Health Leader, Lung Cancer 101

STORY BY

Anissa Anderson Orr

Television news lost an icon when Peter Jennings died of lung cancer in August. Now Dana Reeve, who lost her husband Christopher Reeve earlier this year, is fighting the disease.

Their personal, and very public, tragedies are drawing new attention to lung cancer—the leading cancer killer in both men and women. Americans were shocked by how quickly it killed Jennings, who had quit smoking 20 years earlier. Perhaps even more shocking was the fact that Reeve has never smoked.

Regardless of its connection to smoking, lung cancer deserves attention, say doctors. An estimated 172,570 people will be diagnosed with lung cancer and 163,510 people will die from lung cancer in 2005, according to the American Lung Association. The disease kills more than breast cancer, colon cancer and prostate cancer combined. And because it is such a difficult disease to treat, the expected five-year survival rate for lung cancer patients is only 15 percent.

Sneaky disease

Lung cancer survival rates are so low because patients rarely have symptoms until their cancer is widespread. Some types of lung cancer can develop rapidly while other types of lung cancer may take years to develop.

“Lung cancer, unlike other cancers, is a slow, sneaky process,” says Dr. Richard Castriotta, professor of medicine and division director for pulmonary, critical care and sleep medicine at The University of Texas Medical School at Houston. “Most of the lung does not have contact nerve endings or pain fibers, so you don’t feel anything. A tumor can grow in the lung for a long time and spread to other areas without you actually feeling anything. When you have chest pain from the tumor, it is almost always too late.”

Two major types

There are two major types of primary lung cancer: non-small cell and small cell. Each originates in different types of cells in the lungs and grows and spreads in different ways. Non-small cell lung cancer is the most common type, accounting for almost 80 percent of all cases. Squamous cell carcinoma, adenocarcinoma, and large cell carcinoma are three types of non-small cell lung cancer. Smoking causes most cases of squamous cell carcinoma, so doctors treat them differently. A diagnosis will include not only the type of lung cancer but also the stage, which describes the extent and spread of the disease at diagnosis.

Small cell lung cancer, or oat cell lung cancer, is the mostly rapidly growing type of lung cancer and kills the fastest. Smoking almost always causes it.

Lung cancer’s smoking gun

Smoking causes an estimated 87 percent of lung cancer cases. Smoking cigars or pipes also increases the risk of lung cancer. Most cases of lung cancer could be prevented by simply not smoking.

“To put things into perspective, before the advent of mass-produced cigarettes, lung cancer was a rare condition,” Castriotta says. “If a pathologist found a case of lung cancer in autopsy, he would call all the medical students in to look at it.”

The longer you smoke, and the more cigarettes you smoke, the higher your risk is for developing lung cancer. The most damage to the lungs occurs when people start smoking early, in their teens and early 20s. Most lung cancer patients are in their 50s and 60s who have smoked for many years. But no matter how long you have smoked, quitting still can reduce your risk. After you quit smoking, your risk decreases each year as normal cells replace abnormal cells. After ten years, the risk drops to a level that is one-third to one-half of the risk for people who continue to smoke.

Can you get lung cancer even if you don’t smoke? Yes, says Dr. Joan Bull, a professor and director of the Division of Oncology at UT Medical School.

Exposure from “secondary smoke” from a spouse, significant other, or parent who smoked can cause lung cancer in people who never smoked themselves. Some studies show an increased risk of lung cancer in people who were exposed to second hand smoke as children.

“There are genetic risks as well,” Bull says. “Some people probably lack the genes to quickly repair their DNA in their lungs as well and so they develop lung cancer more easily.”

For this reason, women and African-Americans are more at risk for lung cancer.

“They have a much lower pack-year exposure to get lung cancer and they go downhill more rapidly.”

Exposure to radon, usually found in regions where houses have basements, and exposure to radioactive substances can also increase risk for lung cancer. Exposure to chemicals or particles in the air over long periods of time can cause lung cancer. Also, certain types of cancer may start in other areas of the body and spread, or metastasize to the lung.... before the advent of
mass-produced cigarettes, lung cancer was a rare condition. If a pathologist found a case of lung cancer in autopsy, he would call all the medical students in to look at it.”

Finding lung cancer

Many lung cancer patients owe their survival to serendipity – when their cancer is accidentally discovered through x-ray ordered for some other health reason. How often high-risk patients should be screened and what screening tool should be used is controversial. Studies show that routine screening tests detect cancer earlier than they would be found without screening. But there is little evidence that shows screening tests prevent people from dying with lung cancer.

Some in the medical community advocate routine chest x-rays for people at high risk for developing lung cancer. Computerized tomography (CT) scans and positron emission tomography (PET) scans detect lung cancer more accurately. A type of CT scan, called low-dose helical CT scan, can pick up small lesions a couple of millimeters in size.

“Cure rates are almost 70 percent for solitary, asymptomatic tumors less than 1.5 centimeters without obvious spread,” Castriotta says.

PET scans help doctors determine which tumors are malignant because malignant tumors “light up.” Both CT and PET scans have drawbacks, however. CT scans also detect lesions that are not cancerous. And not all types of cancerous tumors light up on a PET scan.

Castriotta says laser-induced fluorescence bronchoscopy (LIFE) shows great promise as a tool for detecting lung cancer. LIFE more accurately detects early cancerous lesions than conventional fiberoptic bronchoscopy using white light— even lesions too small to be seen on CT scans. As a plus, bronchoscopy doesn’t use radiation, like other scanning methods. However, it can’t detect tumors on the periphery of the lung.

The future may offer even more sophisticated methods to detect lung cancer.
“What is really going to be useful is proteomics,” Bull says.“ We will be able to detect an abnormal molecule from a sample. It will detect a protein product from a tumor in its earliest stage.”

Treating lung cancer

If caught soon enough, surgeons can remove tumors caused by slow-growing forms of lung cancer, like non-small cell lung cancer. Since small cell lung cancer spreads so quickly, surgery is rarely recommended as treatment. A systemic approach, using chemotherapy and radiation, offers the best hope of survival for patients.

Advances in chemotherapy are also improving outcomes for patients with both types of lung cancer. New treatments target chemotherapy toxins directly to the cancerous cells. Research is also being conducted on the effects of anti-angiogenesis drugs on lung cancer. These drugs block the blood supply to tumors, starving them to death. Because women are more likely to develop lung cancer, doctors and scientists are also investigating the role hormones play in the development of lung cancer.

Bull is optimistic about future treatments for lung cancer.

“Survival rates are improving because we have a lot more in the way of therapy now,” Bull says. “Chemotherapy is definitely prolonging life and giving more people a longer disease-free interval.”