Lung cancer is one of the most common types of cancer diagnosed worldwide. There are two types of lung cancer: small cell lung cancer (SCLC) and non-small cell lung cancer (NSCLC). NSCLC makes up 80 percent to 85 percent of lung cancer diagnoses. The condition has several subtypes, and the subtype of lung cancer affects its treatment and overall prognosis (disease outlook).
The prognosis for a particular condition is sometimes expressed as a five-year survival rate; that is, the average percentage of people who are still living at least five years after their cancer diagnosis. The five-year survival rate of NSCLC is 25 percent, the highest five-year survival rate of any type of lung cancer. Early diagnosis and treatment of NSCLC can help improve the prognosis.
In addition to early detection, other prognostic factors might influence the disease outlook for NSCLC, including the following.
NSCLC is most commonly diagnosed in older people. The average age at which people are diagnosed is 70. People diagnosed with NSCLC at a younger age (under 40) tend to have a poor prognosis, but early intervention can improve the outcomes.
Healthier individuals — those that practice good nutrition, exercise, and have fewer other health conditions — tend to live longer and have an improved chance of achieving remission (the reduction or disappearance of the signs and symptoms of a condition). High levels of inflammation throughout the body can indicate poor health. Researchers have recently determined that cancers can produce inflammation in their proximity that masks them against the immune system’s attack.
One oncology study showed that people who had high levels of inflammation at diagnosis had a worse prognosis than those who had normal levels of inflammation. People with high levels of inflammation often have other complicating conditions, such as malnutrition or chronic diseases that negatively affect prognosis.
Additionally, unintentional or unexplained weight loss can be a poor prognostic factor.
Smoking poses the highest risk factor for developing NSCLC. About 80 percent of deaths caused by lung cancer in men and 90 percent in women are attributed to smoking cigarettes. According to the American Lung Association, men who smoke are 23 times more likely to be diagnosed with lung cancer compared to people who do not smoke. Women who smoke are 13 percent more likely to be diagnosed with lung cancer than nonsmokers. It is recommended that smokers between the ages of 55 and 70 be screened with a low-dose CT scan every year.
Secondhand exposure to smoke also increases the risk of developing and dying from lung cancer. Each year, more than 7,000 Americans who have never smoked die from lung cancer caused by being around secondhand smoke. People who do not smoke have a 20 percent 30 percent higher risk of being diagnosed with lung cancer if they inhale secondhand smoke often, such as at work or at home.
The good news is that some lifestyle changes can improve prognosis even after NSCLC diagnosis. For example, quitting smoking can improve a person’s health and well-being and can help them tolerate chemotherapy better.
The immune system is designed to recognize and fight against cancer. The types and numbers of immune cells that respond to an NSCLC tumor can influence prognosis. For example, lung tumors that have been invaded by T cells (which can kill cancer cells) tend to have a better prognosis.
By changing their cell markers, cancer cells can change the way they appear to hide from the immune system. A tumor that avoids immune-system detection has a worse prognosis than a tumor that is visible to the immune system. In some cases, immune cells can relearn how to identify and kill cancer cells. There are several types of therapy aimed at activating immune cells so that they can see and respond to cancerous cells.
The over- or underexpression of certain genes and proteins has been linked to NSCLC prognosis. These markers of probable disease outcome are known as prognostic biomarkers. In some cases, the expression of certain proteins can predict how well the cancer cells will respond to treatment. These proteins, known as predictive biomarkers, help doctors design the most effective treatment for each individual living with NSCLC.
People with family members who have been diagnosed with lung cancers may be at a higher risk for developing NSCLC. A family history of lung cancer is associated with a decrease in the average age of diagnosis and an increase in the risk of advanced non-small cell lung cancer at diagnosis. This tends to affect females more negatively than males.
Comorbidities are conditions that can occur alongside a primary condition. Having one or more additional health conditions may affect NSCLC prognosis in several ways. First, some conditions associated with lung cancer — such as chronic obstructive pulmonary disease or heart disease — may decrease survival rates independently of NSCLC. Second, comorbidities may also conceal signs and symptoms, leading to delayed diagnosis. Finally, it may be unsafe for a person to undergo certain types of surgery to treat NSCLC if they have certain comorbidities.
Common NSCLC comorbidities include:
For example, about 34 percent of people living with lung cancer also had anemia, one study found. Older people and people who smoke cigarettes are more likely to have additional conditions that complicate treatment or negatively affect prognosis.
Other factors can influence a person’s NSCLC prognosis, including the stage of disease at the time of diagnosis and the NSCLC subtype. The earlier a cancer is detected, the better the prognosis. However, some signs and symptoms of NSCLC tend to develop only after the disease has spread. This means that most instances of NSCLC are diagnosed at a later stage.
Clinical staging is a process during which doctors gather information to estimate where the disease is in its existence before treatment starts. Information from physical exams, CT scans or other imaging tests, blood tests, and biopsies can be used for clinical staging. Clinical staging is often used to estimate an individual’s prognosis.
Overall, tumors that can be surgically removed (also known as surgical resection) are associated with the best prognosis. If surgery is part of treatment, pathological staging may be necessary to get a more accurate picture of the stage and prognosis. Pathological staging of NSCLC is based on the size of the main tumor, whether it has spread to close lymph nodes, and whether it has spread to distant parts of the body. This is called TNM staging, for which the T stands for “tumor,” the N for “nodes,” and the M for “metastases.”
People living with NSCLC that is fully contained in the lungs (localized) have a better prognosis than those with metastatic disease, meaning the cancer has spread beyond the lungs to other parts of the body. For people living with NSCLC that exists only in the lungs, the five-year survival rate is 63 percent. When NSCLC has spread to areas near the lungs (regional), the five-year survival rate is 35 percent. After cancer has metastasized (distant), the 5-year survival rate is 7 percent.
NSCLC is an umbrella term that encompasses several subtypes of lung cancer. The most common subtypes:
These subtypes are caused by different types of lung cells becoming cancerous. The treatment and outlook of these subtypes are typically similar. Subtypes of NSCLC may respond differently to treatment. Advanced medicine allows doctors to find specific cancer cell pathways to target with modern treatment options. This targeted treatment is called personalized medicine and has improved the overall prognosis of NSCLC.
Every year, tens of thousands of people in the United States living with NSCLC achieve complete remission, meaning all signs of their cancer disappear. After treatment ends, most people continue seeing their oncologists for follow-up visits. Tests are performed at these visits — such as physical exams, CT scans, and blood tests — to monitor for signs of cancer relapse. Follow-up visits usually occur every three to six months in the first few years after remission. After two to three cancer-free years, a person’s oncologists may recommend a visit every six months. Prognosis is worse for relapsed disease than at first diagnosis; often, the cancer that has returned is more resistant to treatment.
The best treatment for NSCLC is prevention. People who have never smoked or have quit smoking are at a lower risk of developing lung cancer. Fewer people smoking and advances in diagnosis and treatment of NSCLC have led to improved overall survival over the past 30 years. It's possible for people living with advanced or metastasized lung cancer to enjoy a high quality of life. Newer, targeted therapies are allowing people living with metastatic lung cancer to live longer, healthier lives than was previously possible.
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