Final answer:
Carcinomas, which make up at least 80% of cancers, develop from epithelial cells and require a biopsy for diagnosis. They are further categorized based on cell size and shape, with types including those affecting breast, prostate, lung, and colon.
Step-by-step explanation:
Carcinomas develop from the epithelial cells of organs and compose at least 80% of cancers. These are classified by the type of cell that resembles the tumor, with the tissue presumed to be the site of origin. For example, common types include breast, prostate, lung, and colon cancers. Epithelial cells derive from all three major embryonic layers: ectoderm, endoderm, and mesoderm (which gives rise to endothelium). A definitive diagnosis of cancer, including carcinomas, requires a biopsy where a tissue sample is examined microscopically. Cancers are further classified by the scale, such as in lung cancer, where there is a distinction between small-cell and non-small-cell carcinomas, which have different prognoses and treatments.