENES THAT SUPPRESS CELL GROWTH, KEEP IT IN CHECK

discovery -  from the fusion of a normal cell with a cancer cell resulting in no cancer activity  ex. - retinoblastoma - arises from a deletion of a gene on chromosome #13

p53 gene  tumor suppressor gene  found on chromosome #17  plays a role in lung, breast, colon/rectal cancers some leukemias and lymphomas - about 1 out of 3 cancers

3. DNA REPAIR GENES  OVER 130 HAVE BEEN IDENTIFIED  MAY BE INVOLVED IN MANY KINDS  OF CANCERS  XERODERMA PIGMENTOSUM

E. RESULTS  1. GROWTH SURROUNDED BY A MEMBRANE  2. ANGIOGENESIS  3. ENZYMES RELEASED BY CANCER CELLS DISSOLVE THE MEMBRANE  4. CANCER METASTASIZES

 5. CANCEROUS GROWTHS SPRING UP ELSEWHERE

F. HOW CANCER ELUDES THE IMMUNE SYSTEM  1. CANCER CELLS ARE SELF CELLS, SOMETIMES THE CHANGE IN SURFACE PROTEINS IS SO SLIGHT THAT IT GOES UNNOTICED

 2. THEY CAN EMIT DECOY ANTIGENS INTO THE BLOODSTREAM IN HIGH NUMBERS, AS ANTIBODY BINDS TO DECOYS, TUMOR GOES UNNOTICED

 3. NON COMPLEMENT BINDING ANTIBODIES SURROUND BUT DO NOT HARM THE TUMOR

 4. PIECE OF TUMOR BREAKS OFF - CLUMP IS DESTROYED, IMMUNE SYSTEM’s RESPONSE FOCUSED ON THE CLUMP, TUMOR REMAINS - A STATE OF SUPPRESSION OCCURS

 5. ANTI-ANTIBODIES SHUT DOWN AN ATTACK, ALONG WITH T SUPPRESSOR CELLS

G. PREVENTION  1. HABITS  smoking  excessive alcohol consumption  excessive exposure to the sun  diet (low fat, high fiber, low in pickled, smoked, cured foods

2. POSSIBLE POSITIVE ACTIONS  intake of vitamins A, C, D,E  beta carotene  calcium  avoid exposure to carcinogens, radiation, sunlight

H. WARNING SIGNS  CHANGE IN BOWEL/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 wart or mole  Nagging cough or hoarseness

I. EARLY DETECTION/SCREENING  PAP SMEAR - cervical carcinoma  Breast/testicular self exam  Prostate/ colon-rectal exams  Mammography  Annual exams  Ames Test – for carcinogenicity

 SOME CANCERS CANNOT BE OR ARE NOW DIFFICULT TO DETECT AT EARLY STAGES – ESPECIALLY LUNG CANCERS

J. TREATMENTS  1. SURGERY  2. RADIATION  3. CHEMOTHERAPY  4. IMMUNOTHERAPY-active – ex cancer vaccines and passive -ex monoclonal antibodies

 5. PROTON THERAPIES – easier to aim, cancer cells poor at repair  6. ANGIOSTATIC DRUGS  7. GENE THERAPY  8. BONE MARROW TRANSPLANTATION  9. HORMONE THERAPY – tamoxifen to block estrogen receptors in breast cancer

 10. COMBINATION THERAPIES  11. HIGH INTENSITY THERAPIES 12. PHOTODYNAMIC THERAPY – photosensitizing agent injected, remains in cancer cells longer, 2-3 d later exposed to light

13. TARGETED THERAPIES - Enzyme inhibitors - Apoptosis inducing drugs - gleevec

FUTURE?  GENE THERAPY? PROBLEM OF DELIVERY  MORE TARGETED APPROACHES  CLASSIFY CANCER ACCORDING TO THE MUTATION, NOT THE LOCATION

Go to the following web site:   Look up cancer – diagnosis and treatment