An effusion in cancer refers to which phenomenon?

• A. Fluid accumulation in body cavities caused by cancer
• B. Increase in cell number but cell remains normal
• C. Abnormal development or growth of cells (precancerous)
• D. Invasion of tumor cells into bone

Answer: (A)

Fluid build-up in body cavities is what an effusion is. In cancer, effusions arise when tumor involvement or the associated inflammation causes fluid to collect in spaces such as the pleural space around the lungs, the peritoneal cavity in the abdomen, or the pericardial space around the heart. This happens due to tumor irritation, increased vascular permeability, and blockage of lymphatic drainage, leading to fluid accumulation rather than changes in cell number or growth.

So the best description is fluid accumulation in body cavities caused by cancer. The other options describe changes in cells (increase in number with normal cells, precancerous growth) or invasion into bone, which are not what an effusion represents.