Almost 90% of lung cancer cases are caused by cigarette smoking, making it the leading lung cancer risk factor.

Some symptoms include:

Any thickening or bump on the body Weight increase or loss without apparent cause
a wound that doesn't get better
voice hoarseness or a persistent cough
difficulty swallowing
discomfort following a meal
alterations in bowel or bladder patterns
unexpected bleeding or discharge
being extremely fatigued or feeble.

What Is the Relationship Between Smoking and Cancer?
Tobacco use can cause cancer and then prevent your body from fighting it:

Toxins in cigarette smoke can weaken the immune system, making it more difficult to kill cancer cells. When this occurs, cancer cells continue to grow unabated.
Tobacco smoke contains toxins that can harm or change the DNA of cells. DNA is the cell's "instruction manual," controlling normal cell growth and function. When a cell's DNA is damaged, it can cause it to grow out of control and form a cancer tumour.
For many years, doctors have known that smoking is the leading cause of lung cancer. It is still true today, when smoking cigarettes or being exposed to secondhand smoke causes nearly 9 out of 10 lung cancer deaths.

cigarette smoke:

Smoking cessation reduces the risk of 12 cancers: lung, larynx, oral cavity and pharynx, oesophagus, pancreas, bladder, stomach, colon and rectum, liver, cervix, kidney, and acute myeloid leukaemia (AML).
Your chances of developing cancer of the mouth, throat, or voice box are cut in half within 5-10 years of quitting.
Within 10 years of quitting, your chances of developing bladder, esophageal, or kidney cancer decrease.
Your risk of lung cancer is cut in half within 10-15 years of quitting smoking.
Within 20 years of quitting smoking, your risk of developing cancer of the mouth, throat, voice box, or pancreas drops to that of a nonsmoker.

How Does Cancer Get Treated?
Cancer treatment is determined by the type of cancer and the stage of the disease (how severe the cancer is and whether it has spread). Doctors may also take into account the patient's age and overall health. The goal of treatment is frequently to cure the cancer. In other cases, the goal is to keep the disease under control or to reduce symptoms as long as possible. A person's treatment plan may change over time.

Surgery, radiation therapy, or chemotherapy are common treatment options. Biological therapy is another plan (a treatment that helps your immune system fight cancer).

Some cancers respond best to a single treatment method. Other types of cancer may benefit from a combination of treatments.