<prompt> Which of the following carcinoma most frequently metastasizes to brain -Small cell carcinoma lungProstate cancerRectal carcinomaEndometrial cancer  <response>: Ans. is a i.e., Small cell carcinoma of lung Frequency of Nervous system metastasis by common primary tumour. Site of primary tumourBrain MetastasesLeptomeningeal MetastasisSpinal cord CompressionLung402418Breast194124Melanoma10124Gastrointestinal tract7136Genitourinary tract7-18Others171030 