Molecular BIology of Cancer Topics
Cancer is a disease of malignant cell growth. A malignant tumor is an inheritably altered, relatively autonomous growth of tissue which ultimately invades and interferes with the function of normal tissues. It is capable of both invasion of surrounding tissue and metastasis to distant sites. Cancer can be fatal because a tumor will interfere with normal function of tissues.
A tumor is heritably altered because the DNA mutation required for the tumor to develop are passed on to daughter cells. The autonomous growth of a tumor is due to its insensibility to normal growth control mechanisms. Invasion refers to the tumor's ability to start additional malignant tumors beyond the boundaries of the original growth.
Transformation from a normal to a malignant epithelial tissue requires initiation, hyperplasia, invasiveness and metastasis. When a cell becomes initiated, it acquires a mutation in a cancer-related gene. Such mutation allows the cell to grow at a higher rate than normal tissue, while keeping a normal phenotype. The still-noninvasive tissue undergoes hyperplasia/dysplasia as the initiated cells proliferate more than nearby normal cells, but still not disrupting the basal membrane.
The tumor becomes malignant when it can break through the basement membrane and invade blood vessels, thus traveling to distant organs and starting new growth. Metastasis refers to established growth in a distant organ. The ability of a tissue to become a malignant tumor depends on several processes: evading apoptosis, growth signal self-sufficiency, insensitivity to anti-growth signals, limitless replicative potential, sustained angiogenesis, and tissue invasion/metastasis.
Cancer is the second leading cause of death in the U.S. Some cancer types are more responsive to therapy than others. In all types of cancer, treatment of metastatic disease is difficult and often unsuccessful.
Classification of Tumor Growths
A neoplasm is a new growth, either benign or malignant. Benign neoplasms are non-invasive, highly differentiated, non-metastatic, have a low number of mitoses and grow slowly. Malignant neoplasms are invasive, poorly differentiated, may be metastatic, have a high number of mitosis and grow rapidly.
Human tumors can be classified as either carcinomas, leukemias/lymphomas or sarcomas. A carcinoma is a malignant neoplasia of epithelial cells. The word "carcinoma" comes from the greek "karkinoma", named by Hippocrates from "karkinos", the crab, because of the invasive nature of malignant cancer. Leukemia is cancer of the blood cells. Lymphoma is cancer of the lymph cells. Sarcoma refers to cancer of non-epithelial tissue, like muscle, bone, blood vessels or cartilage. Most human cancers are carcinomas (85%), followed by leukemias/lymphomas (10%) and sarcomas (5%).
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to "Epithelial Changes" or take
a quiz: [Q1].
Back to Basics: Homeostasis and Tissue Types (Physiology)
Need more practice? Answer the review questions below.
1- What is cancer (short answer)?
2- What is a malignant tumor?
3- Why is cancer fatal?
4- Regarding a tumor, what does the phrase "heritably altered" refers to?
5- Why is a malignant tumor capable of autonomous growth?
6- What does it mean for a tumor to be "invasive"?
7- List 4 requirements for a normal epithelium to be transformed into a malignant epithelium, in order of occurrence.
8- Why is the first requirement (see your answer to #7) for normal epithelium to be transformed important?
9- Briefly describe the initial stages of hyperplasia, before malignancy.
10- When does a tumor becomes malignant?
11- What is metastasis? (short answer)
12- List the 6 characteristics that allow a tumor to become malignant.
13- What is a neoplasm ? (short answer)
14- List 5 characteristics of a benign neoplasm.
14- List 5 characteristics of a malignant neoplasm.
15- List 3 general types of human tumors, in order of the most common to the least common.
16- What is a carcinoma?
17- What is leukemia?
18- What is lymphoma?
19- What is sarcoma
Continue scrolling to answers below.
Hey! DON'T PEEK!!! Finish the questions fist!
1- What is cancer
(short answer)?
Cancer is a disease
of malignant cell growth.
2- What is a malignant
tumor?
A malignant tumor is an inheritably altered, relatively autonomous growth of
tissue which ultimately invades and interferes with the function of normal tissues.
3- Why is cancer
fatal?
Cancer can be fatal because a tumor will interfere with normal function of tissues.
4- Regarding a tumor,
what does the phrase "heritably altered" refers to?
A tumor is heritably altered because the DNA mutations required for
the tumor to develop are passed on to daughter cells.
5- Why is a malignant
tumor capable of autonomous growth?
The autonomous growth of a tumor is due to its insensibility to normal
growth control mechanisms.
6- What does it
mean for a tumor to be "invasive"?
Invasion refers to the tumor's ability to start additional malignant tumors
beyond the boundaries of the original growth.
7- List 4 requirements
for a normal epithelium to be transformed into a malignant epithelium, in order
of occurrence.
initiation
hyperplasia
invasiveness
metastasis.
8- Why is the first
requirement (see your answer to #7) for normal epithelium to be transformed
important?
When a cell becomes initiated, it acquires a mutation in a cancer-related gene.
Such mutation allows the cell to grow at a higher rate than normal tissue, while
keeping a normal phenotype.
9- Briefly describe
the initial stages of hyperplasia, before malignancy.
The still-noninvasive tissue undergoes hyperplasia/dysplasia as the initiated
cells proliferate more than nearby normal cells, but still not disrupting the
basal membrane.
10- When does a
tumor becomes malignant?
The tumor becomes malignant when it can break through the basement membrane
and invade blood vessels, thus traveling to distant organs and starting new
growth.
11- What is metastasis?
(short answer)
Metastasis refers to established growth in a distant organ.
12- List the 6 characteristics
that allow a tumor to become malignant.
evading apoptosis
growth signal self-sufficiency
insensitivity to anti-growth signals
limitless replicative potential
sustained angiogenesis
tissue invasion/metastasis.
13- What is a neoplasm
? (short answer)
A neoplasm is a new growth, either benign or malignant.
14-List 5 characteristics
of a benign neoplasm.
non-invasive
highly differentiated
non-metastatic
have a low number of mitoses
grow slowly
14-List 5 characteristics
of a malignant neoplasm.
invasive
poorly differentiated
may be metastatic
have a high number of mitosis
grow rapidly
15- List 3 general
types of human tumors, in order of the most common to the least common.
carcinomas (85%)
leukemias/lymphomas (10%)
sarcomas (5%)
16- What is a carcinoma?
A carcinoma is a malignant neoplasia of epithelial cells.
17- What is leukemia?
Leukemia is cancer of the blood cells.
18- What is lymphoma?
Lymphoma is cancer of the lymph cells.
19- What is sarcoma
Sarcoma refers to cancer of non-epithelial tissue, like muscle, bone, blood
vessels or cartilage.