Cancer: Characteristics and History

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Questions and Answers

Which scientist proposed that all cells, including cancer cells, are derived from other cells?

Johannes Muller

Sigmund Freud

Rudolph Virchow (correct)

Karl Thiersch

What theory did Rudolph Virchow propose regarding cancer?

Genetic mutation theory

Chronic irritation theory (correct)

Liquid metastasis theory

Budding element theory

Which type of cancer originates in the tissues responsible for producing new blood cells?

Carcinoma

Lymphoma

Sarcoma

Leukaemia (correct)

Which of the following is NOT one of the six essential alterations in cell physiology for malignant growth?

Increased nutrient absorption Signup and view all the answers

Which type of cancer is primarily epithelial in origin?

Carcinoma Signup and view all the answers

What mechanism did Karl Thiersch demonstrate regarding the spread of cancer?

Through malignant cells Signup and view all the answers

What was a common belief about the cause of cancer until the 1920s?

Trauma Signup and view all the answers

What type of cancer is mesothelioma derived from?

Mesothelium Signup and view all the answers

What is the normal counterpart of an oncogene called?

Proto-oncogene Signup and view all the answers

What happens to tumor cells that avoids apoptosis?

Tumor cells can lead to tumor formation Signup and view all the answers

Which of the following best describes the role of autophagy in cancer cells?

It has opposing roles depending on the context Signup and view all the answers

What characterizes malignant cells in terms of tissue interaction?

They invade surrounding normal tissue Signup and view all the answers

What is the primary function of the autophagic pathway?

To deliver cellular materials for degradation Signup and view all the answers

What happens to the apoptotic rate as tumor mass increases?

Apoptotic rate decreases Signup and view all the answers

Which designation indicates a viral origin of an oncogene?

v- Signup and view all the answers

What percentage of cancer cases are directly caused by hereditary genetic defects?

Less than 10% Signup and view all the answers

In cancer treatment, interventions to modify autophagy are proposed for which purpose?

To stimulate and inhibit autophagy as needed Signup and view all the answers

Which hormones are mentioned as playing a role in cancer development?

Insulin-like growth factors Signup and view all the answers

What is the primary method of cancer treatment that involves the removal of tumors?

Surgery Signup and view all the answers

What is the primary effect of radiation therapy in cancer treatment?

Killing cancer cells Signup and view all the answers

Which type of cancer is NOT influenced by hormones according to the content provided?

Skin cancer Signup and view all the answers

Which of the following statements about chemotherapeutic treatment is correct?

It uses drugs to kill cancer cells. Signup and view all the answers

What is the estimated percentage of the population that carries a genetic mutation significantly affecting cancer risk?

About 0.3% Signup and view all the answers

Which type of cancer is mentioned as being influenced by hormones?

Thyroid cancer Signup and view all the answers

What is a characteristic behavior of cancer cells compared to healthy cells?

Cancer cells can spread to other body parts. Signup and view all the answers

How did Hippocrates conceptualize the cause of cancer?

Through the imbalance of the body's humors. Signup and view all the answers

What was Galen's stance on the treatment of breast cancer?

Advised purgatives instead of surgical methods. Signup and view all the answers

What did the historical document, the Edwin Smith Papyrus, refer to?

The first written account of breast cancer. Signup and view all the answers

The term 'cancer' is derived from which language and what does it refer to?

Greek; meaning crab. Signup and view all the answers

What theory followed the humoral theory in the historical understanding of cancer?

The lymph theory. Signup and view all the answers

Which historical figure believed that cancer could be contagious?

Zacutus Lusitani. Signup and view all the answers

What process allows cancer cells to spread from one part of the body to another?

Metastasis. Signup and view all the answers

What distinguishes in situ cancer from invasive cancer?

In situ cancer has malignant cells above the basement membrane. Signup and view all the answers

Which process is essential for both primary tumor growth and metastasis?

Angiogenesis Signup and view all the answers

What is the first step in the metastatic process?

Accessing the circulation from the primary site Signup and view all the answers

What role do oncogenes and tumor-suppressor genes play in tumors?

They induce angiogenesis responses. Signup and view all the answers

What must happen after cancer cells are shed into circulation during metastasis?

They must lodge in a new organ and extravasate. Signup and view all the answers

What changes occur during the invasion process of cancer?

Destruction of the extracellular matrix Signup and view all the answers

Which statement best describes the role of hypoxia in tumors?

It creates local selection pressures for angiogenesis. Signup and view all the answers

What is a characteristic feature of metastatic single cells?

They may remain dormant for years as micrometastases. Signup and view all the answers

Study Notes

Cancer: A Relentless Division

Cancer cells are characterized by their uncontrolled division, forming tumors or flooding blood with abnormal cells.
Normal cells divide for growth and repair, stopping when no longer needed.
Cancer cells, however, continue dividing indefinitely.
They also possess the ability to spread to other parts of the body, a process known as metastasis.

