Factors That Modify Risks of Radiation-Induced Cancer Page: 7 of 19
This article is part of the collection entitled: Office of Scientific & Technical Information Technical Reports and was provided to UNT Digital Library by the UNT Libraries Government Documents Department.
Extracted Text
The following text was automatically extracted from the image on this page using optical character recognition software:
even when the characteristics of the cancer population and the radiation
exposures are well known. Furthermore, each element of the methods or
procedures for calculation has its own uncertainties that modify risk, some
of which are interdependent. For example, among many are the sites and cell
types of cancer, precise radiation doses and dose rates, minimum latent
periods, radiation risk coefficients, time to tumor recognition, choice of
dose-response function, choice of time-response function, and influence of
individual or collective host factors and competing etiologic influences.
Complex models that can be constructed to integrate most of these modifying
factors into an overall assessment or quantitative estimation of risk must
necessarily influence the accuracy that can be ascribed to any value. This
further underscores the influence of the factors that modify risk, the
technical difficulties of the process, and the uncertainties of the numerical
values derived.
BIOLOGIC FACTORS
Among the most important biological characteristics that modify risk are the
tissue sites and cell types, the baseline cancer incidence, minimum latent
period, time to tumor recognition, and the influence of individual host and
competing etiologic influences.
TISSUE SITES AND CELL TYPES
Although ionizing radiation has been shown to produce a very wide array of
human cancers, for certain cell types, e.g., chronic lymphocytic leukemia,
radiation seems not to be detectably carcinogenic. For many tissue sites and
cell types, e.g., prostate cancer, the evidence is inadequate to establish or
deny carcinogenicity, and for some, e.g., multiple myeloma, the evidence is
inconclusive. Any published lists of human cancers considered to be
radiogenic (10, 15, 22) are invariably based on judgment as to the
sufficiency of the human data available and the cogency of the evidence
involving radiation as a cause. Nevertheless, even if the evidence is
suggestive of radiation carcinogenesis in different tissues, reliable
estimates of cancer risk coefficients are still necessary for each cell type
observed. At the present time, there are limited data only on the leukemias
and certain of their cell types; for solid cancers, the data are lacking. It
is nevertheless possible that as more data become available, differential
risk coefficients for certain cell types among solid tumors, as in the case
of leukemias, can be established.
CANCER INCIDENCE
When dealing with a defined population, there is a tendency to restrict risk
calculations to established national boundaries. Reliable estimates of
cancer incidence in a given population at a given time are difficult to find.
In the United States, for example, one national cancer registry, the SEER
Report of the National Cancer Institute (26), is perhaps considered most
reliable, but it only records age- and sex-specific cancer incidence rates
for the United States as average for an nine-year period, from 1973 to 1981,
and only for ten regions, representing about ten percent of the United States
population. The data are not homogenous; geographic and ethnic variations
6
Upcoming Pages
Here’s what’s next.
Search Inside
This article can be searched. Note: Results may vary based on the legibility of text within the document.
Tools / Downloads
Get a copy of this page or view the extracted text.
Citing and Sharing
Basic information for referencing this web page. We also provide extended guidance on usage rights, references, copying or embedding.
Reference the current page of this Article.
Fabrikant, J. I. Factors That Modify Risks of Radiation-Induced Cancer, article, November 1988; California. (https://digital.library.unt.edu/ark:/67531/metadc1204484/m1/7/: accessed April 25, 2024), University of North Texas Libraries, UNT Digital Library, https://digital.library.unt.edu; crediting UNT Libraries Government Documents Department.