In an ongoing registry study, incidence rates of all cancers combined were 15% higher than expected (Standardized Incidence Ratio [SIR]: 1.15, 95% CI 1.06 to 1.25), Samara Solan, MD, of the Icahn School of Medicine at Mount Sinai Medical Center in New York, and colleagues reported in Environmental Health Perspectives.
Incidence rates were also higher for thyroid, prostate, hematopoietic/lymphoid, and soft-tissue cancers, they found.
Solan acknowledged in a statement that the "findings of this study, while significant, should be interpreted with caution given the short follow-up and long latency period for most cancers; the intensive medical surveillance of this cohort by Mount Sinai researchers and our partners; and the small numbers of cancers at specific sites.
"However," she added, "our findings strongly highlight the need for continued follow-up and medical surveillance of WTC responders."
Solan and her colleagues analyzed data from their ongoing WTC Health Program, which has enrolled 20,984 workers who were involved in rescue efforts on and after Sept. 11. Overall, 575 cancers were diagnosed in 552 patients.
They found increases in incidence rates for several types of cancers that were higher than expectations:
- All cancer sites combined SIR 1.15, 95% CI 1.06 to 1.25
- Thyroid cancer: SIR 2.39, 95% CI 1.70 to 3.27
- Prostate cancer: SIR 1.21, 95% CI 1.01 to 1.44
- Combined hematopoietic and lymphoid cancers: SIR 1.36, 95% CI 1.07 to 1.71
- Soft tissue cancers: SIR 2.26, 95% CI 1.13 to 4.05
- They also saw positive associations for non-Hodgkin lymphoma and kidney cancer, but those weren't significant.
When the study was restricted to the 302 cancers diagnosed 6 or more months after enrollment, the incidence rates for all cancers combined and for hematopoietic/lymphoid cancers became nonsignificant, falling to SIR 1.06 (95% CI 0.94 to 1.18) and to SIR 0.77 (95% CI 0.49 to 1.16), respectively.
But thyroid and prostate cancer diagnoses still remained greater than expected, they wrote.
Lung cancer incidence rates were significantly lower than expected in both the initial and restricted analyses (SIR 0.89 and SIR 0.62, respectively), but it's not clear why this may be.
The researchers cautioned that the observation about thyroid cancer may be an artifact due to increased medical surveillance, particularly because there was no evidence of Iodine-131 -- which has a strong causal link to thyroid cancer -- at Ground Zero.
Please read full and follow Kristina Fiore, Staff Writer, at MedPage Today: