Donna Summer Lung Cancer: Disco Legend's Condition, Explained

Disco legend Donna Summer has passed away at age 63, from what news reports say was a battle with lung cancer.

TMZ reported that Summer was private about her illness, and that there may have been a connection between debris from 9/11 and her lung cancer:

TMZ has learned ... Donna died from lung cancer. Several sources are telling us Donna believed she contracted it by inhaling toxic particles after the 9/11 attack in New York City.

However, there are very few details about Summer's cancer, or if there were any complications that were involved with her death.

The family of the "She Works Hard for the Money" singer issued a statement, AFP reported, which said: "While we grieve her passing, we are at peace celebrating her extraordinary life and her continued legacy. Words truly can't express how much we appreciate your prayers and love for our family at this sensitive time."

Lung cancer is the No. 1 cause of cancer death for both men and women in the United States, according to the Mayo Clinic. The National Cancer Institute reports that there have been 226,160 new cases of lung cancer so far this year, and 160,340 deaths from the disease.

The cancer occurs when tumors form in lung tissue, most commonly in the cells that line the air passages, according to the National Cancer Institute. There are two main types: small cell lung cancer and non-small cell lung cancer. Small cell lung cancer tends to be more aggressive than non-small cell lung cancer, according to Cedars Sinai.

Risk for the disease is highest among smokers, according to the Mayo Clinic, though lung cancer can also occur in never-smokers, too.

In fact, there is some research to suggest that lung cancer in smokers may actually be a separate disease from lung cancer in never-smokers; a study presented at the American Association for Cancer Research conference last year suggested that there are DNA differences in the tumors from lung cancer in smokers and lung cancer in nonsmokers, LiveScience reported.

Researchers said at the World Conference on Lung Cancer that it can also be caused by exposure to secondhand smoke, radon gas and other carcinogens, as well as air pollution, the American Cancer Society reported. Family history may also play a role.

Older people are more likely to develop lung cancer than young people, with 80 percent of lung cancers occurring in those ages 60 and older, according to MacMillan Cancer Support.

That's supported by a chart on the Centers for Disease Control and Prevention website that reveals an increase in lung cancer prevalence as we age. The chart on its site calculates lung cancer risk based on current age. For example, 2.29 percent of men -- around two or three for every 100 men -- who are currently age 60 will go on to develop lung cancer in the next 10 years. However, that increases to 7.6 percent of men -- around seven or eight for every 100 men -- when looking ahead to the next 30 years.

Recently, "Big Love" actor Luke Askew and former Penn State football coach Joe Paterno also died of lung cancer.