In late 2010, Congress set up two programs for anyone exposed to the rubble, smoke and dust at ground zero: rescue and cleanup workers and others who worked or lived in the area. Cancer was initially excluded, but Congress ordered periodic reviews based on the latest scientific evidence.
One $1.55 billion program is for treatment for any illness determined to be related to ground zero. The second $2.78 billion fund is to compensate people who suffered economic losses or a diminished quality of life because of their illness. Both programs expire in 2016, but could be extended.
How many people might apply isn't clear. In the decade since the attacks, about 60,000 people have enrolled in the two health programs for those who lived or worked within the disaster zone of lower Manhattan. Many have signed up for medical monitoring, but around 16,000 have been getting treatment annually.
Every new illness added to the list means less money for the group as a whole, especially when dealing with major diseases like cancer, acknowledged Sheila Birnbaum, the special master handling applications to the compensation fund.
Registration for the compensation program only began in October. How the money will be divvied up, or whether it will be enough, isn't clear, Birnbaum said. People with the gravest health problems would get the largest amounts, with cancer payments likely among the most sizable.
Applicants could qualify for treatments and payments as long as they and their doctors make a plausible case that their disease was connected to the caustic dust.
But is Sept. 11 really to blame for every cancer case?
Overall, roughly 1 in 2 men and 1 in 3 women will get cancer over their lifetimes. And generally, the more you look for cancer, the more cases you find. People worried that they got sick from the World Trade Center attacks are likely going to doctors more than other people. So some slow-growing cancers that started before 9/11 but were found afterward could end up being blamed on the fallout.
Reggie Hilaire was a rookie police officer when the hijacked planes flew into the World Trade Center. He spent the initial weeks after the attacks patrolling Harlem, miles away from the disaster zone, then was sent to Staten Island, where he spent weeks at a city landfill sorting through rubble and looking for human remains.
At the landfill, he wore a Tyvek suit, boots, gloves and a respirator to protect him. Months later, he also worked as a guard near ground zero, wearing no protective gear but never working on the debris pile itself.
Hilaire didn't develop the hacking cough or other problems experienced by those who inhaled big doses of soot. But he worried about his health, periodically visiting doctor's offices and clinics.
In 2005, at age 34, a lump showed up in his neck. He was diagnosed with thyroid cancer and successfully treated. Months later, he got more bad news: Doctors noticed he was anemic and investigated, leading to diagnosis of a second cancer — multiple myeloma, a blood cancer normally seen in the elderly.
Since roughly half of people with the diagnosis never get sick from it, doctors monitor a patient's condition rather than put them through chemotherapy and other difficult treatments — which is the case with Hilaire, still on the force. His medical bills have been covered by insurance, and to date, he hasn't applied for compensation from the federal fund.
Doctors don't know what causes multiple myeloma, but say genetics plays a role and that it is more common in black men. Hilaire, who is black, is convinced that toxins at ground zero are to blame.
"I've had cancer twice since 9/11, and I'm 41 years old," he said. "It would be some coincidence."
The U.S. government traditionally has been cautious about labeling things as cancer-causing agents, choosing to wait for multiple studies to confirm and reconfirm such a conclusion.