Answer: The spread of cancer cells from the primary tumour to distant organs via blood or lymph, forming secondary tumours; harder to treat because it affects multiple organs and is harder to remove surgically.
- A A type of largely benign tumour that, by definition, rarely spreads beyond its original tissue of origin under any clinical circumstance, no matter how long the tumour is left untreated or how large it eventually grows
- B The spread of cancer cells from the primary tumour to distant organs via blood or lymph, forming secondary tumours; harder to treat because it affects multiple organs and is harder to remove surgically
- C Metastasis is generally understood by oncologists to make a diagnosed cancer considerably easier to largely and successfully treat, since it confines the disease neatly to one single organ that is simple to remove
- D Metastasis is a process that some medical textbooks describe as occurring mainly in cases of primary liver cancer, and is rarely observed to occur in any other organ or cancer type
Correct answer: B. The spread of cancer cells from the primary tumour to distant organs via blood or lymph, forming secondary tumours; harder to treat because it affects multiple organs and is harder to remove surgically
Explanation: Metastasis: cancer cells detach from primary tumour, invade blood/lymph vessels, survive in circulation, arrest at new sites, extravasate, and grow as secondary tumours. Steps (invasion-metastasis cascade): local invasion, intravasation, systemic transport, extravasation, colonization. Secondary tumours are often more lethal. Treatment is complex: surgery, chemo, radio, targeted therapy at multiple sites.
The Plasmodium parasite needs both hosts: the female Anopheles mosquito injects sporozoites while biting (infecting the human liver and RBCs, causing the malaria fever cycle), then picks up gametocytes from an infected person's blood, completing the parasite's sexual stage inside the mosquito.
Concept context
Pathogens, infectious diseases, non-infectious diseases, drugs, cancer, and public health. High NEET importance.