Most common cause of brain metastasis is?

Ans. is 'a' i.e., Carcinoma lung * Metastasis to brain are the most common brain tumor. Most common primary malignancy metastatizing to brain is lung carcinoma, followed by (in decreasing order of frequency) breast, skin (melanoma), kidney (genitourinary) and GIT cancers.* Prostate carcinoma, ovarian carcinoma and Hodgkin's disease are very unlikely to metastatize to brain.