Bongs filter between 50 and 90 percent of tar, 70 and 90 percent of carcinogens.
Cancer is caused by abnormal cell division, and that can be caused by 2 things
1: constant irritation
2: high presense of carcingoneic material

Now, smokers (cigarettes) are constantly smoking (irritation) and taking in lotsa carcinogenic material
Weed smokers tak in less smoke, less often, and there is less carcinogenic material.
tobacco companies add chemicals into their product.
weed is all natural. no additives

thus
weed=safer than tobacco

Ergo (X equals set amount)
tobacco = more smoke taken in, more carcinogenic material per X amount taken in.
Weed=Less smoke taken in, less carcinogenic material per X taken

X Weed = less harmful than X tobacco

Normally, X Tobacco is taken 12+ times daily
Normally, X Weed is taken 1-3 per day, depending on frequency of use .

Tobacco is used daily, and is also used very frequently per day.

Weed is used very infrequently per day, and usually not every day.

Tobacco = more frequent, more damage.

Weed is therefore better for you than tobacco

Tobacco takes years of smoking to get cancer (ten +)

you smoke about 1/5th of the amount of weed than most do tobacco

tobacco = 5x weed = X

so, 50 years of weed smoking will get you cancer. maybe.

So, In conclusion, no, weed will prbably not give your cancer