How does lung cancer affect the respiratory/skeletal system if it spreads there?

Can it affect any other human systems?

The most common secondary site for lung cancer are the bones and the brain. Metasteses in bone increase likelihood of fracture and non-union of fractures, and of course severe bone pain (usually most evident in hips and spine).
Secondary cancer in the brain can cause a range of symptoms, usually affecting balance, paralysis or altered sensation on one side of the body etc.
Lung cancer will affect respiratory function by decreasing the amount of oxygen in the bloodstream which leads to excessive carbon dioxide levels.

my mom has stage 4 lung cancer. about 2 months ago, the tumor in her left lung pressed on her airway, causing her to feel like she was suffocating, and also collapsed her right lung.
she has been having radiation to break up the tumor. she's breathing better, but it could happen again.

as for the skeletal system? yeah, her cancer has been metasticized to her bones since she was diagnosed back in october 2007. she's been in horrible pain for the past 3 weeks, with no end in sight. they're doing radiation for it, but it's a slow, arduous procedure.

my mum has recently been diagnosed with lung cancer and she has four secondary tumours, three in her brain and one on her kidney. Lung cancer is like a tree with roots and it tends to branch out and grow both up and down. It is very common for lung cancer to spread to the brain especially and in most cases at some point it will spread to some other part of the body (unless caught extremely early and successfully treated).

Cancer sorta eats at and caused decay and malfunction in whatever part of the body it attacks. It has a tendacy to spread to other body parts also. It is not contagious to others by touching that person--if this is your second question.