Neoplasm/ Tumour – “A mass of tissue formed as a result of abnormal, excessive, uncoordinated, autonomous and purposeless proliferation of cells”

• Oncology – Branch of science dealing with the study of neoplasm

• Transformation from a living normal cell into a living tumor cell

Basic features of change in neoplasia

• Change is irreversible; becomes fixed character of a transformed cell

• Acquired fixed character is heritable; tumor cell divide to give tumor cell

• Change once occurred is self-perpetuating

• Tumor cell has uncontrolled passion for continued proliferation

Classification of tumors

• Based on the nature of tumors, they are classified as

Benign tumor – Harmless and self-limited

Malignant tumor – Harmful and rapidly growing

• Names of every tumor ends with ‘oma’

• Malignant tumor of epithelial tissue – Carcinoma

• Malignant tumor of connective tissue – Sarcoma

Classification of tumor based on tissue of origin

Tissue of origin	Benign	Malignant
Epithelial tumors
1. Squamous epithelium	Squamous cell papilloma	Squamous cell carcinoma
2. Transitional epithelium	Transitional epithelium papilloma	Transitional epithelium carcinoma
3. Glandular epithelium	Adenoma	Adenocarcinoma
4. Hepatocytes	Liver cell adenoma	Hepatocellular carcinoma (Hepatoma)

Tissue of origin (Non epithelial tumors)	Benign	Malignant
Adipose tissue	Lipoma	Liposarcoma
Fibrous tissue	Fibroma	Fibrosarcoma
Cartilage	Chondroma	Chondrosarcoma
Bone	Osteoma	Osteosarcoma
Blood vessels	Haemangioma	Angiosarcoma
Nerve cells	Ganglia Neuroma	Neuroblastoma

Contrasting features of benign and malignant tumor

Features	Benign	Malignant
Macroscopic features
Boundaries	Encapsulated/ well circumscribed	Irregular & poorly circumscribed
2. Surrounding tissues	Often compressed	Usually invaded
Size	Usually small	Often large
4. Secondary changes	Occurs less often	Occurs more often
Microscopic Features
Pattern	Closely resembles the tissue of origin	Poor resemblance to the tissue of origin
2. Basal polarity	Retained	Lost
3. Pleomorphism	Normal	Increased


4. Neuclio- cytoplasmic ratio	Normal	Increased
Hyperchromatism	Absent	Present
Mitosis	Always typical mitosis	Atypical & abnormal mitosis
7. Tumor giant cells	May be present but with atypical nucleus	Always present with atypical nucleus
8. Cytoplasm	With normal constituents	Elements are reduced or lost
9. Functions	Usually well maintained	Retained/ lost/ abnormal
Growth rate	Usually slow	Rapid
Local invasion	Often compresses the surroundings; no invasion/ infiltration	Invade & infiltrate the adjacent tissue
Metastatis (Spreading)	Absent	Present

Structure of tumor

Tumor mass consists of:

Parenchyma
Stroma

Parenchyma

• Formed by proliferating tumor cells

• Parenchyma of benign tumor – organised pattern with resemblance to tissue of origin, differentiation

• Parenchyma of malignant tumor – unorganised, atypical, distorted, relation of tumor cell with basement is lost, anaplasia

Stroma

• Supporting tissue of tumor

• Consists of fibrous tissue carrying blood vessels for nourishing tumor cell

• More malignant the tumor, Cirrhous

• Carcinoma with scanty stroma – celluloid & medullary

• New blood vessels form from pre existing onesless is the fibrous tissue

• Carcinoma with extensive stroma – with the help of a factor, “tumor angiogenesis factor”

Spread of cancer

(Two mechanism for the spread of cancer)

Routes of spread of cancer

1. Infiltration of tissue spaces

• Tissue spaces – preformed passages; paths of least resistance

• Most vulnerable tissues – soft tissues – adipose, muscle,

• Gamete/ compact tissues like capsule of organs, cartilage and bone (not marrow) offer greater resistance

• Tissue subjected to infiltration are destroyed by the proteolytic enzymes & lytic substances elaborated by cancer tissue

• Tissue space invasion brings the tumor cell in direct contact with normal cells, lymphatic and blood vessels

2. Hematogenous spread:

• Carcinoma of lungs, thyroid, kidney and the prostate spread through blood vessels

