hi friend
i am sorry to hear about your father's diagnosis
i must say that yes
cancer does happen with no symptoms at all til the very late stages
having said that
cancer can mimic many other diseases
and therefore difficult to diagnose
that in fact is the reason why most of the cancers
which can be effectively treated are not fully treated
because by the time they are detected they are out of control
and spread beyond a local region
and therefore not fully treatable by
radiation or surgery
in your father's case
i would suggest you meet a cardiothoracic surgeon too
if the dr feels they are up to it
maybe resection of a part of the lung will help
but i have no idea about his scans
so i dont know if he is fit for the option
i am just basing my belief assuming that if he is mobile as you say
he might be fit
of course chronic neck and
shoulder pain can be neuropathy
as i said cancer can be silent and mimic
hope that answers your query
best of luck