A Glimpse into Cancer History

The earliest known mention of cancer dates back to 1600 BC in the Edwin Smith Papyrus, describing breast cancer.
Hippocrates described various cancers, using the Greek word "karkinos" (crab) to refer to their appearance.
Galen, disagreeing with surgery, suggested purgatives for treatment. This approach persisted for a millennium.

Humoral and Lymph Theories

Hippocrates proposed the humoral theory, suggesting an imbalance of bodily fluids, particularly black bile, could cause cancer.
The lymph theory followed, attributing cancer to fermenting and degenerating lymph with varying density and acidity/alkalinity.
John Hunter, a Scottish surgeon, believed tumors grow from lymph constantly released from blood.

The Cellular Nature of Cancer

Johannes Muller, in 1838, demonstrated cancer's cellular composition, rejecting the lymph theory.
He suggested cancer cells originated from elements between normal tissues, termed "blastema."
Rudolph Virchow proposed that all cells, including cancer cells, stem from other cells, suggesting a chronic irritation theory where cancer spreads like a liquid.
Karl Thiersch, in the 1860s, proved cancer metastasizes by spreading cells, not through a liquid.

Cancer Cell Types

Cancer cells are categorized based on their origin.
Carcinoma is the most common, originating in epithelial tissues lining body surfaces.
Leukemia originates in blood-forming tissues, typically in bone marrow.
Lymphoma and myeloma are derived from immune system cells.
Sarcoma arises from connective tissues, including fat, muscle and bone.
Central nervous system cancers originate in brain and spinal cord cells.
Mesothelioma originates in the mesothelium, the lining of body cavities.

Six Hallmarks of Malignant Growth

Self-sufficiency of growth signals: Cancer cells can stimulate their own growth without external signals.
Insensitivity to growth-inhibitory signals: Cancer cells ignore normal stop signals, continuing to divide.
Evasion of apoptosis: They can circumvent programmed cell death, preventing their elimination.
Potential for limitless replication: Cancer cells have the capacity for indefinite division, unlike normal cells.
Angiogenesis: They induce the formation of new blood vessels to support tumor growth.
Invasion and metastasis: Cancer cells can invade surrounding tissues and spread to distant sites.

Oncogenes and Proto-oncogenes

Normal cellular genes that contribute to cancer when altered are called oncogenes.
Their normal counterparts are referred to as proto-oncogenes.
Oncogenes are designated by three-letter abbreviations (e.g., myc or ras).
They are further categorized as "v-" for virus or "c-" for cell, indicating their origin.
Over 100 oncogenes have been identified.

Apoptosis in Cancer

Apoptosis is a programmed cell death mechanism.
Cancer cells evade apoptosis to enable tumor formation.
Tumor growth depends both on increased proliferation and reduced apoptosis.

Autophagy in Cancer Cells

Autophagy is a cellular pathway for breaking down proteins and organelles.
This process delivers cellular materials to lysosomes for degradation.
It helps maintain a balance between anabolism and catabolism for normal cell growth.
Autophagy can either eliminate cancer cells or promote tumor development, depending on the context.
Both stimulating and inhibiting autophagy are considered potential anticancer treatments.

Cancer Invasion: Breaking Through Barriers

Cancer cells' ability to invade surrounding normal tissues is a key characteristic.
"In situ cancer" refers to tumors confined to the basement membrane, while "invasive cancer" indicates cells breaching the membrane and penetrating surrounding tissue.
Invasion involves changes in cell adhesion, motility, and degradation of the extracellular matrix.

Angiogenesis: Building a Blood Supply

Angiogenesis is the formation of new blood vessels from existing ones.
This neovascularization is crucial for tumor growth and metastasis.
Tumors develop an angiogenic phenotype through accumulated genetic alterations and response to local pressures, like hypoxia.
Many oncogenes and tumor suppressor genes influence angiogenesis.

Metastasis: Spreading the Disease

Metastasis involves the spread of cancer cells from the primary site to distant sites.
The process involves several steps:
- Accessing the circulatory system (blood or lymph).
- Surviving in the circulation.
- Lodging in a new organ.
- Extravasation (exiting the blood vessels).
- Initiating growth in the new tissue.
- Establishing vascularization for the new tumor.

Hereditary Cancer

Hereditary cancers are primarily caused by inherited genetic defects.
Less than 0.3% of the population carries genetic mutations with a significant impact on cancer risk.
These mutations cause less than 3-10% of cancers.

Hormones and Cancer

Some hormones contribute to cancer development by promoting cell proliferation.
Insulin-like growth factors and their binding proteins play a role in cancer cell growth, differentiation, and apoptosis.
Hormones are crucial in sex-related cancers (e.g., breast, prostate, ovary), as well as thyroid and bone cancers.

Management of Cancer: Treatment Options

Surgery: Removal of cancerous tissue from the body.
Radiation therapy: Using high doses of radiation to kill cancer cells and shrink tumors.
Chemotherapy: Using drugs to destroy cancer cells.

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Description

Explore the relentless division of cancer cells and their unique characteristics, including their ability to metastasize. Delve into the historical perspectives on cancer, dating back to ancient civilizations and the evolution of treatment theories from Hippocrates to Galen.