Tumor cells enter blood stream by 2 ways

Via thorasic duct – either by perforation of vein or by lymphatic drainage
By direct invasion of blood vessels (large veins, venules & capillaries); arteries not involved due to their thick wall

3. Spread via lymphatics: Most common with carcinoma; results in both invasion & metastasis

Spread via lymphatics

Lymphatic spread begins by lodgement of tumour cells in subcapsular sinus via afferent lymphatics entering at the convex surface of the lymph node

Hematogenous spread

4. Spread via serous sacs

• Spread through peritoneal cavity; common in cancer of GIT & ovary

• Trans pleural spread – in carcinoma of lungs and breast

• Trans pericardial spread may also occur

5. Spread along epithelium line surfaces

• Intact epithelium, mucous coat acquires resistance for penetration of tumor

• Implantation tumor – tumor spread along the surface of epithelium

6. Spread via CSF

• Cerebrospinal cavities are affected by the escape of tumor cells from

• the malignant tumor in the brain or meninges

Summary

• A tumour is a mass of tissue formed as a result of abnormal, excessive, uncoordinated, autonomous and purposeless proliferation of cells

• Tumors are classified as benign and malignant

• Benign tumors are harmless and do not spread while malignant tumors are harmful and spread

• Tumor is made up of parenchyma and stroma

• Tumor spread by two mechanism – Haematogenous spread and lymphatic spread

Cancer FAQ

Q1: What is a tumor? A tumor is an abnormal mass of tissue that results from the uncontrolled growth of cells. Tumors can be benign (non-cancerous) or malignant (cancerous).

Q2: What are the main characteristics that distinguish benign and malignant tumors? Benign tumors are typically well-defined, slow-growing, and remain localized. They do not invade nearby tissues or metastasize. Malignant tumors, on the other hand, are fast-growing, invasive, and can spread to other parts of the body, leading to the potential for cancer.

Q3: How are tumors named, and what is the nomenclature used for various types of tumors? Tumors are named based on their tissue of origin and their characteristics. Nomenclature typically includes the type of tissue, cell type, and whether the tumor is benign or malignant. For example, “Adenocarcinoma of the lung” refers to a malignant tumor originating from glandular cells in the lung.

Q4: Can you explain the mechanism of tumor spread or metastasis? Metastasis is the process by which cancer cells spread from the primary tumor to other parts of the body. It involves several steps, including:

Invasion: Cancer cells break through nearby tissues.
Intravasation: Cancer cells enter the bloodstream or lymphatic system.
Circulation: Cancer cells travel to distant sites in the body.
Extravasation: Cancer cells exit the bloodstream or lymphatic system.
Colonization: Cancer cells establish new tumors at distant sites.

Q5: What are some common risk factors for the development of cancer? Common risk factors for cancer include exposure to carcinogens (such as tobacco and asbestos), genetic factors, a weakened immune system, chronic inflammation, radiation exposure, and some viral infections.

Q6: What are the most common types of cancer, and how are they typically diagnosed and treated? Common types of cancer include lung, breast, prostate, and colorectal cancer. Diagnosis often involves imaging tests, biopsies, and blood tests. Treatment options may include surgery, chemotherapy, radiation therapy, immunotherapy, targeted therapy, and palliative care.

Q7: How can cancer be prevented or early detection be promoted? Cancer prevention strategies include a healthy lifestyle (such as avoiding tobacco and limiting alcohol consumption), vaccination against cancer-related viruses (like HPV), and early screening through methods like mammography, colonoscopy, and PAP smears. Early detection is crucial for better treatment outcomes.

Q8: What are the stages of cancer, and how do they affect treatment and prognosis? Cancer staging is a way to describe the extent of cancer’s spread. It helps determine treatment options and prognosis. Stages range from 0 (in situ, localized) to IV (advanced, with distant metastases). The earlier the stage, the better the prognosis and treatment options.

Q9: What role does genetics play in cancer risk, and how can genetic testing be used to assess cancer susceptibility? Genetics can play a significant role in cancer risk. Certain genetic mutations increase susceptibility. Genetic testing can identify these mutations and help assess an individual’s risk, enabling early preventive measures and personalized treatment strategies.

Q10: What are the most promising advancements in cancer research and treatment in recent years? Recent advancements in cancer research include immunotherapy, targeted therapies, and precision medicine. These approaches aim to treat cancer more effectively while minimizing side effects.