How is invasion and metastasis in cancer?

Result from interaction between cancer cells, stromal cells, and ECM, start with local invasion to intravasation to blood and lymph, go through blood, extravasation from vessels, formation of micrometastasis, growth into macrometastasis. May be interrupted by host/ tumor factors. Carcinoma breaches basement membrane first, then ECM then circulation, can be resolved by loosening intercellular connections between tumor cells, local degradation of basement membrane, changes in attachment of tumor cells to ECM, locomotion Tumor cells or tumor derived DNA go through blood, mostly as single cells and rare aggregating emboli, in blood they are vulnerable to degradation and don't proliferate. Site of metastasis depends on location and tropism of tumor cells to specific places, frequent liver and lung all cancers, Particular (prostate->bone, broncho->adrenals and brain, neuro->liver and bones