癌症治疗或将获得疫苗

The next big development in cancer treatment could be a vaccine.

After years of limited success of vaccines to treat cancer, scientists say research has made many advancements. Many doctors predict more vaccines will be out in five years.

They are not traditional vaccines that prevent disease. Instead, they are shots to shrink tumors and stop the cancer from coming back. Targets for these experimental treatments include breast and lung cancer. There were also gains reported this year for the deadly skin cancer melanoma and for pancreatic cancer.

Dr. James Gulley helps lead a center at the U.S. National Cancer Institute that develops immune treatments, including cancer treatment vaccines. "We're getting something to work. Now we need to get it to work better," he said.

More than ever, scientists understand how cancer hides from the body's immune system. Cancer vaccines, like other immune system treatments, strengthen the immune system to find and kill cancer cells. Some new cancer vaccines use mRNA, which was developed for cancer but was first used for COVID-19 vaccines.

For a vaccine to work, it needs to teach the immune system's T cells to recognize cancer as dangerous, said Dr. Nora Disis. She is with University of Washington Medicine's Cancer Vaccine Institute in Seattle. Once trained, T cells can travel anywhere in the body to hunt down danger, she said.

Patient volunteers are very important to the research.

Fifty-year-old Kathleen Jade learned she had breast cancer in late February. She waited on a hospital bed for her third dose of an experimental vaccine. She is getting the vaccine to see if it will shrink her tumor before surgery.

"Even if that chance is a little bit, I felt like it's worth it," Jade said.

Progress on treatment vaccines has been difficult. The first such vaccine, Provenge, was approved in the U.S. in 2010 to treat prostate cancer. It requires processing a patient's own immune cells in a lab and returning them through the veins. There are also treatment vaccines for early bladder cancer and advanced melanoma.

Early cancer vaccine research had difficulties. The cancer would outfight patients' weak immune systems, said Olja Finn. She is a vaccine researcher at the University of Pittsburgh School of Medicine.

"All of these trials that failed allowed us to learn so much," Finn said.

Finn's research is now centered on patients with whose cancers were caught early. That is because the experimental vaccines did not help with more advanced patients. Finn's group is planning a vaccine study in women with a low-risk form of breast cancer.

More vaccines that prevent cancer may be coming. Decades-old hepatitis B vaccines prevent liver cancer. HPV vaccines, introduced in 2006, prevent cervical cancer.

People with the condition Lynch syndrome have a 60 percent to 80 percent lifetime risk of developing cancer. Getting them to take part in cancer vaccine trials has been easy, said Dr. Eduardo Vilar-Sanchez of MD Anderson Cancer Center in Houston, Texas. He is leading two government-supported studies on vaccines for Lynch-related cancers.

Drug producers Moderna and Merck are developing a personalized mRNA vaccine for patients with melanoma. The vaccines are designed for each patient, based on the many differences in their cancer tissue. A personalized vaccine can train the immune system to hunt for the cancer's mutation and kill those cells.

The vaccines under development at the University of Washington are designed to work for many patients. Tests are ongoing in early and advanced breast cancer, lung cancer and ovarian cancer. Some results may come as soon as next year.

Jamie Crase was one of the first people to receive the ovarian cancer vaccine. She got the vaccine during a safety study 11 years ago. Crase was diagnosed with advanced ovarian cancer at the age of 34. She thought she would die young. Now she is 50, with no sign of cancer.

She does not know for sure if the vaccine helped. But, she said, "I'm still here."

I'm Ashley Thompson.

Dan Novak adapted this story for VOA Learning English based on reporting by The Associated Press.

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advance — n. beyond the basic level

dose — n. the amount of a medicine, drug, or vitamin that is taken at one time

tissue — n. a piece of soft and very thin paper that is used especially for cleaning

mutation — n. a change in the genes of a plant or animal that causes physical characteristics that are different from what is normal