Researchers have reported the largest-ever single-year drop in cancer death rates in the United States.

The rate of deaths from cancer fell 2.2 percent from 2016 to 2017. That is the largest drop since record-keeping began in 1930.

The information comes from a new report by the American Cancer Society. The group announced the report's findings Wednesday.

The Cancer Society says that overall death rates from cancer have fallen about 1.5 percent each year since 1991. Better treatments for lung cancer are part of the reason for the falling numbers, said Rebecca Siegel. She was the lead writer of the report.

"Lung cancer has been the most common cause of cancer death in the United States, and now...we have better therapies for our patients and ... patients are living longer and better than ever before."

If deaths from lung cancer were not counted, the 2017 rate drop would only be 1.4 percent, Siegel added.

In addition to better treatments, fewer people are getting lung cancer because fewer people are smoking.

Improved treatments for lung cancer include the areas of surgery, scanning, and use of radiation.

There are also better drugs. Genetic testing helps doctors choose the right drugs for the kind of cancer in a patient.

Doctor Jyoti Patel is a lung cancer expert with Northwestern University in Illinois.

She said new drugs that get the patient's own immune system to fight the cancer could help make the death rate fall even more.

American Cancer Society researchers also found a large decrease in the death rate from melanoma, a kind of skin cancer. It has fallen by 7 percent a year recently. The decrease is largely because of new drugs that became available about nine years ago.

There are differences in cancer rates among racial and ethnic groups in the United States. African Americans have for many years had higher rates of cancer than white Americans. However, that gap is shrinking. Hispanic Americans have generally had the lowest cancer rates.

I'm Jill Robbins.

Mike Stobbe reported on this story for the Associated Press. Jill Robbins adapted it for Learning English. Ashley Thompson was the editor.

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surgery – n. medical treatment in which a doctor cuts into someone's body in order to repair or remove damaged or diseased parts

scan – v. to look at the inside of (something) by using a special machine

immune system – n. the system that protects your body from diseases and infections

hepatitis – n. a serious disease of the liver that causes fever and makes your skin and eyes yellow