Non-small-cell lung cancer (NSCLC) is one of the two main types of lung cancer, accounting for about 85% of cases. NSCLC is a heterogeneous group of cancers that includes adenocarcinoma, squamous cell (epidermoid) carcinoma, and large cell (undifferentiated) carcinoma. Small cell lung cancers (SCLC), which represent the rest, have only two main subtypes – small cell carcinoma and combined small cell carcinoma.
Computed tomography (CT) scans, which provide three-dimensional images, can detect non-small-cell lung cancers at earlier stages than other scanning methods, allowing it to be treated with surgery. Radiation therapy improvements over the past two decades have made it a viable treatment alternative as well.
Unfortunately, the majority of those with lung cancer continue to be undiagnosed until the cancer is at an advanced stage. The American Cancer Society reports that only 16% of lung cancers are diagnosed at a localized stage – that is, while the tumor is still confined to the lung2.
Prevention of smoking and cessation of smoking offer the most important route to decreasing morbidity and mortality, as approximately 90% of cases are due to smoking. With the introduction of molecular tumor testing (or biomarker testing), which looks at tumor DNA mutations and levels of specific proteins, it is now possible to individualize systemic treatment for NSCLC. Expanded drug therapies (including targeted agents) and immunotherapy advances means that systemic treatment can now be optimized for each individual. As a result, life expectancies as well as quality of life have been improving for lung cancer patients: survival rates, according to the National Cancer Institute’s SEER database, are 18.1% for patients treated between 2007 and 2013 versus 15.7% between 1995 and 2000.
Screening for Lung Cancer
Although screenings have been proven effective in detecting earlier stage lung cancers, adoption is not yet worldwide. Screening has long been well-accepted in the U.S.: The National Lung Screening Trial3, conducted in the U.S. from 2002 to 2009, demonstrated that annual low-dose single CT (LDCT) scans reduce lung cancer mortality in high-risk individuals based on age and smoking history. Compared with chest x-rays – an older, traditional mode of screening – the relative reduction in deaths was 20% and the absolute reduction 62 per 100,000 person-years. The trial also found that the number of individuals that needed to be screened in order to prevent one lung cancer death was 320.
In the U.S., lung cancer screening was expanded in February 2015 by Medicare, which covers people age 65 and older. Smokers of at least 30 pack-years, or who are between the ages of 55 and 74 and quit less than 15 years ago, are considered good screening candidates under American Cancer Society guidelines for annual CT scans.
A key question: are lung cancer screenings cost-effective? At this point, that’s not an easy question to answer. LDCT, in both trials and practice, has been found to be associated with a false positive rate of greater than 90%. The need for repeat scans and invasive procedures for these individuals could cause physical and psychological harm.
A recent study of Veterans Health Administration4 (U.S.) efforts to set up a comprehensive lung cancer screening service highlighted both the logistical difficulties in performing screenings and the immense resources required to do so effectively.
In contrast to the National Lung Screening trial, the veterans population not only had significant comorbidity, but also incidental findings such as emphysema, other pulmonary abnormalities, and coronary artery calcification in 40.7% of the patients screened. This can complicate or confound lung cancer screening results.
Screening trials are also currently underway in Europe, but in Asia, which has 51% of lung cancer deaths worldwide, only Japan and Korea have well-established lung cancer screening programs. Other countries – most notably China – are investigating emplacing screening programs.
In Japan, where lung cancer is a leading cause of mortality for both men and women, nationwide screening started in 1987. The screens consisted of chest x-rays and sputum cytology (another way of testing who might be at risk for developing lung cancer), and annual LDCT screening was added in 1993. In Hitachi City Prefecture, where low-dose CT screening among employees and communities began in 2001, lung cancer mortality among employees and in the community of those aged 50-69, in the period from 2005 to 2009, fell by 24% compared with national statistics5.
NSCLC Diagnosis and Staging
The most common signs of lung cancer are cough, hemoptysis (blood in sputum) and dyspnea (difficulty breathing). These symptoms often represent advanced-stage lung cancer. In cases where distant metastases have occurred, common sites are liver, adrenal glands, bones, and brain.
Read More +