Go through these in order and stop at the first one that applies. If you are reading this for someone else, answer for them.
1
Is any of this happening now?
Call 911
Seek emergency help for:
Severe or rapidly worsening difficulty breathing
Coughing up more than a small amount of blood
New weakness on one side, a seizure, collapse, or severe confusion
Sudden chest pain, especially with breathlessness
Blue or grey lips, extreme drowsiness, or inability to speak normally
These signs can have causes other than cancer, but they require immediate assessment.
And for anyone, someone who:
is struggling to breathe, gasping, choking, or cannot get words out
Other emergency signs, for anyone
Someone who has chest pain, tightness or pressure lasting more than a few minutes
Someone who has sudden weakness or drooping on one side of the face or body, slurred speech, or sudden confusion
Someone who is unconscious, or cannot be woken
Someone who is bleeding heavily and it will not stop with firm pressure
Someone who has had a seizure that will not stop, or does not wake up afterwards
Someone who has lips or skin that look pale, blue, grey or blotchy
Someone who you believe has taken an overdose or swallowed something poisonous
2
Is any of this happening?
Be seen today
Small streaks of blood in mucus also need prompt assessment, even if you otherwise feel well.
If you are receiving cancer treatment, contact your cancer team promptly about a fever, shaking chills, a new rash, diarrhoea that continues, worsening cough, new breathlessness, unusual weakness, or other symptoms they have told you to report.
Follow the team's specific instructions for treatment-related fever.
3
Does any of this apply?
Book an appointment
Arrange a routine medical assessment if you have a persistent cough, a change in a long-standing cough, unexplained weight loss, repeated chest infections, ongoing chest discomfort, or worsening breathlessness.
And for anyone, someone who:
has noticed a lump, a mole that has changed, or unexplained weight loss
Every sign above is quoted from the sofidex article on Non-small cell lung cancer. If you are not sure, err upward — it is always reasonable to be checked.