Deaths from cancer have been on a steady decline, dropping by nearly 25 percent since 1991, the year cancer mortality peaked in the United States, experts from the American Cancer Society reported Thursday.

A continuing decline in cigarette smoking, early detection and advances in cancer treatment combined to fuel a 23 percent decrease in cancer mortality, according to the society’s biostatisticians.

The drop translates into 1.7 million fewer people nationwide having died of all forms of cancer, based on data that tracks mortality from the peak year through 2012, the most recent for complete figures.

“It’s pretty amazing,” said Dr. Shahriyour Andaz, director of thoracic oncology at South Nassau Communities Hospital in Oceanside. He commended widespread public health efforts over multiple decades, which have helped lower rates of cigarette smoking.

“Smoking not only causes lung cancer,” Andaz said Thursday, “it also causes bladder, pancreas, kidney, esophagus and throat cancers. So all of these cancers are caused by smoking and when smoking rates go down so does the incidence of these other cancers.”

In New York, the report estimates 110,200 new cases of cancer in 2016, an increase of nearly 3,000 additional cancers compared with 2015. The report also predicts nearly 35,000 deaths statewide, a slight jump over the 34,600 deaths the society estimated for 2015. Neither the rise in incidence nor the predicted uptick in deaths are seen as statistically significant, the society’s experts say.

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While multiple factors play into survival, the new report underscored the importance of improvements in cancer therapeutics. The report did not address soaring costs, but noted more people are alive today because of treatment advancements.

On that front, Northwell Health announced Thursday a clinical trial that has grown out of its groundbreaking collaboration with Cold Spring Harbor Laboratory. The “bench-to-bedside” treatment alliance was forged between the two institutions last spring.

Later this month, the first clinical trial of the alliance is scheduled to start for women with HER2-positive breast cancer, an aggressive form of the disease. HER2-positive malignancies affect 1 in 5 women with breast cancer.

The American Cancer Society, meanwhile, noted in its new report that overall cancer incidence has remained stable in women over the last few years but has declined by 3.1 percent for men between 2009 and 2012. Experts estimated that at least half of the drop in men resulted from recent decreases in prostate cancer diagnoses and declining use of PSA testing.

Controversy has plagued PSA testing for years because of its tendency to produce false positive results.

Andaz, nevertheless, worries that screenings for lung cancer — spiral CT scans — are not being used enough and predicts that overall cancer survival gains could undergo a reversal unless more smokers — and former smokers — avail themselves of the technology.

“A lot of people don’t get screened because they think what they don’t know won’t hurt them,” Andaz said.

He is joining with Long Island advocate Geri Barish, president of Hewlett-based “1 in 9 Long Island Breast Cancer Action Coalition” to visit state lawmakers in the coming months. They hope to spur legislation that promotes lung-cancer screening. Barish, a three-time breast cancer survivor, is throwing her support behind lung cancer screening, Andaz said, to help avert a possible crisis.

Andaz, director of clinical research at South Nassau Communities Hospital, predicts a jump in advanced lung cancers on Long Island and elsewhere in the greater metropolitan area by 2018 unless screening increases.

For colorectal cancer, there is no pending crisis, said Dr. Jules Garbus, a colorectal surgeon at Winthrop-University Hospital. Indeed, he commends patients for heeding the screening message.

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“These cancers are being caught earlier and at a much more treatable and curable stage,” said Garbus, noting that suspicious growths can be removed during a colonoscopy. “Even when patients need surgical correction, we can cure them without the need for additional chemotherapy and radiation.”