Why Lung Cancer is the Deadliest Cancer, and Why it Doesn't Have to Be

Have you ever wondered why, in 2015, lung cancer is still such a deadly disease? If you're like most people, you might not even realize how common or deadly lung cancer is, so let's review the numbers.

In addition to being the most commonly diagnosed cancer worldwide (excluding non-melanoma skin cancer), with 1.8 million cases in 2012, lung cancer is the leading cause of cancer-related death both in the United States and worldwide. The leader by a lot. According to the American Cancer Society, lung cancer kills more Americans (158,000) every year than the next three most common cancers (breast, colon and prostate) combined.

Lung cancer isn't the No. 1 cancer killer simply because it's common; it kills a disproportionately high percentage of the people it affects compared to other cancers. Take breast cancer, for example. It's the most common cancer in women in the U.S., and the second leading cause of cancer deaths, but through a combination of early detection and effective treatment resulting from decades of tremendous investment in research, 89 percent of women diagnosed with breast cancer will survive longer than five years.

The five-year survival rate for all patients with lung cancer is 17 percent -- a statistic that has not changed significantly in decades.

So how is this lack of improvement possible? The number of deaths from breast cancer has fallen consistently since 1989, thanks to a combination of better treatments and early detection through screening mammography. The majority of breast cancers in the U.S. are now detected at a curable stage, and subsequent improvements in adjuvant (post-operative) treatments with chemotherapy and hormonal therapy have led to significant improvements in cure rates.

Lung cancer is inherently more difficult to diagnose because you can neither see nor feel your lungs, so the main way it is diagnosed is when it causes symptoms such as a cough or pain. Unfortunately, symptoms usually only occur when the cancer has become too advanced to cure. However, much like breast, colon or many other common cancers, lung cancers detected as the earliest stage (Stage 1) can be cured with surgery or radiation 80 percent or more of the time.

So how do we advance from 17 percent to 80 percent (or even 100 percent)? A good start is better early detection, which can "stage shift" more patients from late to earlier, more curable, stages. Screening for lung cancer with low-dose lung CT scans has been proven to detect more early-stage cancers and decrease deaths from lung cancer by 20 percent in people ages 55 to 75 who have smoked 30 pack years and have quit for fewer than 15 years. Since 2014, CT screening has been covered by private insurance, thanks to high-level recommendations from the U.S. Preventative Services Task Force, and was approved for coverage by Medicare in 2015 under certain restrictions. Still, it has not yet been widely adopted. Widespread recognition and adoption of CT screening may finally start lung cancer down the path to eradication, following in the footsteps of other cancers with effective screening, such as breast and cervical. We are also working on more effective adjuvant treatments to improve the cure rates for lung cancer patients after surgery, specifically through the National Cancer Institute-sponsored ALCHEMIST trial that targets genetic defects with precision drugs or by harnessing the immune system to eradicate microscopic cancer cells.

Of course, greater public health efforts to prevent tobacco smoking and aid in smoking cessation would have the most dramatic effect on lung cancer death rates. Lung cancer screening will be tightly tied to smoking cessation counseling, which may make both efforts more effective. In the U.S., decreasing smoking rates have led to falling death rates in men since 1991, and in women since 2003. But, while tobacco smoking rates have been falling in the U.S. since the 1970s, the opposite has been true in the developing world. Behavior like this will, unfortunately, keep lung cancer deaths in the top spot, globally, for the foreseeable future -- unless we use our available screening, counseling and treatment tools to stay one step ahead.

Dr. Nathan Pennell is a board-certified medical oncologist who joined the staff of the Taussig Cancer Center in 2008. He specializes in the treatment of thoracic malignancies with a focus on lung cancer, and was appointed director of the TCI lung cancer medical oncology program in 2010. Dr. Pennell's research interests include clinical trials using novel therapies, with a goal of facilitating the movement of new treatments from the laboratory to the clinic. He received his Ph.D. in neuroscience in 1998 and his M.D. in 2002 from the University of Florida College of Medicine in Gainesville, FL. Dr. Pennell completed his internal medicine residency in 2005 at Brigham and Women's Hospital in Boston. His medical oncology fellowship training was completed in 2007 at the Dana Farber Cancer Institute.