Modes of Spread of Tumor
• Blood vessels
• Through serous cavity
• Through natural passages
• By inoculation
• Trans-epithelial spread
Spread by Infiltration
Spread of cancer through tissue spaces is one of the chief characteristic of malignant tumor. Cancer cell develop direct extension from the origin to adjoining tissue and organ.
This is the common mode of spread, the tumor cells can easily invade lymphatic channel from the tissue spaces. They may extend along these channels by permeation or they may be carried both to the regional and distant lymph nodes by lymphatic embolism
Spread by Blood Vessels
Cancer cells may reach the blood either by direct invasion of the blood vessels or through the thoracic duct. Veins are invaded easily but the arteries are invaded rarely.
Spread through Serous Cavity/ Transcolomic spread
In which there is frequent transfer of tumor cells from one serous cavity to the other e.g. from the stomach to the ovary.
Spread through Natural Passages Tumor cells may be carried along such passages brochi, bowel and ureter.
Spread by Inoculation
The tumor cells may be inoculated into the surrounding tissue, during the operation by surgeon’s knife and glove.
This spread is observed in Paget’s Disease. Paget’s cells are considered as cancer cells spreading from underline duct carcinoma of breast.
Aetiology of Tumor
Most cancers in adult arise spontaneously in response to unknown stimulus. There are two factors consider being responsible for the causation of tumor:
• Initiating Agent
• Promoting Agent
Initiating agent starts the process whereas the promoting agent carries it to the maturity.
Factors which are considered to be responsible for the causation human neoplasia:
• Chemical Carcinogen
• Physical Carcinogen
• Hormonal Imbalance
• Heredity predisposition
• Cancer following Chronic Disease
• Carcinoma of lung is caused by
o Tobacco smoke and asbestos
• Carcinoma of bladder occurs in
o Aniline dye worker
o Rubber manufacturer
• Carcinoma of Nasal Sinuses
o Wood worker
• Local Acting Chemical Carcinogenic
o Polycyclic aromatic hydrocarbon such as
• Remotely Acting Chemical Carcinogen
o N-methyl-4-aminnobenzene produces liver tumor after oral administration
Physical Carcinogenic Agent
• Solar Radiation (Squamous carcinoma of skin)
• X-Ray (Skin cancer, leukemia)
• Radioactive substance (lung cancer due to Radon, Osteogenic Sarcoma due to ingestion of
Radium and Strontium)
• Heat (Changri Cancer of Abdominal Wall)
Few human neoplasm have associated with viruses
• Warts (Squamous Papillomota)
Cause of Papova virus
• Burkitt’s Lymphoma
As some relationship with the herpes type, Epstein Barr Virus
Hormones can greatly modify the production and growth of tumors. They act as promoter of malignant changes already initiated by some other factors such as viruses and chemical
For example, Estrogen promotes the development of memory cancer which has been initiated by Bittner Virus
Cancer of the breast is somewhat common in the relatives of effective woman. There is well documented cancer family in which there is repeated occurrence of certain tumor, usually carcinoma of breast, ovary or large intestine.
Cancer following Chronic Disease
Formerly it was believed as cancer was the result of prolong stimulation of the tissues through chronic irritation. Physical irritation cannot along produce cancer; it may certainly promote a tumor in a filed already initiated by carcinogenic agent.
It is a type of Chronic Inflammation which means a tumor like mass of granulation tissue. IN granuloma there is aggregation of epitheloid cells surrounded by a core of mono-nuclear leukocytes (lymphocytes and plasma cells)
It is classified into 4 types
Caused by living agent e.g. in case of TB, Syphilis, Lepers, Brucellosis, Sarcoidosis, Actinomycosis, Lymphogranuloma venerum (viral)
Foreign Body Granuloma
Some material which is foreign to the body e.g. dusting powder, cotton wool, cholesterol, suturing material and insect venom
Results by T-Cells mediated immunity to a foreign body with production of Gamma-Interferon e.g. Hematoids arthritis, Giant Cell arteritis
Granuloma of Unknown Etiology
Seen in regional illumitis histocytosis.