Unexpected Causes of Lung Cancer

In just 2014 alone, 155,610 Americans died from lung cancer — more deaths than breast, colon, and prostate cancer combined. According to the CDC, Oklahoma has the fifth-highest rate of lung cancer diagnoses in the nation at 68.7 per 100,000 people. Most lung cancer prevention efforts focus on the avoidance of tobacco, and rightfully so, with smoking and secondhand smoke contributing to 80 to 90 percent of lung cancer cases. But surprisingly, an estimated 10 to 15 percent of lung cancer patients across the U.S. have never smoked a single cigarette.

Lung Cancer in Non-Smokers

For non-smokers diagnosed with lung cancer, the culprit is typically non-small cell lung cancer, which is a broad term for several types of cancer cells that affect the lungs in a similar way. Non-small cell lung cancers include adenocarcinoma, large cell carcinoma and squamous cell carcinoma. Sadly, many of those diagnosed with non-small cell lung cancer are younger -- even in their twenties -- and often by the time they are diagnosed, the cancer is more advanced.

“There are differences that we see in the types of lung cancer that smokers and non-smokers tend to develop. Generally, non-smokers have a much higher proportion of a type of lung cancer called adenocarcinoma. What we look for in these lung adenocarcinomas are specific molecular markers that can highlight either favorable tumors or specific treatment targets. Unfortunately, these markers are present in only a minority of adenocarcinomas, but those cancers that harbor these mutations can sometimes be controlled for quite a length of time,” says Dr. Shripal Bhavsar, a radiation oncologist at INTEGRIS. In just the past decade, researchers have made significant strides in identifying the causes of lung cancer in non-smokers, but compared to other more common types of cancer, much is still unknown. Some researchers suspect a hereditary link, as in certain forms of breast cancer, while others suspect a genetic predisposition to the disease made worse by certain environmental factors.

“We have been finding more cancers in non-smokers and younger patients. Partly this is because we are doing more imaging in health care, and we inadvertently find lung nodules more often than ever before. Also, as more of the population has access to health care, we will find more of these cancers at an earlier point,” Dr. Bhavsar explains.

The following risk factors have been identified as causal factors, but there is still much to be learned. In any case, taking steps to lower your exposure to risk factors, if possible, can’t hurt.

Lung cancer risk factors other than tobacco

Harmful substance exposure

Exposure to radon gas

When uranium in soil, rock and water breaks down, the resulting gas by-product of radon can become part of the air we breathe. Older homes may be susceptible to high levels of radon. Radon testing kits, available for purchase at home improvement stores, can determine whether levels are unsafe.

Gene mutations

“In the absence of significant risk factors, there is a higher chance of finding a genetic driver in the tumor of a younger patient,” Dr. Bhavsar says. Young people and non-smokers diagnosed with lung cancer commonly have mutations in genes known as EGFR, ALK and ROS1. New forms of targeted therapy are being developed and tested to treat lung cancer in patients with these gene mutations.