<prompt> Most common primary bronchogenic carcinoma isSmall cell carcinomaSquamous cell carcinomaMixed cell carcinomaAdenocarcinoma  <response>: Histological type . Frequency Adenocarcinoma . 32 Squamous cell carcinoma . 29 Small cell carcinoma . 18 Large cell carcinoma. 9 Carcinoid. 1 Ref Harrison 19th edition pg 2584 