Screenings, advances in cancer prevention and treatment and declines in tobacco use have combined to create good news: Cancer rates have dropped 22 percent in two decades, the American Cancer Society said.

Death rates from four major types of cancer - lung, breast, prostate and colon - drove the decrease, the society reported.

"It's wonderful news," said Dr. Richard Wender, chief cancer control officer for the society in Atlanta. "There's no mystery about how this happened. The biggest factor has been reduction in tobacco use - first in men and then in women."

While rates dropped largely because more people are putting out their cigarettes for good, cancer experts said advancements in screening are also helping save more lives.

Screenings for breast and colon cancer are key, said Cam Scott, senior director of government relations in Texas for the American Cancer Society Cancer Action Network.

"Basically, breast cancer is a curable form of cancer if it is caught early," Scott said. "If breast cancer is caught at an early stage there is a 98 percent survival rate."

The survival rate drops to 24 percent if caught later, Scott said.

The American Cancer Society's annual statistics report states that the 22 percent drop in cancer mortality helped avoid more that 1.5 million cancer deaths.

Lung cancer deaths among men rose during most of the 20th century, peaking in 1991. Since then, a steady decline in the cancer death rate is credited to fewer Americans smoking.

Wender said lung cancer deaths have "plummeted" in men and are dropping in women too. Such deaths declined 36 percent from1990 to 2011 among men and 11 percent from 2002 to 2011 among women.

"We could be doing much better if we reduced tobacco far more substantially than we already have," Wender said.

Jonni Alvarez, 42, a nurse manager at Texas Health Harris Methodist Hospital Fort Worth, Texas, quit smoking after 26 years when she learned her friend has lung cancer.

She had heard about the dangers of smoking all her life but continued. Alvarez had tried quitting but her friend's diagnosis was an eye-opener.

"It is very, very scary to think about it causing cancer," Alvarez said.

Death rates for breast cancer among women are down more than a third from peak rates, while prostate and colorectal cancer death rates are also decreasing.

Efforts to reduce barriers to testing include substantially eliminating co-payments for screenings, Scott said.

Scott said there are provisions in the Affordable Care Act to help people get access to mammograms and colon cancer screenings.

"Most people need to know they can get these screenings at no cost to them and it could potentially save their lives," Scott said.

Still, many people don't get screened because they feel healthy or don't have a family history of cancer. Wender said many people tell themselves: "I feel fine. Why would I do something if I feel fine?"

Rhonda Morton Eltiste wasn't showing any cancer symptoms cancer in 2012 when a screening detected a "very aggressive cancer" in her left breast.

A routine mammogram at age 43 led to further screening and eventually a biopsy. Those were followed by confirmation from doctors: "It is cancer."

On April 18, 2012, Morton had a double mastectomy. By Sept. 13, 2012, she had completed eight rounds of dose-dense chemotherapy.

The 45-year-old accountant from Willow Park, Texas, urges people to get screened.

"The best compliment I get is when someone tells me, 'I had a mammogram because of you,'" she said. "If I can help anyone else through this little journey, then maybe it helps this make sense."

Morton calls herself a poster child for mammograms. She said that because she got screened she is able "to live another day."

Morton is looking forward to her 46th birthday on Feb. 13. This year, her birthday celebration includes a trip to Disney World.

"I get to have another birthday," Morton said.