If weed has tar, which i know it does, than why cant you get lung cancer from smoking weed?

I know for a fact that weed has more tar than cigarettes. I also know that tar is a major reason for lung cancer... so why is it that no one has ever gotten lung cancer from smoking weed....and please dont say that weed can cause lung cancer because it isnt an opinion or what you think....it is a proven statistic that there has never been a case of cancer stemming from weed.....so what ever lies schools are feeding you are false.....there has never been a link from weed and cancer.....so basically i just wanna know does tar really cause lung cancer? and if it does why dont you get it from smoking weed?