Fifteen police officers died in 2018 from cancers related to the terrorist attack on the World Trade Center on September 11, 2001, according to a new report. The 9/11-related deaths were part of an overall uptick in fatalities among law enforcement officers this year.

Police officer deaths nationwide increased by 12 percent this year, climbing to 144 fatalities as of December 27, up from 129 in 2017, according to the National Law Enforcement Officers Memorial's annual fatalities report. Firearms were the leading cause of death in the line of duty, claiming the lives of 52 officers, a 13 percent increase from 2017, according to the report. The most recent addition to that list, Cpl. Ronil Singh of Newman, Calif., was shot and killed at a traffic stop Wednesday.

Another 50 officers were killed in traffic-related incidents in the line of duty.

The report also detailed the growing toll of cancer-causing toxins present during the search and recovery effort at Ground Zero after the 9/11 attacks. These illnesses were responsible for 15 police officer deaths in 2018, a four-fold increase from the year before, according to the report. Nearly 10,000 people have suffered from similarly caused cancers, according to data from the World Trade Center Health Program, an arm of the Centers for Disease Control and Prevention that provides health care for first responders and lower Manhattan residents impacted by the 9/11 attacks.

More than 580 people, including first responders, survivors and Manhattan residents, have died from 9/11-related cancers as of September 30 of this year, according to the CDC.

"[The 9/11 first responders] are a fraternity that's shrinking," said John Feal, an advocate for World Trade Center first responders. "9/11 hasn't ended, it's the longest day in the history of days."

Feal lost half his foot to an injury during a search and rescue mission at Ground Zero in the days following the attack. Now, he works as an advocate the WTC Health Program, encouraging those who volunteered at the time to receive screenings and care. The organization has over 90,000 members including survivors and first responders, according to its quarterly report.

The 9/11 Memorial and Museum will soon be opening a new section to honor the first responders and local residents who have passed away due to World Trade Center-related toxins and cancers, according to a museum official.