Cell Biology and Cancer

What is cancer?

• In simple terms, cancer is a group of more than 100 diseases that develop across time and involve the uncontrolled division of the body’s cells.

• Cancer begins when a cell breaks free from the normal restraints on cell division and begins to follow its own agenda for proliferation (multiply).

What is a tumor?

• A tumor is a mass of cells.• In situ cancer- means the

abnormal cells remain within the tissue in which it originated.

• Invasive cancer- when the abnormal cells begin to invade nearby tissues.

Malignant

• An invasive tumor is said to be malignant. The cells shed in to the blood or lymph from a malignant tumor.

• This likely establishes new tumors throughout the body, also known as metastases.

• Tumors threaten an individual's life when the growth disrupts the tissues and organs.

3 stages of tumor development

Cell with genetic mutation, hyperplasia, dysplasia, in situ cancer, invasive cancer.

Research• Over the last 3 decades, research

has revolutionized our understanding of cancer.

• Largely due to the application of the techniques of molecular biology.

• Today we know cancer is a disease of molecules and genes

• Our increasing understanding of these genes makes it possible for development of new strategies for preventing, forestalling and even correcting the changes that lead to cancer.

Clues from epidemiology

• In 1775, a high incidence of scrotal cancer was described among men who worked as chimney sweepers.

• In the mid-1800’s, lung cancer was observed at alarmingly high rates among miners in Germany.

• At the end of the 19th century, using snuff and cigars was thought to be closely associated with cancers of the mouth and throat.

• These observations and others suggested that the origin or causes of cancer may lie outside the body, and more importantly, they could be linked to identifiable and even preventable causes.

• These ideas led to a widespread search for agents that might cause cancer.

• An early notion, prompted by the discovery that bacteria caused a variety of human diseases, suggested cancer was an infectious disease.

• Another idea was that cancer arises from chronic irritation of tissues.

• This view received strong support with the discovery of X-rays in 1895 and the observation that exposure to this form of radiation could induce localized tissue damage, which could lead in turn to the development of cancer.

• Another view is that it is hereditary.

• In 1910, a submicroscopic agent was isolated from a chicken tumor and found that it could induce new tumors in healthy chickens.

• This theory led scientists to find out that an agent known as the Rous Sarcoma virus is one of several viruses that can act as a causative factor in the development of cancer.

Clues from cell biology

• Cancer cells are indigenous cells—abnormal cells that arise from the body’s normal tissues.

• All malignant tumors are monoclonal in origin (cells are derived from a single clone).

Development of cancer

• The development of cancer occurs as a result of a series of clonal expansions from a single ancestral cell.

• Although a tumor is monoclonal, it may contain a large number of cells with diverse characteristics.

Normal cells vs. cancerous cells

• Cancerous cells look and act differently from normal cells.

• In normal cells, the nucleus is only 1/5th the size of the cell.

• In cancerous cells, the nucleus may occupy most of the cells volume.

• Tumor cells have lost their restraints on growth that characterize normal cells.

Cancer Trends Progress Report (CTPR) - 2007

Update• MeasureTrendPREVENTION• Age at smoking initiationStable• Youth smokingFalling• Adult smokingFalling• Quitting smokingStable• Health professional advice to quit smokingFalling• Secondhand smokeEnvironmental Tobacco

Smoke NSC• Smoke-free work environment Rising• Smoke-free indoor air lawsRising• Fruit & vegetable consumptionNSC• Red meat consumption Stable

• Fat consumption Stable• Alcohol consumptionRising• Weight (both sexes)  Healthy weight

NSC• OverweightStable• ObeseNSC• No leisure time physical activityNSC• Sun protectionFalling• Pesticide levels in the bloodRising• Dioxin levels in the human body

Falling

• Breast cancer screeningFalling • Cervical cancer screeningFalling• Colorectal cancer screeningFecal

Occult Blood Test (FOBT)Falling• EndoscopyRising• Colorectal test useRising

EARLY DETECTION

DIAGNOSIS Incidence• All cancersFalling• WhiteFalling• BlackFalling• HispanicsFalling• American Indian/Alaskan Natives

NSC• Asian/Pacific IslandersFalling

Four most common cancers

• ProstateStable• Female breastFalling• ColorectalFalling• Lung and bronchusFalling

Cancers that are increasing

• Non-Hodgkin lymphomaRising• Melanoma of skin (White only)RisingStage at diagnosisColonFallingFemale breastStableRectumFallingCervixNSCProstateFalling

Breast cancer treatment

• MastectomyFalling• No surgeryRising• BCS with radiationNSC• BCS without radiationRising• Multiagent chemotherapyRisingColorectal cancer treatmentRising

Life after cancer

• Survival:• All cancersRising• ProstateRising• Female breastRising• ColorectalRising• Lung and bronchusRising

End of life (all cancers)

• All cancersFalling• WhiteFalling• BlackFalling• HispanicFalling• American Indian/Alaskan Natives

Stable• Asian/Pacific IslanderFalling

Mortality of the 4 main cancers

• ProstateFalling• Female breastFalling• ColorectalFalling• Lung and bronchusFalling