Cancer Biology

Topics: Cancer, DNA, Gene expression Pages: 39 (9712 words) Published: September 10, 2012
Cancer Epidemiology

Cancer is not a single disease; it is a myriad or collection of diseases with many different manifestations as there are many different types of tissues and cell types Cancer is a disease of abnormal gene expression.

Cells are constantly evolving and have the natural selection pressures to change

Common biological properties of tumor cells:
1) Deregulated clonal cell growth- all cells in a tumor originated from one single cell that acquired mutations that made it deregulated cancer cells are constantly testing different mutations so they are constantly changing

2) Impaired cellular differentiation - cancer cells have lost the ability to differentiate. Cells stop growing once they differentiate so cancer cells can't differentiate therefore they keep growing

3) Invasiveness -benign tumor are localized and encapsulated, malignant tumors invade surrounding areas

4) Metastatic potential- not only have they become invasive but they have spread to secondary or distal sites

Cancer cells become deprogrammed

Proto-oncogenes encode for positive mediators of cell proliferation and growth. They drive the proliferation of the cell ex: growth factor receptor

Tumor suppressor gene encode negative growth regulatory factors. They counter the effects of protooncogenes. In cancer cells they bypass the negative effects of these so they continue to grow

Cancer epidemiology is the study of distribution of various cancer types among world populations with consideration of specific risk factors and etiologic agents involved in disease causation such as age, ethnicity or even exposure to carcinogens Cancer epidemiology is the study of cancer instance, mortality, risk factors, and attempting to relate and find causation A carcinogen does not necessarily cause cancer but it can cause a progression of the disease such as a benign tumor becoming malignant

Any abnormal growth is cancer there is just a difference between malignant and benign. Neoplasticism disease is another name for cancer

Cancer rates are closely tied with the rate of detection because a high incidence rate can lead to low mortality because if you find it first you can treat it easier

We study cancer epidemiology in order to monitor long range trends in cancer incidence to investigate cancer etiology

The average age at the time of cancer diagnosis for all tumor sites is 67 years old Cancer is associated with the aging process because DNA repair mechanisms break down leading to more mutations in DNA leading to possible degradation of cell regulation As a higher percentage of the population reaches 60, the incidence of cancer increases proportionally Additionally, as life expectancy of populations increase, due to a reduction in other causes of premature death, the average risk of cancer increases.

Cancer Statistics:
The biggest cancers involves reproductive organs, digestive system, respiratory system and breast cancers. Reproductive has highest incidence
Respiratory cancers are most deathly, then digestive then reproductive Respiratory cancer is most deathly in females

There is an equal distribution of male and female cancers
Skin cancers are the most common
Basal and squamous cell carcinomas (SCCS)

Types of Cancers:
Reproductive cancers are prostate, cervical, ovary, uterine
Digestive cancers are colon, rectum, pancreas, stomach, liver and esophagus Respiratory cancers include lung and bronchus
Digestive and respiratory cancers are deep tissue cancers so hard to detect early

Males are at the greatest risk of prostate then respiratory system then digestive system cancers. Prostate cancer has highest incidence rate with men
The mortality rates for prostate and colorectal cancers have remained relatively unchanged. Women are at the greatest risk of breast then respiratory system then digestive system cancers. Breast cancers have high rate of reoccurrence

Respiratory is...
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