Two years after she was diagnosed with stage 4 lung cancer, Wanda Poche has a hard time believing she ever had the disease.

"I always felt like from the date I was diagnosed that I didn't have cancer," she said.

The 65-year-old woman is cancer-free after receiving a newly developed treatment that uses the body's immune system to fight the disease. 

Immunotherapy, doctors say, is an innovative advancement that could change the way certain cancers are viewed.

"Everybody's excited about it," said Dr. Vince Cataldo, an oncologist at Mary Bird Perkins — Our Lady of the Cancer Center in Baton Rouge. "We're definitely on the forefront."

Chemotherapy attacks a cancer cell's DNA to stop the cell from dividing, thereby stopping the cancer's growth. Traditional chemotherapy "tears the immune system apart," Cataldo said. 

"It suppresses the immune system, and people's biggest side effects from chemotherapy are the risk of infection because there is no immune system," he said.

Immunotherapy tries to "make the immune system smarter," he said.

Normally, the body's immune system remains inactive until it needs to fight a threat. But our bodies put the brakes on the immune system to slow it down. An unchecked immune response can eventually kill you. 

The new immunotherapy cancer drugs remove those brakes, Cataldo said. 

"It has truly changed the way we fight multiple diseases," Cataldo said. 

Some prominent drugs, like the one Poche received, target certain cancer cells to make them prone to damage from the immune system. 

Cataldo explained that the cancer cells have a receptor similar to an antenna. The immunotherapy drugs block that antenna and allow the immune system to attack the cells. 

Poche's battle started in October of 2014 with what she thought was a nagging sinus infection. Her doctor took a chest X-ray and found lung cancer. Because she had quit smoking decades before, Poche was surprised.

"I never expected that," she said. "All through this, I never had shortness of breath. I could always climb stairs. I've always been pretty healthy."

But her cancer had spread to her adrenal gland and lymph nodes. The ear, nose and throat doctor had saved her life, she said.

After months of different chemotherapy treatments, Poche was making no progress against the tumors. Cataldo decided she would be a candidate for a trial of a drug marketed as OPDIVO.

Poche had no side effects from the drug, which Cataldo said is common. 

"It doesn't beat up the immune system," he said. "We don't normally see hair loss. We don't typically see vomiting."

After 15 months of IV infusions, there were no signs of Poche's tumors in an August scan. Last month she had a full-body scan, and the cancer had not returned.

"It was still showing clear," she said. "God is great."  

Poche will take the treatments every two weeks for the foreseeable future to stop the cancer from returning. But that's a small price to pay, she said.

While immunotherapy works well for lung cancer, it doesn't treat all cancers. This class of drug has been approved to treat kidney cancer, melanoma and Hodgkin lymphoma in addition to lung cancer, diseases that "have nothing in common," Cataldo said. 

But the therapy doesn't work for everyone. Patients who have autoimmune disorders like rheumatoid arthritis or lupus may experience harsh side effects. 

Doctors are hopeful that more cancers can be treated with this type of drug.

"Cancer centers are looking for new indications, and they're doing cutting-edge clinical trials to see what the next one is going to be," Cataldo said.

Follow Kyle Peveto on Twitter, @kylepeveto.