Lecture 12 Smoking and cancer Types of lung cancer Non small cell carcinoma 85 includes squamous adenocarcinoma and large cell carcinoma if detected early these may be treated surgically Small cell carcinoma 15 characterized by rapid growth and dissemination treated with chemotherapy and radiation therapy Lung carcinoid tumor 5 grow very slowly and rarely spread Non small cell lung cancer NSCLC Adenocarcinoma usually develops on the outer boundaries of the lungs and is more commonly found in women than in men Cause 40 of lung cancers in US Squamous cell carcinoma commonly starts in the bronchi and may not spread as rapidly as other lung cancers 30 Large cell carcinoma is any lung tumor that cannot be classified Cause of 15 of all lung cancer in US Small cell carcinoma Smoking tobacco major risk Also called oat cell carcinoma can create its own hormones which alter body chemistry Without treatment small cell carcinoma has most aggressive clinical course with median survival of diagnosis of only 2 4 months Greater tendency to be widely disseminated by the time of diagnosis but is much more responsive to chemotherapy and irradiation How does tobacco smoke cause cancer Tobacco smoke is made up of more than 7000 chemicals including 70 known to cause cancer carcinogens Epigenetics methylations turns off genes acting together in some way Carcinogen binds directly to DNA called DNA adducts Chromosomal instability lose arm in chromosome during replication doesn t divide properly RB gene associated with different cancers and mutations in RB genes The smoking gun linking cigarettes to cancer Burning tars in cigarettes create the chemical benzopyrene which is absorbed by lung tissue BP is modified to BPDE and binds to the tumor ruppressing gene p53 BPDE causes mutations at 3 specific hotspots on the p53 gene resulting in unrestricted cell division Facts about addiction to nicotine Nicotine is the tobacco plant s natural protection from being eaten by insects Within 8 secs of first ever puff nicotine arrives at brain s reward pathways Once inside the brain nicotine gains direct and indirect control over the flow of more Men who don t quit smoking lose an average of 13 2 years of life women lose and than 200 neurochemicals average of 14 5 yrs
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