Possible, but doubt
Lung cancer can occur in 27 yrs old who smokes, but chance is very low.
Even if it is cancer, not likely from smoking at this point. If having lung cancer is causing severe back pain, you likely have other symptoms as well..Wt loss, fatigue/malaise, coughing, night sweat etc...So, your symptom of pain likely musculoskeletal strain/sprain. Please see doc for eval..U should stop smoking! good luck.
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with 13 years in practice: