About 19 to 24 out of every 100 people diagnosed with stage 3 of lung cancer will live for at least 5 years after diagnosis and treatment.
Combination therapy, involving the use of both chemotherapy and RT, appears to work better than either radiation therapy or chemotherapy alone for people with unresected stage III non-small cell lung cancer.
Adding chemotherapy to radiation therapy doubled the number of lung cancer patients alive after 5 years, and doubled that number again if chemotherapy and radiation therapy were given at the same time rather than sequentially.
Chemotherapy provides only modest survival benefits when given separately (1 to 2 months) in disseminated non-small cell lung cancer.
According to clinical statistics, people with lung cancer stage 3 will have life expectancy of 15 months.

So even though my friend had radical radiotherapy, and they are just offering now, chemo injection, would the life expectancy be slightly longer?