Hi Tina

I know a bit about genetic cancers, my wife had the BRCA1 gene and died last year of peritoneal cancer (related to Ovarian) aged 52. Her mother died of the same thing almost exactly 30 years earlier and she lost a brother to cancer 2 months earlier and 4 cousins.

BRCA is one of the better known gene defects that cause cancer normally ovarian and breast but there can be bowel cases and it now seems that in combination with another gene pancreatic too. We are finding new genetic vulnerabilities all the time - her brother died of bladder cancer he was in his mid 50s and while there's not a known link I think this is suspicious.

There are a number of other genetic disorders that can contribute to other cancers - normally the give away is that people are diagnosed at young age. Since non-genetic cancers are more prevalent as people get older.

One of the things that we never seem to ask of people on this forum with regards to lung cancer is whether people were smokers - I guess it seems too much like "victim shaming" but it's a really really strong link with cancer. If your relatives that had lung cancer were smokers I think you can likely rule them out of a genetic cause. Even if they weren't smokers general air quality or shear bad luck are major causes. 

Your grandmother died of pancreatic cancer and there are some genetic issues that can cause that but it doesn't sound as if she was unusually young and unless there are other pancreatic cancers, breast, ovarian cancers or skin cancers in the familly that sounds unlikely to be a genetic cancer (There are links with some of these and pancreatic cancer).

That leaves us with your uncle's testicular cancer whilst men who have a relative with testicular cancer are up to 8 times more likely to get it themselves I'm not aware of any link to other cancers.

Whilst you have a lot of people in your familly who have had cancer the fact is that 50% of people will be diagnosed with some form of cancer in their life time

www.cancerresearchuk.org/.../lifetime-risk

So while I'm not a specialist I would say that there doesn't seem to be a particular pattern here that suggests a genetic cancer risk to me

I hope you find that somewhat reassuring 

Incidently regarding the disapointingly short time that your relatives had after lung cancer diagnosis that is sadly quite common and we do see quite a few people who come on here to tell us that they have a familly member who has been diagnosed with stage 4 lung cancer only to succumb to it weeks later.

Small cell lung cancer is the more aggressive form, it grows faster and spreads quicker. Fewer than 1 in 3 people diagnosed with stage 4 small cell lung cancer make a year so the way things worked out is much as you'd expect I'm afraid