Yeh sorry to hear that B_P ... hope it all goes well for him.
To me it's the ciggies that are doing the real damage , I can really notice it these days I reckion my lung capacity is a 10th of what it used to be.

I'm similar age to your mate and been smoking bongs daily for over 15 years also , I don't smoke as many bongs as I used to but I'm damn sure to make sure nothing Clogs up and well gone are the days of smoking massive tightly packed romper cones (for me). I always just thought it logic that pressuring your lungs like that tryin to suck thru a stomper , with tiny conepeice hole , and so much smoke in one breath was going to be detrimental , I still know 50 years olds who smoke like that tho lol. I found a bit of moderation was the key to truly enjoying these things.
Always has been a massive bong smoking culture In Oz in my experience and especially around the place I grew up ... I have known 3 young mates who wrecked their lungs at young ages , ciggies yes , but supposedly from pulling fat cones for these 3 (1 wasn't a bacco smoker actually , good mate of mine) ...
Anyhoo ... ages were 15 (same ages as me at the time , he suffered collapsed lung and had tubes for months etc)
13 (he'd been choofing since about 10 ... collapsed lung , long hospital stay and hadto stop bongs for many years)
and 17 (didn't smoke cigs , he also had a ruptured lung right after pulling a billy , he's ok now and still smokes bongs as with the other 2 , smaller cones.)
So yeh , very young ages , and attributed to bongs yes ... but ludicrously oversized amounts and 50 cones a day type mentality

some won't be as lucky as others I suppose ... yet there are 1000's more who do the same and never suffer a problem even into later life.
On the other side of the spectrum ... I have two good old mates in their early sixties who smoke bongs every day for decades and although one suffers from a broken back and re-occuring cancer , he's pretty good 8) the other seems in very good health (both smoke ciggies but not many if there is pot).
And I know personally countless others in their 50's and 40's who smoke bongs every day and sometimes all day ... most of which seem healthier than me at my age. So although it's certainly something to pay attention too ... I think It's a relatively rare occurence ... and I bet noone really expects it will happen to them until it does.
I think Bongs are an excellent method for smoking Cannabis ... but safe practises like clean water , using glass not "Orchy" or choco milk bottles heheh , packing the cones lightly and slightly smaller and making sure the conepeice is always well unclogged are the basics I reckon. A small bit of maintanence can go a long way to provide better , cleaner and more efficient highs ... along with preserving the precious lungs in order to smoke the Good herb for many years to come.

... and on that note ...
Cheers.