A study released by the New York City Department of Health finds no clear link between most cancer and the dust, debris and fumes released on September 11th.
The study examined more than 55,000 people exposed in the aftermath of the attack.
It included rescue and recovery workers at the World Trade Center, on barges or at the Staten Island landfill, where debris was taken.
Overall, there was no increase in the cancer rate of those studied compared with the rate of the general population.
However, the study did find multiple myeloma, prostate cancer and thyroid cancer were significantly more prevalent in the rescue and recovery workers but not in the rest of the exposed population.
The study comes six months after the federal government added 50 types of cancer to the list of illnesses covered by the James Zadroga September 11th Health and Compensation Act.